Chapter 15 Translation

Question 1

If mRNA is 5’AUGCGA 3’, infer the sequence of bases on the
DNA coding strand.

Answer 1

a.5’ ATGCGA 3’

Question 2

RNA polymerase II moves along the template strand of DNA in the _____ direction, and adds nucleotides to the ___ end of the growing transcript of mRNA.

Answer 2

a.3’ to 5’; 3’

Question 3

A spliceosome’s function in prokaryotic mRNA is to excise introns and splice exons. True or False.

Answer 3

False

Question 4

In the genetic code, one codon

a. consists of 3 bases
b. specifies a single amino acid
c. specifies more than one amino acid
d. Both a and b
e. Both a and c

Answer 4

d

Question 5

A prokaryotic gene that is 600 nucleotide
base-pairs in length would code for a polypeptide chain of ______amino acids.

Answer 5

200

Question 6

Operons are common

Answer 6

in prokaryotes

Question 7

Several geners in a sequence all controlled by a single promoter

Answer 7

Operon

Question 8

term for the 3-base coding sequence on the mRNA is a

Answer 8

codon

Question 9

The 3 base coding sequence of a tRNA molecule is an

Answer 9

anticodon

Question 10

attaches the correct amino acid to its corresponding tRNA molecule

Answer 10

enzyme catalyzed reaction

Question 11

•are enzymes that catalyze the reaction that attaches the correct amino acid to the acceptor end of tRNA

Answer 11

tRNA synthetases

Question 12

HOW DOES THE AMINO ACID TRYPTOPHAN GET ATTACHED TO THE CORRECT tRNA?

Answer 12

Each of the aminoacyl-tRNA synthetase enzymes is highly specific for a given amino acid.

Question 13

the only molecules in biology that “know” the genetic code.

Answer 13

aminoacyl-tRNA synthetases are

Question 14

the protein assembly organelle of all cells

Answer 14

ribosomes

Question 15

Composition of a ribosome is

Answer 15

65% rRNA and 35% ribosomal proteins

Question 16

How many binding sites does a ribosome have for tRNAs?

Answer 16

3 (EPA)

Question 17

–binds an aminoacyl t-RNA (the charged tRNA carrying the next amino acid)

Answer 17

A site

Question 18

–binds a peptidyl-tRNA (a tRNA bound to the polypeptide being synthesized)

Answer 18

P site

Question 19

–E site – “exit” site–binds an “empty” tRNA before it exits the ribosome

Answer 19

E site

Question 20

3 main phases of Tranlation

Answer 20

initiation, elongation, and termination

Question 21

Initiation of ranslation in prokaryotes

Answer 21

In prokaryotes, initiation of translation requires the formation of the initiation complex including:

1) an initiator tRNA-(fMet)
2) the small ribosomal subunit
3) an mRNA strand

Question 22

Step 1 of elongation in prokaryotes

Answer 22

–STEP 1: MATCHING tRNA anticodon with mRNA codon

–an aminoacyl tRNA binds to the A site–its anticodon is complementary to the mRNA codon at the A site

–REQUIRES ENERGY

Question 23

Step 2 of Elongation in Prokaryotes

Answer 23

PEPTIDE BOND FORMATION

The enzyme peptidyl transferase forms a peptide bond between the two amino acids

Question 24

The enzyme that forms a peptide bond between the two amino acids

Answer 24

peptidyl transferase

Question 25

Step 3 of elongation in translation in prokaryotes

Answer 25

–TRANSLOCATION: the ribosome moves down the mRNA in the 5’ → 3’ direction (to the right) and the initial tRNA (now “empty”) is ejected

Question 26

are recognized by release factors which release the polypeptide from the ribosome.

Answer 26

stop codons

Question 27

a natural process that changes the
DNA sequence or chromosomal structure

Answer 27

Mutation

Question 28

•alter a SINGLE base

Answer 28

Point Mutation

Question 29

Three types of point mutations

Answer 29

1) Base Substitution

–2) base deletion

–3) base addition

Question 30

3 types of base substitution

Answer 30

–Silent mutation

–Missense mutation

–Nonsense mutation

Question 31

•no change occurs to amino acid sequence

Answer 31

silent mutation

Question 32

•causes a change in an amino acid—varying degrees of effects depending on change

Answer 32

missense mutation

Question 33

creates a stop codon

Answer 33

nonsense mutations

Question 34

Frameshift mutations

Answer 34

base deletion

base addition

Question 35

–caused by indels (insertions or deletions) of a number of nucleotides in a DNA sequence that is not divisible by three.

Answer 35

frameshift mutations

Question 36

change he structure of a chromosome

Answer 36

deletions, duplications, incersion, translocation

Question 37

–part of chromosome is lost

Answer 37

deletions

Question 38

–part of chromosome is copied

Answer 38

duplication

Question 39

–part of chromosome in reverse order

Answer 39

Inversion

Question 40

–part of chromosome is moved to a new location

Answer 40

Translocation