Quiz 15 - Lost in translation Flashcards Preview

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Flashcards in Quiz 15 - Lost in translation Deck (30):
1

The genetic code is ______ and ______

universal and overlapping.

universal and non-overlapping.

almost universal and overlapping.

almost universal and non-overlapping.

Almost universal and non-overlapping

2

Which of the following statements about transfer RNAs is TRUE?

A)They have a secondary structure that is represented by a clover-leaf
B)They carry amino acids at their 3' ends
C) Both A and B
D) Neither A nor B

Both A and B

3

How many different sequences of nine ribonucleotides would code for the amino acid combination trp-leu-phe ?
3
6
8
10
none of these choices

None of these choices

Possible code combinations are 12
UGG-UUA- UUU
UGG-UUG- UUU
UGG-CUU-UUU
UGG-CUC-UUU
UGG-CUA-UUU
UGG-CUG- UUU

UGG-UUA- UUC
UGG-UUG- UUC
UGG-CUU- UUC
UGG-CUC- UUC
UGG-CUA- UUC
UGG-CUG- UUC

4

The genetic code is degenerate. This means that?
A) similar amino acids have similar codes
B)one codon can code for more than one amino acid
C) more than one codon can specify the same amino acid
D) one codon can be recognized by more than one tRNA
E) one codon can be part of two or more genes

C) more than one codon can specify the same amino acid

5

What is the role of EF-Tu during bacterial translation?
A) binds to the small ribosomal subunit to initiate translation
B) dissociates monosomes into subunits following termination
C) brings aminoacyl-tRNA to the A site
D) brings aminoacyl-tRNA to the P site
E) stimulates translocation

C) Brings aminoacyl-tRNA to the A site

6

True or False. The formation of a peptide bond is accompanied by the release of a water molecule.

True

7

RF1, RF2 and RF3 participate in?
translation initiation in bacteria
Correct!
A translation termination in bacteria
B translation initiation in eukaryotes
C translation elongation in eukaryotes
D translation termination in eukaryotes

The translation termination in bacteria

8

Which of the following best describes bacterial ribosomes?
A) 30S + 50S = 80S
B) 30S + 50S = 70S
C) 30S + 40S = 70S
D) 40S + 60S = 80S
E) 40S + 60S = 70S

B) 30S + 50S = 70S

9

The following DNA fragment contains the sequence for the translation initiation codon usually used in genes:
CGGAACATCGC
GCCTTGTAGCG


The template strand must be:
A) upper strand, 3'-to-5' from left to right
B) upper strand, 5'-to-3' from left to right
C) lower strand, 3'-to-5' from left to right
D) lower strand, 5'-to-3' from left to right

B) Upper strand, 5' to 3' from left to right

10

The following mRNA sequence codes for the entire (although short) polypeptide. What is the most likely sequence?
5' AGU CGU GGC AUG CCU GAG CGA ACU GUA UGA ACG 3'

A) Ser-Arg-Gly-Met-Pro-Glu-Arg-Thr-Val-Trp-Thr
B) Ser-Arg-Gly-Met-Pro-Glu-Arg-Thr-Val
C) Met-Pro-Glu-Arg-Thr-Val-Trp-Thr
D) Met-Pro-Glu-Arg-Thr-Val
E) None of the above

D) Met- Pro- Glu- Arg - Thr- Val - Trp- Thr

11

Which type of nucleic acid is most likely to contain modified bases?
A) DNA
B) mRNA
C) tRNA
D) two of the above
E) all of the above

C) tRNA

12

During translation, the growing polypeptide chain is transferred from the I site of the ribosome to the next amino acid in the II site. With I site being ___ and II site being ___
A) I = A ; II = P
B) I = E ; II = P
C) I = P ; II = A
D) I = E ; II = A
E) I = P ; II = E

C) I = P ; II = A

13

A round of translation is terminated when the ribosome encounters a stop codon. This is because?
A) the charged tRNA for the stop codon signals the ribosome to stop.
B) there are too many tRNAs for the stop codon.
C) there are not enough tRNAs for the stop codon.
D) there are no tRNAs for the stop codon.

D) there are no tRNAs for the stop codon

14

Which of the following DNA sequences encodes a stop codon?
A) 5′ ATA 3′
B) 5′ TAC 3′
C) 5′ CTA 3′
D) 5′ CAT 3′
E) none of the above

C) 5' CTA 3

15

During translation, mRNA is read in the direction and polypeptides are synthesized from the terminus.
A) 3'-to-5' ; amino to the carboxyl
B) 3'-to-5' ; carboxyl to the amino
C) 5'-to-3' ; amino to the carboxyl
D) 5'-to-3' ; carboxyl to the amino

C) 5'-to-3' ; amino to the carboxyl

16

The genetic code consists of ______ nonsense condon(s)?
A) 1
B) 3
C) 46
D) 61
E) 64

B) 3

17

During translation, peptide bonds are created by a(n) _____ _____called peptidyl .
A) enzyme ; synthetase
B) enzyme ; transferase
C) rRNA ; synthetase
D) rRNA ; transferase
E) none of the above is true

D) rRNA ; Transferase

18

Which of the following does NOT reach the cytoplasm of eukaryotes?
A) exon
B) intron
C) tRNA
D) rRNA
E) two of the above

B) Intron

19

A mature tRNA molecule contains how many stems and loops?

4 stems and 3 loops

20

The enzyme amino acyl-tRNA synthetase does what?
A) Synthesizes tRNA.
B) Destroys excess tRNAs.
C) Attaches the appropriate amino acid to its tRNA.
D) Removes the amino acid from its tRNA during of translation
E) Helps tRNA synthesize amino acids

C) Attaches the amino acid from its tRNA during of translation

21

Immediately after the peptide bond forms and prior to translocation of the ribosome, the amino acids are attached to the:
A) A site
B) P site
C) E site
D) A and P sites
E) A, P and E sites

A site

22

During translation, each time the ribosome moves down the mRNA three nucleotide bases, the old _I_ site becomes the new _II_ site. With I site being __ and site II __
A) I = A ; II = P
B) I = P ; II = A
C) I = E ; II = A
D) I = E ; II = P
E) none of the above is true

I = A ; II = P

23

The __________ is a structure consisting of many ribosomes translating the same mRNA a different sites at the same time.

polysome

24

Which of the following code for amino acids?
Intron
Ion
Exon
Exxon
Enron

Exon

25

To construct protiens, organisms use ____ naturally occuring amino acids.
3
20
46
61
64

20

26

True or false. An open reading frame (ORF) is a sequence of DNA that is likely codes for a polypeptide

False
An ORF is the length of a nucleotide sequence between a start and a stop codon

27

The coupling of transcription and translation is possible in prokaryotes but NOT in eukaryotes because?

A) the transcription speed in prokaryotes is higher than that in eukaryotes.
B) the translation speed in prokaryotes is higher than that in eukaryotes.
C) transcription and translation occur in one cellular compartment in prokaryotes,
but in separate cellular compartments in eukaryotes.

The coupling of transcription and translation is possible in prokaryotes but NOT in eukaryotes because
Transcription and translation occur in one cellular conpartment in prokaryotes, but in separate cellular compartments in eukaryotes

28

During protein synthesis in bacteria, _______ catalyzes the translocation step

EF-G

29

In bacteria, the initiator tRNA carries ______ and it enters through the ______ site of the ribosome

N-formylmethionine; P

30

Cleavage of ______ provides the chemical energy for loading the aminoacyl tRNA onto the ribosome, an cleavage of _____ is the energy source that drives ribosomal translocation

GTP; GTP