Chapter 14: From DNA to Protein

Question 1

transcription

Answer 1

copies information from a DNA sequence (a gene) to a complementary DNA sequence

Question 2

translation

Answer 2

converts RNA sequence to amino acid sequence of a polypeptide

Question 3

Messenger RNA

Answer 3

mRNA, carries copy of DNA sequence to site of protein synthesis at the ribosome

Question 4

Transfer RNA

Answer 4

tRNA, carries amino acid for polypeptide assembly

Question 5

Ribosomal RNA

Answer 5

rRNA, catalyzes peptide bonds and provides structure

Question 6

messenger hypothesis

Answer 6

mRNA forms as a complementary copy of one DNA strand in a gene

Question 7

RNA polymerases

Answer 7

catalyze the synthesis of RNA (does not need primers)

Question 8

3 stages of transcription

Answer 8

Initiation
Elongation
Termination

Question 9

promoter

Answer 9

a special sequence of DNA, that tells RNA polymerase where to start and which strand of DNA to transcribe

Question 10

Elongation

Answer 10

RNA polymerase unwinds DNA about 10 base pairs at a time reads template in 3’ to 5’ direction

Question 11

Termination

Answer 11

specified by DNA base sequence

Question 12

genetic code

Answer 12

specifies which amino acid will be used to build a protein

Question 13

codon

Answer 13

a sequence of 3 bases, which each code for an amino acid

Question 14

Start codon

Answer 14

AUG– Invitation signal for translation

Question 15

Stop codons

Answer 15

UAA, UAG, UGA– stop translation and polypeptide is released

Question 16

ribosome

Answer 16

the workbench– holds mRNA and charged tRNAs in correct positions to assemble polypeptide chain

Question 17

3 steps of translation

Answer 17

initiation
elongation
termination

Question 18

translation initiation

Answer 18

a charged tRNA and small ribosomal subunit both bound to mRNA, large subunits join’s the complex; the charged tRNA us now in the P site of the large subunit

Question 19

translation elongation

Answer 19

the second charged tRNA enters the A site.
Large subunit catalyzes 2 reactions:
- it breaks bind between tRNA in P site and its amino acid
- peptide bond forms between that amino acid and amino acid on tRNA in the A site

Question 20

translation termination

Answer 20

translation ends when a stop codon enters the A site

Question 21

protein modifications

Answer 21

proteolysis by proteases, Glycosylation– adding sugars to form glycoprotein. Phosphorilation– adding phosphate groups by kinases