EXHIBIT 3.1.2

                                     FORM OF

            FOURTH AMENDED AND RESTATED CERTIFICATE OF INCORPORATION

                                       OF

                                  NANOSYS, INC.

      Nanosys, Inc., a corporation organized and existing under the laws of the
State of Delaware, hereby certifies as follows:

      A.    The name of the corporation is Nanosys, Inc. The corporation was
originally incorporated under the same name and the date of filing the original
Certificate of Incorporation of this corporation with the Secretary of State of
the State of Delaware is July 12, 2001.

      B.    Pursuant to sections 242 and 245 of the General Corporation Law of
the State of Delaware, this Amended and Restated Certificate of Incorporation
amends and restates the provisions of the Third Certificate of Incorporation of
this corporation filed on April 10, 2003 and supersedes the Certificates of
Amendment filed on June 4, 2003 and March 18, 2004.

      C.    The Certificate of Incorporation, as amended to date, of this
corporation is hereby amended and restated to read as follows:

      ONE. The name of the corporation is Nanosys, Inc. (the "Corporation" or
the "Company").

      TWO. The address of the registered office of the Corporation in the State
of Delaware is the Corporation Trust Company, 1209 Orange Street, in the City of
Wilmington, County of New Castle, Delaware 19801 and the name of the registered
agent at that address is The Corporation Trust Company.

      THREE. The purpose of the Corporation is to engage in any lawful act or
activity for which a corporation may be organized under the General Corporation
Law of the State of Delaware.

      FOUR. The filing of this Amended and Restated Certificate of Incorporation
shall result in the following, effective on the date this Fourth Amended and
Restated Certificate of Incorporation is filed with the Delaware Secretary of
State (the "Effective Date"):



                  a. By the filing of this Fourth Amended and Restated
Certificate of Incorporation and no further action on the part of the
Corporation or holders of the Common Stock or Preferred Stock of the
Corporation, each: (i) three (3) shares of Common Stock of this Corporation
outstanding as of immediately prior to the Effective Date shall be combined and
converted into one (1) share of Common Stock; (ii) three (3) shares of Series A
Preferred Stock (the "Series A Preferred") outstanding as of immediately prior
to the Effective Date shall be combined and converted into one (1) share of
Series A Preferred; (iii) three (3) shares of Series B Preferred Stock (the
"Series B Preferred") outstanding as of immediately prior to the Effective Date
shall be combined and converted into one (1) share of Series B Preferred; and
(iv) three (3) shares of Series C Preferred Stock (the "Series C Preferred")
outstanding as of immediately prior to the Effective Date shall be combined and
converted into one (1) share of Series C Preferred (the "Reverse Split"). Such
Reverse Split shall be effected on a certificate-by-certificate basis and the
Corporation shall pay cash in lieu of any fractional shares resulting from such
combination.

                  b. This Corporation is authorized to issue two classes of
stock to be designated, respectively, "Common Stock" and "Preferred Stock." The
total number of shares that the Corporation is authorized to issue is
66,916,667, 53,500,000 of which are designated Common Stock and 13,416,667
shares of which are designated Preferred Stock. Of the Preferred Stock,
1,833,333 shares are designated Series A Preferred, 4,333,334 shares are
designated Series B Preferred and 7,250,000 shares are designated Series C
Preferred. The Preferred Stock shall have a par value of one tenth of one cent
($0.001) per share and the Common Stock shall have a par value of one tenth of
one cent ($0.001) per share.

                  c. All actions contemplated by these Paragraphs (a) through
(c) of this preamble to Article FOUR shall be deemed to occur simultaneously.
All numbers of shares, and all amounts stated on a per share basis contained in
this Fourth Amended and Restated Certificate of Incorporation, including,
without limitation, the numbers set forth in this preamble to Article FOUR, are
stated after giving effect to the Reverse Split and no further adjustment shall
be made as a consequence thereof.

      The rights, preferences, privileges and restrictions granted to or imposed
upon the Common Stock and the Preferred Stock are as follows:

      A. Dividends. The holders of the Preferred Stock shall be entitled to
receive dividends out of funds legally available therefor, at the annual rates
of $0.072, $0.288 and $0.447 per share of Series A Preferred, Series B Preferred
or Series C Preferred, respectively, held by them, as adjusted for stock splits,
stock dividends, recapitalizations, and similar events, prior and in preference
to the declaration or payment of any dividend or other distribution (payable
other than in Common Stock) with respect to the Common Stock, when, as and if
declared by the Board of Directors. Such dividends shall not be cumulative and
no right to such dividends shall accrue to holders of Preferred Stock unless
declared by the Board of Directors. No dividends or other distributions shall be
made with respect to the Common Stock, other than dividends payable solely in
Common Stock, unless (i) dividends shall have been paid or declared and set
apart for payment, on account of all shares of Preferred Stock then issued and
outstanding, at the aforesaid rates for such calendar year, and (ii) the
Corporation shall declare and pay at the same time to each holder of Preferred
Stock a dividend equal to the dividend that would have been payable to

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such holder if the shares of Preferred Stock held by such holder had been
converted into Common Stock on the record date for the determination of holders
of Common Stock entitled to receive such dividend.

      B. Liquidation Preference.

            1. Preferred Stock Preference. In the event of any liquidation,
dissolution or winding up of the Corporation, either voluntary or involuntary
(each a "Liquidation Event"), the holders of Series A Preferred, Series B
Preferred and Series C Preferred shall be entitled to receive on a pari passu
basis and prior and in preference to any distribution of any of the assets or
surplus funds of the Corporation to the holders of Common Stock by reason of
their ownership thereof, the amount of $0.90 (the "Original Series A Issue
Price"), $3.60 (the "Original Series B Issue Price") or $5.601 (the "Original
Series C Issue Price") per share (each as adjusted for Preferred Stock splits,
Preferred Stock dividends, recapitalizations, and similar events relating to the
Preferred Stock) for each share of Series A Preferred, Series B Preferred or
Series C Preferred then held and, in addition, an amount equal to all declared
but unpaid dividends on the Series A Preferred, Series B Preferred or Series C
Preferred, as applicable. If the assets and funds thus distributed among the
holders of the Series A Preferred, Series B Preferred and Series C Preferred are
insufficient to permit the payment to such holders of their full preferential
amounts, then the entire assets and funds of the Corporation legally available
for distribution shall be distributed among the holders of Series A Preferred,
Series B Preferred and Series C Preferred in proportion to the full preferential
amount each such holder is otherwise entitled to receive under this Section
B(1). No payment shall be made with respect to the Common Stock unless and until
full payment has been made to the holders of the Series A Preferred, Series B
Preferred and Series C Preferred of the amounts they are entitled to receive
under this Section B(1).

            2. Remaining Assets. After payment to the holders of the Preferred
Stock of the amounts set forth in Section B(1) above, the remaining assets and
funds of the Corporation legally available for distribution, if any, to
stockholders shall be distributed among the holders of Preferred Stock and
Common Stock pro rata and based on the number of shares of Common Stock held by
each (assuming conversion of all such Preferred Stock), provided that the
maximum distribution that a holder of Preferred Stock may receive pursuant to
Sections B(1) and (2) is 225% of the sum of (i) Original Series A Issue Price
multiplied by the number of shares of Series A Preferred then held by such
holder, (ii) Original Series B Issue Price multiplied by the number of shares of
Series B Preferred then held by such holder, and (iii) Original Series C Issue
Price multiplied by the number of shares of Series C Preferred then held by such
holder. All remaining assets and funds after the maximum distribution to the
holders of Series A Preferred, Series B Preferred and Series C Preferred shall
be distributed to the holders of Common Stock.

            3. Reorganization or Merger. A reorganization, merger or
consolidation of the Corporation with or into any other corporation or entity or
a sale, conveyance or encumbrance of all or substantially all of the assets of
the Corporation, in which transaction or series of related transactions the
Corporation's stockholders immediately prior to such transaction own immediately
after such transaction less than 50% of the equity securities of the surviving
corporation or its parent, shall be deemed to be a Liquidation Event within the
meaning of this Section B, unless the holders of two-thirds in voting power of
the then outstanding shares of

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Preferred Stock (voting on an as-converted basis) elect to the contrary; such
election to be made by giving written notice thereof to the Corporation at least
three days before the effective date of such event. If such notice is given with
respect to the Preferred Stock, the provisions of Section C.6(d) shall apply.
Unless such election is made with respect to the Preferred Stock, any amounts
received by the holders of such Preferred Stock as a result of such merger or
consolidation shall be deemed to be applied toward, and all consideration
received by the Corporation in such asset sale together with all other available
assets of the Corporation shall be distributed toward, the preferred liquidation
distributions of the holders of Preferred Stock.

            4. Non-Cash Consideration. If any assets of the Corporation
distributed to stockholders in connection with any Liquidation Event are other
than cash, then the value of such assets shall be their fair market value as
determined in good faith by the Board of Directors, except that any securities
to be distributed to stockholders in a Liquidation Event shall be valued as
follows:

                  a. The method of valuation of securities not subject to
investment letter or other similar restrictions on free marketability shall be
as follows:

                        (i)   if the securities are then traded on a national
securities exchange or the Nasdaq National Market (or a similar quotation
system), then the value shall be deemed to be the average of the closing prices
of the securities on such exchange or system over the 30-day period ending three
(3) days prior to the distribution; and

                        (ii)  if actively traded over-the-counter, then the
value shall be deemed to be the average of the closing bid prices over the
30-day period ending three (3) days prior to the distribution; and

                        (iii) if there is no active public market, then the
value shall be the fair market value thereof, as determined in good faith by the
Board of Directors of the Corporation.

                  b. The method of valuation of securities subject to investment
letter or other restrictions on free marketability shall be to make an
appropriate discount from the market value determined as above in subsections
(a)(i), (ii) or (iii) of this Section B.4 to reflect the approximate fair market
value thereof, as determined in good faith by the Board of Directors.

            5. Notice and Opportunity to Exercise Conversion Rights.
Notwithstanding anything to the contrary that may be inferred from the
provisions of this Section B, each holder of Preferred Stock shall be entitled
to receive notice from the Corporation of any proposed liquidation, dissolution
or winding-up of the Corporation at least ten (10) days prior to the date on
which any such liquidation, dissolution or winding-up of the Corporation is
scheduled to occur and, at any time prior to any such liquidation, dissolution
or winding-up of the Corporation, to convert any or all of such holder's shares
of Series A Preferred, Series B Preferred or Series C Preferred into shares of
Common Stock pursuant to Section C hereof.

      C. Conversion. The holders of Preferred Stock shall have conversion rights
as follows (the "Conversion Rights"):

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            1. Right to Convert. Each share of Preferred Stock shall be
convertible, at the option of and without the payment of any additional
consideration by the holder thereof, at any time into such number of fully paid
and nonassessable shares of Common Stock as is determined by dividing the
Issuance Price (as defined below) by the Conversion Price (as defined below) in
effect at the time of conversion. The Issuance Prices for the Series A
Preferred, Series B Preferred and Series C Preferred shall be $0.90, $3.60 and
$5.601, respectively. The Conversion Prices for the Series A Preferred, Series B
Preferred and Series C Preferred, shall initially be $0.90, $3.60 and $5.601,
respectively, subject to adjustment as provided below. The number of shares of
Common Stock into which a share of Series A Preferred, Series B Preferred or
Series C Preferred is convertible is hereinafter referred to as the "Conversion
Rate" of such series of Preferred Stock, as appropriate.

            2. Automatic Conversion. Each share of Preferred Stock shall
automatically be converted into shares of Common Stock at the then effective
Conversion Rate (i) immediately prior to the closing of a firm commitment
underwritten public offering pursuant to an effective registration statement on
Form S-1 under the Securities Act of 1933 (the "Act") covering the offer and
sale of Common Stock for the account of the Corporation to the public with gross
proceeds to the Corporation of more than $30,000,000; or (ii) upon the consent
of holders of at least Sixty-Six and Two-Thirds percent (66 2/3%) of the
Preferred Stock then outstanding voting on an as-converted basis.

            3. Mechanics of Conversion. Before any holder of Preferred Stock
shall be entitled to convert the same into full shares of Common Stock and to
receive certificates therefor, such holder shall surrender the certificate or
certificates therefor, duly endorsed, at the office of the Corporation or of any
transfer agent for the Series A Preferred, Series B Preferred or Series C
Preferred, and shall give written notice to the Corporation at such office that
such holder elects to convert the same; provided, however, that in the event of
an automatic conversion pursuant to Section C.2 above, the outstanding shares of
Preferred Stock shall be converted automatically without any further action by
the holders of such shares and whether or not the certificates representing such
shares are surrendered to the Corporation or its transfer agent, and provided
further that the Corporation shall not be obligated to issue certificates
evidencing the shares of Common Stock issuable upon such automatic conversion
unless the certificates evidencing such shares of Preferred Stock are either
delivered to the Corporation or its transfer agent as provided above, or the
holder notifies the Corporation or the Corporation's transfer agent that such
certificates have been lost, stolen or destroyed and executes an affidavit to
such effect, in a form reasonably satisfactory to the Corporation. The
Corporation shall, as soon as practicable after such delivery, or such affidavit
in the case of a lost certificate, issue and deliver at such office to such
holder of Series A Preferred, Series B Preferred or Series C Preferred, a
certificate or certificates for the number of shares of Common Stock to which
the holder shall be entitled and a check payable to the holder in the amount of
any cash amounts payable as the result of a conversion into fractional shares of
Common Stock. Such conversion shall be deemed to have been made immediately
prior to the close of business on the date of such surrender of the shares of
Series A Preferred, Series B Preferred or Series C Preferred to be converted, or
in the case of automatic conversion in connection with an underwritten public
offering, immediately prior to the closing of the offering, and the person or
persons entitled to receive the shares of Common Stock issuable upon such
conversion shall be treated for all purposes as the record holder or holders of
such shares of Common Stock on such date.

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            4. Adjustments to Conversion Price of Preferred Stock for Dilutive
Issues:

                  a. Special Definitions. For purposes of this Section C.4, the
following definitions shall apply:

                        (i)   "Options" shall mean rights, options or warrants
to subscribe for, purchase or otherwise acquire either Common Stock or
Convertible Securities.

                        (ii)  "Convertible Securities" shall mean any evidences
of indebtedness, shares of capital stock (other than the Common Stock) or other
securities convertible into or exchangeable for Common Stock.

                        (iii) "Additional Shares of Common Stock" shall mean all
shares of Common Stock issued (or, pursuant to Section C.4(b), deemed to be
issued) by the Corporation, other than:

                              (A) shares of the Corporation's Common Stock
issued upon conversion of the Preferred Stock;

                              (B) shares of the Corporation's capital stock
issued pursuant to bone fide, arms-length acquisitions, mergers, technology
licenses or purchases, corporate partnering agreements or other similar
transactions approved by the Board of Directors;

                              (C) shares of the Corporation's capital stock (or
related options) issued to employees, officers, directors, consultants, or other
persons performing services for the Corporation (including, but not by way of
limitation, distributors and sales representatives) (collectively, "Service
Providers"), or (at the request of a Service Provider) issued to third parties
on behalf of any such Service Provider, pursuant to any stock offering plan or
arrangement approved by the Board of Directors;

                              (D) shares of the Corporation's capital stock
issued to financial institutions in connection with the extension of credit to
the Corporation, or to lessors in connection with the lease of equipment or real
property, which issuances are approved by the Board of Directors;

                              (E) shares of the Corporation's Common Stock
issued in connection with any stock split, stock dividend, or combination
thereof by the Corporation;

                              (F) all shares of Common Stock issued or issuable
upon conversion of Convertible Securities issued and outstanding on the date
this document is filed with the Delaware Secretary of State; or

                              (G) shares issued in a public offering in which
all of the Preferred Stock will be converted.

                  b. Deemed Issue of Additional Shares of Common Stock.

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                        (i)   Options and Convertible Securities. In the event
the Corporation at any time or from time to time after the original issuance
date for the Series C Preferred shall issue any Options or Convertible
Securities or shall fix a record date for the determination of holders of any
class of securities entitled to receive any such Options or Convertible
Securities, then the maximum number of shares (as set forth in the instrument
relating thereto assuming the satisfaction of any conditions to exercisability,
including, without limitation, the passage of time and without regard to any
provisions contained therein for a subsequent adjustment of such number) of
Common Stock issuable upon the exercise of such Options or, in the case of
Convertible Securities and Options therefor, the conversion or exchange of such
Convertible Securities, shall be deemed to be Additional Shares of Common Stock
issued as of the time of such issue or, in case such a record date shall have
been fixed, as of the close of business on such record date, provided that
Additional Shares of Common Stock shall not be deemed to have been issued unless
the consideration per share (determined pursuant to Section C.4(d) hereof) of
such Additional Shares of Common Stock would be less than the Conversion Price
for the Series A Preferred, Series B Preferred or Series C Preferred, as
applicable, in effect on the date of and immediately prior to such issue, or
such record date, as the case may be, and, provided further, that in any such
case in which Additional Shares of Common Stock are deemed to be issued:

                              (A) no further adjustment in the Conversion Price
shall be made upon the subsequent issue of Convertible Securities or shares of
Common Stock upon the exercise of such Options or conversion or exchange of such
Convertible Securities;

                              (B) if such Options or Convertible Securities by
their terms provide, with the passage of time or otherwise, for any increase or
decrease in the consideration payable to the Corporation, or in the number of
shares of Common Stock issuable, upon the exercise, conversion or exchange
thereof, the Conversion Price computed upon the original issue thereof (or upon
the occurrence of a record date with respect thereto), and any subsequent
adjustments based thereon, shall, upon any such increase or decrease becoming
effective, be recomputed to reflect such increase or decrease insofar as it
affects such Options or the rights of conversion or exchange under such
Convertible Securities;

                              (C) upon the expiration of any such Options or any
rights of conversion or exchange under such Convertible Securities which shall
not have been exercised, the Conversion Price computed upon the original issue
thereof (or upon the occurrence of a record date with respect thereto), and any
subsequent adjustments based thereon, shall, upon such expiration, be recomputed
as if;

                              (i) in the case of Convertible Securities or
Options for Common Stock, the only Additional Shares of Common Stock issued were
the shares of Common Stock, if any, actually issued upon the exercise of such
Options or the conversion or exchange of such Convertible Securities and the
consideration received therefor was the consideration actually received by the
Corporation for the issue of all such Options, whether or not exercised, plus
the consideration actually received by the Corporation upon such exercise, or
for the issue of all such Convertible Securities which were actually converted
or exchanged, plus the additional consideration, if any, actually received by
the Corporation upon such conversion or exchange, and

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                              (ii) in the case of Options for Convertible
Securities, only the Convertible Securities, if any, actually issued upon the
exercise thereof were issued at the time of issue of such Options, and the
consideration received by the Corporation for the Additional Shares of Common
Stock deemed to have been then issued was the consideration actually received by
the Corporation for the issue of all such Options, whether or not exercised,
plus the consideration deemed to have been received by the Corporation upon the
issue of the Convertible Securities with respect to which such Options were
actually exercised;

                              (D) no readjustment pursuant to clause (B) or (C)
above shall have the effect of increasing the Conversion Price to an amount
which exceeds the lower of (i) the Conversion Price on the original adjustment
date, or (ii) the Conversion Price that would have resulted from any issuance of
Additional Shares of Common Stock between the original adjustment date and such
readjustment date; and

                              (E) in the case of any Options which expire by
their terms not more than 90 days after the date of issue thereof, no adjustment
of the Conversion Price shall be made until the expiration or exercise of all
such Options.

                  c. Adjustment of Conversion Price Upon Issuance of Additional
Shares of Common Stock. In the event this Corporation shall issue Additional
Shares of Common Stock (including Additional Shares of Common Stock deemed to be
issued pursuant to Section C.4(b)(i)) after the original issuance date for the
Series C Preferred without consideration or for consideration per share less
than the Conversion Price for the Series A Preferred, Series B Preferred or
Series C Preferred, as applicable, in effect on the date of and immediately
prior to such issue (a "Dilutive Issuance"), then and in such event, the
Conversion Price for the Series A Preferred, Series B Preferred or Series C
Preferred, as applicable, shall be reduced, concurrently with such issue, to a
price determined by multiplying such Series A Preferred Conversion Price, Series
B Preferred Conversion Price or Series C Preferred Conversion Price by a
fraction, as applicable, the numerator of which shall be the number of shares of
Common Stock outstanding immediately prior to such issue (including shares
issuable upon conversion of the outstanding Preferred Stock and shares issuable
upon exercise, conversion or exchange of Options, convertible securities or
warrants for Preferred Stock) plus the number of shares of Common Stock which
the aggregate consideration received by the Corporation for the total number of
Additional Shares of Common Stock so issued would purchase at such Series A
Preferred Conversion Price, Series B Preferred Conversion Price or Series C
Preferred Conversion Price, as applicable; and the denominator of which shall be
the number of shares of Common Stock outstanding immediately prior to such issue
(including shares issuable upon conversion of the outstanding Preferred Stock
and shares issuable upon exercise, conversion or exchange of Options,
convertible securities or warrants for Preferred Stock) plus the number of such
Additional Shares of Common Stock so issued.

                  d. Determination of Consideration. For purposes of this
Section C.4, the consideration received by the Corporation for the issue of any
Additional Shares of Common Stock shall be computed as follows:

                        (i) Cash and Property: Such consideration shall:

                                      -8-


                              (A) insofar as it consists of cash, be computed at
the aggregate amount of cash received by the Corporation.

                              (B) insofar as it consists of property other than
cash, be computed at the fair value thereof at the time of such issue, as
determined in good faith by the Board of Directors irrespective of any
accounting treatment; and

                              (C) in the event Additional Shares of Common Stock
are issued together with other shares or securities or other assets of the
Corporation for consideration which covers both, be the proportion of such
consideration so received, computed as provided in clauses (A) and (B) above, as
determined in good faith by the Board of Directors.

                        (ii) Options and Convertible Securities. The
consideration per share received by the Corporation for Additional Shares of
Common Stock deemed to have been issued pursuant to Section C.4(b), relating to
Options and Convertible Securities, shall be determined by dividing:

                              (A) the total amount, if any, received or
receivable by the Corporation as consideration for the issue of such Options or
Convertible Securities, plus the minimum aggregate amount of additional
consideration (as set forth in the instruments relating thereto, without regard
to any provision contained therein for a subsequent adjustment of such
consideration) payable to the Corporation upon the exercise of such Options or
the conversion or exchange of such Convertible Securities, or in the case of
Options for Convertible Securities, the exercise of such Options for Convertible
Securities and the conversion or exchange of such Convertible Securities by

                              (B) the maximum number of shares of Common Stock
(as set forth in the instruments relating thereto, without regard to any
provision contained therein for a subsequent adjustment of such number) issuable
upon the exercise of such Options or the conversion or exchange of such
Convertible Securities.

            5. Fractional Shares. In lieu of any fractional shares to which the
holder of Preferred Stock would otherwise be entitled, the Corporation shall pay
cash equal to such fraction multiplied by the fair market value of one share of
Series A Preferred, Series B Preferred or Series C Preferred, as applicable, as
determined by the Board of Directors of the Corporation. Whether or not
fractional shares are issuable upon such conversion shall be determined on the
basis of the total number of shares of Preferred Stock of each holder at the
time converting into Common Stock and the number of shares of Common Stock
issuable upon such aggregate conversion.

            6. Adjustment of Conversion Price; Cash Dividends; Merger
Consideration.

                  a. The Conversion Price of each share of Series A Preferred,
Series B Preferred and Series C Preferred shall be subject to adjustment from
time to time as follows: (i) if the number of shares of Common Stock outstanding
at any time after the date hereof is increased by a stock dividend payable in
shares of Common Stock or by a subdivision or split-up of shares of Common
Stock, then, on the date such payment is made or such change is effective, the
Conversion Prices of the Series A Preferred, Series B Preferred and Series C
Preferred shall

                                      -9-


be appropriately decreased so that the number of shares of Common Stock issuable
on conversion of any shares of Series A Preferred, Series B Preferred and Series
C Preferred shall be increased in proportion to such increase of outstanding
shares; or (ii) if the number of shares of Common Stock outstanding at any time
after the date hereof is decreased by a combination of the outstanding shares of
Common Stock, then, on the effective date of such combination, the Conversion
Prices of the Series A Preferred, Series B Preferred and Series C Preferred
shall be appropriately increased so that the number of shares of Common Stock
issuable on conversion of any shares of Series A Preferred, Series B Preferred
and Series C Preferred shall be decreased in proportion to such decrease in
outstanding shares.

                  b. In case the Corporation shall declare a cash dividend upon
its Common Stock payable otherwise than out of retained earnings or shall
distribute to holders of its Common Stock shares of its capital stock (other
than Common Stock), stock or other securities of other persons, evidences of
indebtedness issued by the Corporation or other persons, assets (excluding cash
dividends) or options or rights (excluding options to purchase and rights to
subscribe for Common Stock or other securities of the Corporation convertible
into or exchangeable for Common Stock), then, in each such case, the holders of
the Series A Preferred, Series B Preferred and Series C Preferred shall,
concurrent with the distribution to holders of Common Stock, receive a like
distribution based upon the number of shares of Common Stock into which such
Series A Preferred, Series B Preferred and Series C Preferred is then
convertible.

                  c. In the event that the Common Stock issuable upon the
conversion of the Series A Preferred, Series B Preferred and Series C Preferred
shall be changed into the same or a different number of shares of any class or
series of stock or other securities or property, whether by capital
reorganization, reclassification, recapitalization or otherwise (other than a
subdivision or combination of shares or stock dividend provided for above, or a
merger, consolidation, or sale of assets provided for below), then and in each
such event the holder of any shares of Preferred Stock shall have the right
thereafter to convert such shares into the kind and amount of shares of stock
and other securities and property receivable upon such reorganization,
reclassification, recapitalization or other change by the holder of a number of
shares of Common Stock equal to the number of shares of Common Stock into which
such shares of Preferred Stock might have been converted immediately prior to
such reorganization, reclassification, recapitalization or change, all subject
to further adjustment as provided herein.

                  d. In the event that the Corporation shall merge or
consolidate with or into another entity or sell all or substantially all of its
assets, and such consolidation, merger or sale is not treated as a liquidation
under Section B.3, each share of Series A Preferred, Series B Preferred and
Series C Preferred shall thereafter be convertible into the kind and amount of
shares of stock or other securities or property to which a holder of the number
of shares of Common Stock of the Corporation deliverable upon conversion of such
Series A Preferred, Series B Preferred or Series C Preferred would have been
entitled to receive upon such consolidation, merger or sale; and, in such case,
appropriate adjustment (as determined in good faith by the Board of Directors)
shall be made in the application of the provisions set forth in this Section C
with respect to the rights and interest thereafter of the holders of shares of
such Preferred Stock, to the end that the provisions set forth in this Section C
(including provisions with respect to changes in and other adjustments of the
Conversion Price) shall thereafter be applicable, as nearly as reasonably may
be, in relation to any shares of stock or other securities

                                      -10-


or property thereafter deliverable upon the conversion of such Preferred Stock.
The provisions of this Section C.6(d) shall similarly apply to successive
reorganizations, reclassification, consolidations, mergers, sales or other
dispositions.

                  e. All calculations under Section C.4 and this Section C.6
shall be made to the nearest one hundredth (1/100) of one cent or to the nearest
one hundredth (1/100) of a share, as the case may be.

            7. Minimal Adjustments. No adjustment in the Conversion Price for
the Series A Preferred, Series B Preferred or Series C Preferred need be made if
such adjustment would result in a change in the Conversion Price of less than
$0.001. Any adjustment of less than $0.001 which is not made shall be carried
forward and shall be made at the time of and together with any subsequent
adjustment which, on a cumulative basis, amounts to an adjustment of $0.001 or
more in the Conversion Price.

            8. No Impairment. The Corporation shall not, by amendment of its
Certificate of Incorporation or through any reorganization, recapitalization,
transfer of assets, consolidation, merger, dissolution, issue or sale of
securities or any other voluntary action, avoid or seek to avoid the observance
or performance of any of the terms to be observed or performed hereunder by the
Corporation, but will at all times in good faith assist in the carrying out of
all the provisions of this Section C and in the taking of all such action as may
be necessary or appropriate in order to protect the Conversion Rights of the
holders of Preferred Stock against impairment. This provision shall not restrict
the Corporation's right to amend its Certificate of Incorporation with the
requisite stockholder consent.

            9. Certificate as to Adjustments. Upon the occurrence of each
adjustment or readjustment of any Conversion Rate pursuant to Section C, the
Corporation at its expense shall promptly compute such adjustment or
readjustment in accordance with the terms hereof and prepare and furnish to each
holder of Series A Preferred, Series B Preferred or Series C Preferred, as
applicable, a certificate setting forth such adjustment or readjustment and
showing in detail the facts upon which such adjustment or readjustment is based.
The Corporation shall, upon written request at any time from any holder of
Preferred Stock, furnish or cause to be furnished to such holder a like
certificate setting forth (i) all such adjustments and readjustments, (ii) the
applicable Conversion Rates at the time in effect, and (iii) the number of
shares of Common Stock and the amount, if any, of other property which at the
time would be received upon the conversion of such holder's shares of Preferred
Stock.

            10. Notices of Record Date. In the event of any taking by the
Corporation of a record of the holders of any class of securities for the
purpose of determining the holders thereof who are entitled to receive any
dividend (other than a cash dividend) or other distribution, any right to
subscribe for, purchase or otherwise acquire any shares of stock of any class or
any other securities or property or to receive any other right, the Corporation
shall mail to each holder of Preferred Stock at least twenty (20) days prior to
such record date, a notice specifying the date on which any such record is to be
taken for the purpose of such dividend or distribution or right, and the amount
and character of such dividend, distribution or right.

                                      -11-


            11. Notices. Any notice required by the provisions of this Section
C.4 to be given to any holder of Preferred Stock shall be deemed given if
deposited in the United States mail, postage prepaid, and addressed to each
holder of record at such holder's address appearing on the Corporation's books.

            12. Common Stock Reserved. The Corporation shall reserve and keep
available, free from pre-emptive rights, out of its authorized but unissued
Common Stock, solely for the purpose of effecting the conversion of the
Preferred Stock, such number of shares of Common Stock as shall from time to
time be sufficient to effect conversion of the Preferred Stock. If at any time
the number of authorized but unissued shares of Common Stock shall not be
sufficient to effect the conversion of all the then outstanding shares of
Preferred Stock, the Corporation shall promptly take such corporate action as
may, in the opinion of its counsel, be necessary to increase its authorized but
unissued shares of Common Stock to such number of shares as shall be sufficient
for such purpose.

            13. Certain Taxes. The Corporation shall pay any issue or transfer
taxes payable in connection with the conversion of Preferred Stock, provided,
however, that the Corporation shall not be required to pay any tax which may be
payable in respect of any transfer to a name other than that of the holder of
the Preferred Stock.

            14. Closing of Books. The Corporation shall at no time close its
transfer books against the transfer of any Preferred Stock or of any shares of
Common Stock issued or issuable upon the conversion of any shares of Preferred
Stock in any manner which interferes with the otherwise permissible timely
conversion or transfer of such Preferred Stock or Common Stock.

            15. Validity of Shares. The Corporation agrees that it will from
time to time take all such actions as may be required to assure that all shares
of Common Stock which may be issued upon conversion of any Preferred Stock will,
upon issuance, be legally and validly issued, fully paid and nonassessable and
free from all taxes, liens and charges with respect to the issue thereof.

      D. Voting Rights.

            1. Generally. The holder of each share of Preferred Stock shall be
entitled to the number of votes equal to the number of shares of Common Stock
into which each share of such Preferred Stock could be converted on the record
date for the vote or written consent of stockholders and, except as otherwise
required by law, shall have voting rights and powers equal to the voting rights
and powers of the Common Stock. The holder of each share of Preferred Stock
shall be entitled to notice of any stockholders' meeting in accordance with the
bylaws of the Corporation and shall vote with holders of the Common Stock upon
all matters submitted to a vote of stockholders, except with respect to those
matters required pursuant to Section E or by law to be submitted to a class or
series vote. Fractional votes shall not, however, be permitted and any
fractional voting rights resulting from the above formula (after aggregating all
shares of Common Stock into which shares of Preferred Stock held by each holder
could be converted) shall be disregarded. The holder of each share of Common
Stock shall have the right to one vote, and shall be entitled to notice of any
stockholders' meeting in accordance with the bylaws

                                      -12-


of the Corporation, and shall be entitled to vote upon such matters and in such
manner as may be provided by law.

            2. Directors.

                  a. Number of Directors. Except as reduced by Section D.2(c),
there shall be eight (8) directors of the Corporation, provided that such number
of directors may be increased with the affirmative vote or written consent of
the holders of a majority of Common Stock and the holders of a majority of the
Preferred Stock (voting on an as-converted basis), each voting as a separate
class.

                  b. Election by Class. The directors shall be elected as
follows:

                        (i)   One director (the "Series B Director") shall be
elected by the holders of a majority of the outstanding shares of Series B
Preferred voting together as a single class;

                        (ii)  Two directors (the "Series A Directors") shall be
elected by the holders of a majority of the outstanding shares of Series A
Preferred voting together as a single class;

                        (iii) Two directors (the "Common Directors") shall be
elected by the holders of a majority of the outstanding shares of Common Stock
voting together as a single class;

                        (iv)  Any remaining directors (the "Joint Directors")
shall be elected by the holders of a majority of the outstanding Common Stock
and Preferred Stock voting together as a single class, on an
as-converted-to-Common Stock basis.

                  c. Removal of Directors, Reduction of Number of Directors

                  .     (i) If at any time there are fewer than 100,000 shares
(appropriately adjusted for stock splits, stock dividends, recapitalizations and
similar events) of Series B Preferred outstanding (i) the right of the holders
of the shares of Series B Preferred to elect the Series B Preferred Director
will terminate, (ii) a voting shift shall be effected and the term of office of
the Series B Director will automatically terminate, and (iii) the authorized
number of directors shall be reduced by one. In addition, the Series B Director
may be removed by vote or written consent of a majority of the shares of Series
B Preferred then outstanding, voting as a single class.

                        (ii)  If at any time there are fewer than 33,333 shares
(appropriately adjusted for stock splits, stock dividends, recapitalizations and
similar events) of Series A Preferred outstanding (i) the right of the holders
of the shares of Series A Preferred to elect Series A Preferred Directors will
terminate, (ii) a voting shift shall be effected and the term of office of the
Series A Directors will automatically terminate, and (iii) the authorized number
of directors shall be reduced by two. In addition, the Series A Directors may be
removed by vote or written consent of a majority of the shares of Series A
Preferred then outstanding, voting as a single class.

                                      -13-


                        (iii) The Common Directors may be removed by vote or
written consent of a majority of the shares of Common Stock then outstanding,
voting as a single class.

                        (iv)  The Joint Directors may be removed by vote or
written consent of a majority of the shares of Common Stock and Preferred Stock
then outstanding, voting together as a single class on an as-converted-to-Common
Stock basis.

                  d. Vacancies.

                        (i)   In the event of a vacancy on the Board of
Directors created by the resignation, death, or removal of a Series B Director,
such vacancy shall be filled: (i) by the Corporation's Board of Directors upon
receipt by the Board of Directors of, and in accordance with, written consents
specifying the new director to fill such vacancy and signed by the holders of a
majority of the shares of the Series B Preferred then outstanding, or (ii) by
vote or written consent of the holders of a majority of the Series B Preferred
then outstanding.


                        (ii)  In the event of a vacancy on the Board of
Directors created by the resignation, death, or removal of a Series A Director,
such vacancy shall be filled: (i) by the Corporation's Board of Directors upon
receipt by the Board of Directors of, and in accordance with, written consents
specifying the new director to fill such vacancy and signed by the holders of a
majority of the shares of the Series A Preferred then outstanding, or (ii) by
vote or written consent of the holders of a majority of the Series A Preferred
then outstanding.


                        (iii) In the event of a vacancy on the Board of
Directors created by the resignation, death, or removal of a Common Director,
such vacancy shall be filled: (i) by the Corporation's Board of Directors upon
receipt by the Board of Directors of, and in accordance with, a written consent
specifying the new director to fill such vacancy and signed by the holders of a
majority of the shares of Common Stock then outstanding, or (ii) by vote or
written consent of the holders of a majority of the Common Stock then
outstanding.

                        (iv)  In the event of a vacancy on the Board of
Directors created by the resignation, death, or removal of a Joint Director,
such vacancy shall be filled: (i) by the Corporation's Board of Directors upon
receipt by the Board of Directors of, and in accordance with, a written consent
specifying the new director to fill such vacancy and signed by the holders of a
majority of the shares of Common Stock and Preferred Stock then outstanding,
voting as a single class on an as-converted-to-Common Stock basis, or (ii) by
vote or written consent of the holders of a majority of the Common Stock and
Preferred Stock then outstanding, voting together as a single class on an
as-converted-to-Common Stock basis.

                  e. Committees of Board of Directors. No audit committee or
compensation committee of the Board of Directors may include any director who is
an officer, employee or consultant of the Corporation.

                  f. Right to Call Meetings. In addition to any rights which may
be available under the Corporation's Bylaws or otherwise under law, the holders
of not less than twenty percent (20%) in voting power of the outstanding
Preferred Stock shall be entitled to call meetings of the stockholders of the
Corporation. Within five (5) business days after written application by the
holders of not less than twenty percent (20%) in voting power

                                      -14-


of the outstanding Preferred Stock, the President or Secretary, or such other
officer of the Corporation as may be authorized in the Bylaws of the Corporation
to give notice of meetings of stockholders of the Corporation, shall notify each
stockholder of the Corporation entitled to such notice of the date, time, place
and purpose of such meeting. No meeting of stockholders called pursuant to this
Section D(2) shall take place more than ten (10) days after the date notice of
such meeting is given.

      E. Protective Provisions. In addition to any other rights provided by law,
so long as 100,000 shares of Preferred Stock shall be outstanding, this
Corporation shall not, without first obtaining the affirmative vote or written
consent of the holders of at least Sixty-Six and Two-Thirds percent (66 2/3%) of
the then outstanding shares of Preferred Stock voting together as a single
class:

            1. materially and adversely alter or change the express rights,
preferences, privileges or restrictions on the Preferred Stock;

            2. increase or decrease the aggregate number of authorized shares of
Preferred Stock;

            3. authorize or create any series or class of capital stock having
rights, preferences or privileges senior to, or pari passu with, the Series A
Preferred, Series B Preferred or Series C Preferred;

            4. authorize (i) a merger or consolidation after which the
stockholders of the Corporation shall own less than a majority of the
outstanding voting stock of the surviving corporation or (ii) a sale of all or
substantially all of the assets of the Corporation;

            5. authorize a liquidation or dissolution of the Corporation; and

            6. declare or pay any cash dividend or redeem or repurchase any
shares of capital stock of the Corporation (other than redemption or repurchase
from terminated employees or service providers pursuant to contractual rights of
repurchase or redemption).

      F. Status of Converted Stock. No shares of Preferred Stock acquired by the
Corporation by reason of redemption, purchase, conversion or otherwise shall be
reissued, and all such shares shall be cancelled, retired and eliminated from
the shares which the Corporation shall be authorized to issue.

      G. Residual Rights. All rights accruing to the outstanding shares of
capital stock not expressly provided for to the contrary herein shall be vested
in the Common Stock.

      FIVE. The Corporation is to have perpetual existence.

      SIX. In furtherance and not in limitation of the powers conferred by
statute, the Bylaws of the Corporation may be altered, amended or repealed by
the Board of Directors of the Corporation, with, and only with, the approval of
a majority of the directors then in office.

                                      -15-


      SEVEN. The election of directors need not be by written ballot unless the
Bylaws of the Corporation shall so provide.

      EIGHT. Meetings of stockholders may be held within or without the State of
Delaware, as the Bylaws may provide. The books of the Corporation may be kept
(subject to any provisions contained in the statutes) outside the State of
Delaware at such place or places as may be designated from time to time by the
Board of Directors or in the Bylaws of the Corporation.

      NINE. The Corporation shall indemnify each person who at any time is, or
shall have been, a director or officer of the Corporation and was or is a party
or is threatened to be made a party to any threatened, pending or completed
action, suit or proceeding, whether civil, criminal, administrative or
investigative, by reason of the fact that he is or was a director or officer of
the Corporation, or is or was serving at the request of the Corporation as a
director, officer, employee, or agent of another corporation, partnership, joint
venture, trust or other enterprise, against expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement incurred in connection
with any such action, suit or proceeding, to the maximum extent permitted by the
General Corporation Law of the State of Delaware, as the same exists or may
hereafter be amended. In furtherance of and not in limitation of the foregoing,
the Corporation shall advance expenses, including attorneys' fees, incurred by
an officer or director of the Corporation in defending any civil, criminal,
administrative or investigative action, suit or proceeding in advance of the
final disposition of such action, suit or proceeding upon receipt of an
undertaking by or on behalf of such director or officer to repay such advances
if it shall be ultimately determined that he is not entitled to be indemnified
by the Corporation. The foregoing right of indemnification shall in no way be
exclusive of any other rights of indemnification to which any such director or
officer may be entitled, under any Bylaw, agreement, vote of directors or
stockholders or otherwise. No amendment to or repeal of the provisions of this
Article NINE shall deprive a director or officer of the benefit hereof with
respect to any act or failure to act occurring prior to such amendment or
repeal.

      TEN. No director of the Corporation shall be personally liable to the
Corporation or to any of its stockholders for monetary damages arising out of
such director's breach of his fiduciary duty as a director of the Corporation,
except to the extent that the elimination or limitation of such liability is not
permitted by the General Corporation Law of the State of Delaware, as the same
exists or may hereafter be amended. No amendment to or repeal of the provisions
of this Article TEN shall deprive any director of the Corporation of the benefit
hereof with respect to any act or failure to act of such director occurring
prior to such amendment or repeal.

      ELEVEN.Advance notice of new business and stockholder nomination for the
election of directors shall be given in the manner and to the extent provided in
the Bylaws of the Corporation.

      TWELVE.The Corporation reserves the right to amend, alter, change or
repeal any provision contained in this Fourth Amended and Restated Certificate
of Incorporation, in the manner now or hereafter prescribed by statute, and all
rights conferred upon stockholders herein are granted subject to this
reservation.

                                      -16-


      A.    This Fourth Amended and Restated Certificate of Incorporation has
been duly approved by the Board of Directors of this Corporation.

      B.    This Fourth Amended and Restated Certificate of Incorporation has
been duly adopted in accordance with the provisions of Sections 228, 242 and 245
of the General Corporation Law of the State of Delaware.

                                      -17-


      IN WITNESS WHEREOF, Nanosys, Inc. has caused this Fourth Amended and
Restated Certificate of Incorporation to be signed by the Chief Executive
Officer on _______ __, 2004.

                                                   Nanosys, Inc.

                                                   By: _________________________
                                                       Calvin Y. H. Chow
                                                       Chief Executive Officer

ATTEST:

By:__________________________________
   Michael J. O'Donnell
   Secretary

  (Signature Page to Fourth Amended and Restated Certificate of Incorporation)