A summary of the flow of genetic information in protein synthesis is useful as an overview:` Identify the indi-cated parts of the illustration on the next page by filling in the blanks with the names of the appropriate struc-tures or functions. Choose from the following: DNA, mRNA, tRNA, polypeptide, rRNA subunits, intron, exon,mature mRNA transcript, new mRNA transcript, anticodon, amino acids, ribosome-mRNA complex. Com-•-=afplete the exercise by matchirig`and entering-t -a letter-of-thedescription in the parentheses following each label.W

(ia-i) [pp236-237]

A. Coding portion of mRNA that will translate intoproteins19 r i = ctf 3) [gp.236-237]

B. Carries a modified form of the genetic code from DNA(process)

in the nucleus to- the cytoplasmC. Transports amino acids to the ribosome and mRNA20. O [pp.236-237]

D. The building blocks of polypeptides21. ETAn (() [pp.236-237]

E. Noncoding portions of newly transcribed mRNA22.

M

[pp.236-237]

F. tRNA after delivering its amino acid to the ribosomemPLNA complex

- r°'f

"'i T ^-L- j

G. Join when translation is initiated23. -

_fl (C„) [pp.236-237]

H. Holds the genetic code for protein production1. Place where translation occurs

24. ["

() [pp.236-237]

J. DNA template creates new RNA transcriptK. A sequence of three bases that can pair with a specific25. {) [pp.236-237]

mRNA codon26. ~t

() [pp.236-2371

L. Snipping out of introns, only exons remaining27 Z)M I` i

O [pp 236-237]

M. May serve as a functional protein (enzyme) or astructural protein

28. - N

(IF) [FF.236-237]

18.

29. r

) [pp.236-237]

30.1 (

[pp.236-237]

Complete the Table

-b. Three types of RNA are transcribed from DNA in the nucleus (from genes that code only for RNA)_ Com-plete the following table, which summarizes information about these molecules.

RNA Molecule Abbreviation Descrip€ioiz/Functi m

[p.228] a. Ribosomal RNA -'t

[p.228] b. Messenger RNA

8 c. Transfer RNA

Short Answer

17. List three ways in which a molecule of RNA differs struc-tura]ly from a mo'ecule of DNA. [p.2?5j

18. Cite two similarities in DNA replication and transcription. [p ^2.̂ a

19. What are the three key ways in which transcription differs from DNA replication? [p.228]

sequence that signals "stop." [p.230]

B. RNA polymerase binds with the DNA promoter region to open up a local region of the DNAdouble helix. [p.229]

22,

C. An RNA polymerase enzyme locates the DNA bases of the promoter region of one DNAstrand by recognizing DNA-associated proteins near a promoter. [p.229]

23.

D. RNA is released from the DNA template as a free, single -stranded transcript. [p.229]

24.

E. RNA polymerase moves stepwise along exposed nucleotides of one DNA strand; as it moves,the DNA double helix keeps unwinding. [p.229]

Sequence

Arrange the steps of transcription in correct chronological sequence. Write the letter of the first step next to 20,the letter of the second step next to 21, and so on.

20.4

A. The RNA strand grows along exposed bases until RNA polyrnerase meets a DNA base

p.228] uracil

Fill-in-the-Blanks

The pattern of which base follows the next in a strand of DNA is referred to as the base (1)

tt

[p.225]. A region of DNA that calls for the assembly of specific amino acids into a polypeptide chain is a(n)

(2) L, C

[p.225]. The two steps from genes to proteins are called (3)

[p.225] and

(4)A-t [p225]. In (5)

[p.225], single-stranded molecules of RNA are assembled on DNA

templates in the nucleus. In (6) `(2

[p.2251, the RNA molecules are shipped from the nucleus into

the cytoplasm, where they are used as templates for assembling (7)

[p.225] chains. Following

translation, one or more chains become (8):,C [p.225] into the three-dimensional shape of protein

molecules. Proteins have (9).

p.225]- and (10)x'

[p.225] roles in cells, including control

of DNA. Garrod hypothesized that an enzyme that operated at the next step of a (1

pathway was (12)

[p.226] and could explain why

accumulating in excess amounts in the body flu- is a fected individuals. Experimenting with red bread

mold, Beadle and Tatum founder ach inherited (13)

[p.226] corresponded to a defective

(14)

A more precise hypothesis regarding the relationship of genes with proteins

emerged from Ingram's work with hemoglobin: the amino acids of polypeptide chains-the structural units

of proteins-are encoded in (15)

[p.227].

of a particular substance were

Boldfaced, Page-Referenced Terms

[p.230] codons

Completion

10. Given the following DNA sequence, deduce the compo ition of tiie .RNA transcript: [p.230]

TAC AAG ATA ACA TTA TTT CCT ACC GTC ATClL_?_ C

(mRNA transcript)

11. Deduce the composition of the tRNA anticodons that would pair with the specific mRcNA-codons;-frcniquestion 10, as these tRNAs deliver the amino acids (identified below) to the P and A binding sites of thesmall ribosomal subunit. [p.2301

(tRNA anticodons)

12. From the naRNA transcript in question 10, use Figure 14.11 of the text to deduce the composition of theamino acids of the polypeptide sequence. [p.2301

(amino acids)

Fill-in-the-Blanks

The order of (13) c tYuf

i r ;'' [p.230] in a protein is specified by a sequence of nucleotide bases.

The genetic code is read in units of (14)

3

[p.2301 nucleotides; each unit of three codes for

(15)

a

[p.230] amino acid(s). In the table that showed which triplet specified a particular amino

acid, the triplet code was incorporated in (16) 012

[p.230] molecules. Each of these triplets is referred

to as a(n) (17) C

[p.230]. (18) tYY1

[p.230] alone carries the instructions for assembling a

particular sequence of amino acids from the DNA to the ribosomes in the cytoplasm, where (19)

t 3

[p.231] of the polypeptide occurs. (20)

[pp.230-231] RNA acts as a shuttle molecule as each type

brings its particular (21))ptl^'>

'i

[pp.230-231] to the ribosome where it is to be incorporated

into the growing (22) '`; " \ ' l [p.231]. A(n) (23) C ^ [p.230] is a triplet on mRNA that forms

hydrogen bonds with a(n) (24)ai'1^} -C [p.2301, which is a triplet on tRNA. During the stage of

translation called (25) V('

p.232], a particular tRNA that can start transcription and an mRNA

transcript are both loaded onto a ribosome. In the (26)€0'

[p.232] stage of translation, a polypeptide

chain is assembled as the mRNA passes between two ribosomal subunits, like a thread being movedi

through the eye of a needle. During the last stage of translation, (27)

[p.232], a STOP codon in

the mRNA moves onto the platform, and no tRNA has a corresponding anticodon. Now proteins called

(28)(\x

[p.232] factors bind to the ribosome. They trigger (29) L t

[p .232] activity that

detaches the mRNA and the chain from the ribosome.

Labeling

1. The term se,niconservative replication refers to the fact that each new DNA molecule resulting from the repli-

cation process is "half old, half new." In the following illustration, complete the replication required in the

middle of the molecule by adding the required letters representing the missing nucleotide bases. Recall that

ATP energy and the appropriate enzymes are actually required in order to complete this process. [p.220]

T- r

--A

G- C

C1._ -CA- ---

-T

C-

C -G

c-c

G

old new

new old

True-Fr Ise

if a statement below is true, write T in the blank. LF false, & r - in why Gy changing one or more of the under-

lined words.-i^tl' F S fl ^4

2. The hydrogen bonding of adenine to g ,_t } is an example of complem m ::; ase nay

[p.22r] t`

'_.._____3. The replication of DNA is considered a con -'T•vative process because each new molecule is

really half new and half old. [pp.220-2 21;

4. Each parent strand remains ir_tact duri np replication, and a new companion strand is

assembled on each of those parent stran'is. f,)-2201

5. DNA hga govern the assembly of nuc!zotides on a parent strand. [p.221]

6. DNA polymerases, DNA ligases, and other enzymes also en ;age in DNA replication.

[p.221]

Bol aced, Page-Referenced Terms

[p.254]

ne therapy

l t`

_

[p256] _' restrictionxen

fl2L A

C

IUiA 'at-

Fill-in-the-Blanks

A bacterio age is a kind of (2)

[p.216] that can infect (3)

[p-2161 cells. Enzymes from

the (2) take over e

h of the host cell's metabolic processes tc make substances that are necessary to

radioisotope remained outside the bacterial cells; the (9)

217] became part of the (10),

[p.217] injected into the cterial cells. Through many expz ten

s, researchers accuumulatc,

strong evidence that (11)

[p.2171, not (12)

[p.217], serves as me, molecule of

inheritance in all livinz cells.

3.2. DNA STRUCTURE z:,p.21 2191

3.3. Focus on Bioethics: ROSALIND'S STORY [p 220]

Selected Words: E. Chargaff [p_2181, R. Franklin and M. Wilkins [p.218], DNA double helix [p.219], x-raycrys tall ography [p.220]

Boldfaced, Page-Referenced Terris

construct new (4)

.2161. Some of these substances are (5)

[p.217] that can be labeled

with a radioisotope of sulfur, S.

enetic material of the bacteriophage used in the experiments by

Hershey and Chase was labeled with the radl ' tope of phosphorus known as (6)

[p.2171.

W,%Then (7)

[p.2171 particles were allowed to

ct Escherichia coli cells, the (S)

[p.2171

[p.218] nucleotide

[p.218] adenine, A

[p.218] guanine, C1 p

[p.218] thymi.ne, T

[p.218] cytosine, C __ 14 Nm1

coon images

Short Answer

1. List the three parts of a nucleotide. [p.218]{`,

beling

Four nucleotides are illustrat-obase correctly as guanine, thy

e from text p.218.] In the blank, label each nitrogen-containinge, or adenine. In the parentheses following each blank, indicate

or a pyrimidine (py). (See next section for definitions.)

Labeling and Matching

Identify each indicated part of the following DNA illustration.Choose from ese answers: phosphate group, double-ring ni-tro2en base, sin,, -ring nitrogen base, nucleotide, and de-oxyribose. Complete e exercise by matching and entering theletter of the proper stru re description in the parentheses fol-lowing each label.

The following memory de 'ces be helpful: use pyrCUTto remember that the single-ring •acleotides (pi rimidines) arecytosine, uracil (in RNA), and thyrru . Use purr G to rememberthat the double -ring nucleotides (purin ) are adenine and gua-ni: -e; to help recall the number of hydreg a bonds between theDNA bases, remember that AT = 2 and CC -

6. 3' 1(( ) [p.2191

7.f( ) [p-2191

S.

-ring nitrogen base ( ) [p2191

9. -ring nitrogen base ( ) [p.219 I

10. -ring nitrogen base ( ) [p_219 It

11. -ring nitrogen base

) [p.21

A. The single ring nitrogen base is thyme, by'cau. it hastwo hydrogen bonds.A five-carbon sugar joined to two pithe upright portion of the DNA lad

B.

C.

D.

F.

G.

The single-ring nitrogen baseThe double-ring nitrogen baComposed of three smallnitrogenous base (in thiA chemical group tha

The double-ring nitrogen base is

ins two sugars in the upright portion of the DNA ladder.

se, a single-ring nitrogen base).olecules: a phosphate group, five-carbon deoxyribose sugar;

ine, because it has three hydrogen bonds.adenine, because it has two hydrogen bonds.

nine, because it has three hydrogen bonds.

ihate groups in

Ma tching

Choose the most appropriate answer for each

A.

B.

C.

D_

E.

F.

G.

H.

1.

codon [p.230]

three bases at a time [p.230]

sixty-one [p.230]

the genetic code [p.230]

5. ^c molecular "hook" [p.230]

6.

ribosome [p.231]

anticodon [p.230]

"stop" codons [p.230]

Composed of two subunits, the small subunit with P and A

amino acid binding sites as well as a binding site for mRNA

Reading frame of the nucleotide bases in mRNFAon tRNA, an attachment site for an amino acid

UAA, UAG, UGAA sequence of three nucleotide bases, that can p

vith a specific

m^vti A codonName for each base triplet in mRNNAThe number of codons that actually specify amino acids

Term for how the nucleotide sequences of DNA and then mRNA

correspond to the amino acid sequence of a polypeptide c' .aim

Completion :-

25. Suppose the following line represents the DNA strand that will act as a template for the production of

.RNA through the process of transcription. Fill in the blanks below the DNA strand with the sequence of

complementary bases that will represent the message carried from DNA by mRNA to the ribosome in the

_.cytoplasm [see text Figure 14.8 on pp.228-2291.

)PDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDP

i

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1

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T A C A A G A T A A C A T T A T T T C C T A C C G T C A T C

U

u 1 0 C) U AwNtIOA (lei Rua 6C

v W^IT T T T T T T T T T T T T T T T T T T T T T T T T T T T

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HdHdHdadadHdHdHdadHdddUdadadudHdHdHdadHdUdtidHarldUdFidbdadada

(transcribed single-strand mRNA)

Boldfaced, Page-.Referenced Terms

[p.225] base sequence

nuj-^

[p.225] transcription

-

t

it

[p.225] translation

[p.225] ribonucleic acid, RNA

[p. 26] gel electrophor

UJ-CIf--IUj __L E 4C\

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k