Exam 4 Review

Question 1

Which of the following is not a similarity between the replicative DNA polymerase and the RNA polymerase used in transcription?
a. both require nucleoside triphosphates
b. both polymerize in the 5’ to 3’ direction
c. both require templates
d. both require primers to initiate new strand synthesis
e. all of the above are traits of both
f. none of the above are shared traits

Answer 1

d

Question 2

which of the following is not true of bacterial translation?
a. the process is energy-demanding, but done more quickly compared to eukaryotes
b. the first tRNA is placed within the P site of the ribosome of the 50S subunit
c. 23S rRNA is responsible for catalyzing the transpeptidation
d. fewer initiation/elongation factors are used as compared to eukaryotes
e. all of the above are true
f. none of the above are true

Answer 2

e

Question 3

T/F: in bacteria there tends to be one sigma factor used for transcription, but alternative factors are usually required for special circumstances

Answer 3

true

Question 4

T/F: all 64 codons of the genetic code encode for amino acids

Answer 4

false

Question 5

T/F: 5S rRNA is found in the large ribosomal subunit of both prokaryotes and eukaryotes

Answer 5

true

Question 6

T/F: polysomes are observed in all three domains to improve the efficiency of translation

Answer 6

true

Question 7

Important to the DNA replication process is separating two strands of the DNA chromosomes; please provide the 3 proteins within the replisome that are imperative in this role.

Answer 7

origin binding proteins
single stranded binding proteins
helicases

Question 8

In bacteria, how is DNA polymerase I different in enzymatic activity from DNA polymerase III?

Answer 8

DNA polymerase I uses 5’ to 3’ exonuclease activity

Question 9

To complete the replication of a bacterial chromosome __________ proteins bind to _________ sites that are found on the opposite side of the chromosome from the origin of replication. Ultimately, the chromosomes are separated and bind to _______, a component within the divisome

Answer 9

Tus
Ter
FtsK

Question 10

Plasmids replicate using the ________________ method

Answer 10

rolling circle

Question 11

The consensus sequence, TATAAT, located _______ (#) bases upstream of the bacterial transcription start site is called the _____________. a second consensus sequence _______, is located 35 bases upstream of the bacterial transcription start site.

Answer 11

10
Pribnow box
GGTACA

Question 12

T/F: archaeal microorganisms contain these same promoter sequences for thei transcriptional processes

Answer 12

False

Question 13

In the intrinsic method of terminating transcription, the DNA at the end of the gene will be GC-rich and contain inverted repeats followed by a stretch of adenines - how do these sequences affect mRNA structure and contribute to the termination of transcription?

Answer 13

Hydrogen bonding between GC rich segments within the mRNA sequence forms a hairpin loop which destabilizes the interaction between RNA polymerase and the RNA transcript.
The inverted repeats on the RNA form a stem loop structure that further stabilizes the hairpin formation. In the transcribed RNA, there is a stretch of uracils (as a result of transcribing adenine). This forms a poly-U which destabilizes the RNA polymerases interaction with the DNA template.

Question 14

One unique characteristic regarding bacterial mRNA is that it is ________ which means it contains multiple genes. Please explain how the eventual proteins are seperated?

Answer 14

polycistronic

Question 15

Please provide three characteristics that define mRNA transcripts within eukaryotes but are not shared by bacteria

Answer 15

monocistronic
3’ end (Poly A tail)
5’ cap (7-methylguanosine)

Question 16

________________ are the enzymes responsible for charging individual tRNA molecules with the appropriate amino acid. The amino acid is always added to the 3’ acceptor site which ends with the sequence ____________

Answer 16

aminoacyl-tRNA synthetase
CCA

Question 17

Provide one reason why tRNA is more stable than mRNA

Answer 17

the secondary (clover leaf) structure with intradomain bends

Question 18

The shine dalgarno sequence is located within the __________ of the mRNA transcript at the ___ end

Answer 18

leader sequence
5’

Question 19

what does the shine-dalgarno sequence specifically bind to?

Answer 19

5’ end of 16S rRNA

Question 20

T/F: the Shine-Dalgarno sequence is uniquely found within prokaryotes

Answer 20

True

Question 21

T?F: IF-3 binds to the large ribosomal subunit to prevent it binding the small subunit too early

Answer 21

false

Question 22

what are the two roles of IF-2 in the initiation of bacterial translation

Answer 22

Brings the first tRNA to the P site
Binds GTP and guides it to the 30S subunit to be hydrolyzed once the 50S subunit is bound, allowing the initiation complex to be formed

Question 23

Please explain how tRNAs are brought into the A site during bacterial translation (you must provide the correct elongation factors and thei roles)

Answer 23

EF-Tu will bring the tRNA into the A site, and GTP will be recycled by EF-Ts. The 23S rRNA will complete the peptid linkage and EF-G will facilitate translocation of the ribosome to the P site

Question 24

T/F: bacterial proteins begin to fold before the peptide synthesis is complete while eukaryotes tend to wait until synthesis is finished

Answer 24

False

Question 25

what happens if a protein cannot be folded after interacting with DnaK and DnaJ then proteins are shuttled to a system involving _________ and _________

Answer 25

Gro-EL
Gro _ ES

Question 26

How is the Gro-Es and Gro-EL secondary system, structurally/functionally different than the DnaK/DnaJ system?

Answer 26

DnaK and DnaJ act as clips and bite down while Gro-ES will move proteins in and Gro-EL will force shape

Question 27

What is one similarity of the DnaK/DnaJ and GroEs/GroEL systems?

Answer 27

both use ATP

Question 28

The starting point for bacterial DNA replication is the origin of replication which has a sequence that is 250 base pairs long and is __________ - rich. Next DnaB and DnaC will bind and these are the __________ and the _____________. what are the next two proteins that bind before any synthesis begins? please explain the role/importance of each

Answer 28

Adenine/Thymine
helicase
helicase loader
topoisomerase - enzyme that helps untwist DNA
Single-stranded binding proteins - stabilizes separated strands

Question 29

How do the three domains differ in terms of the number of origins found within a chromosome?

Answer 29

bacteria: 1
Eukarya: many
Archaea: a few

Question 30

T/F: DnaB and DnaC are highly conserved within prokaryotes

Answer 30

False

Question 31

There are ______ (#) different DNA polymerases in bacteria. The main replicative enzyme is known as DNA polymerase _____. This main replicative enzyme is categorized within the _____ family of DNA polymerases

Answer 31

5
III
C

Question 32

Which of the following is not true of bacterial replication?
a. just as seen in eukaryotes, they practice semiconservative replication
b. DNA ligase is needed to make final connection after primer removal
c. to terminate the process, tus proteins bind to ter sites that are next to the origin of replication
d. a topoisomerase is needed to unlink the two circular chromosomes
d. to insure one chromosome into each cell, each chromosome binds to an ftsK protein on either side of theftsZ ring
e. all of the above
f. none of the above

Answer 32

C

Question 33

t/F: DNA polymerase has 5’ to 3’ exonuclease activity to help limit the placement of a wrong base

Answer 33

False