Microbio Test 3

During translation, what is the function of the A site of the ribosome?

It binds to the tRNA carrying the next amino acid

Which of the following statements is true about the leading strand during DNA replication?

It is synthesized continuously

Which enzyme seals the gaps between Okazaki fragments during DNA replication?

Ligase

What is the main difference between prokaryotic and eukaryotic translation initiation?

Eukaryotes use the Kozak sequence for ribosome binding.

A pure culture of E. coli is being grown in media with both glucose and lactose. How is the Lac operon being regulated?

There is a low level expression of the lac operon because CAP cannot bind and Allolactose binds and removes the repressor.

In prokaryotic transcription, what is the function of the sigma factor?

It facilitates RNA polymerase binding to the promoter

In prokaryotes, where does translation occur?

In the cytoplasm

Which enzyme catalyzes the formation of peptide bonds during translation?

Peptidyl transferase

Which molecule directly participates in both transcription and translation in prokaryotes?

mRNA

Which of the following is an example of an induced mutagen?

UV radiation causing thymine dimers

Which of the following is a difference between prokaryotic and eukaryotic DNA replication?

Eukaryotes replicate their DNA in a linear fashion

Where does translation occur in eukaryotic cells?

Cytoplasm

When splicing pre-mRNA, what is the main goal?

To remove all introns and to keep all exons

In eukaryotic DNA replication, this polymerase works on the lagging strand

Dna Pol delta

In prokaryotic transcription, what is the outcome if the sigma factor is mutated?

RNA polymerase will not bind the promoter

What is the function of the ribosome during translation in prokaryotes?

Facilitates the synthesis of proteins by linking amino acids together

What is the significance of the -10 and -35 regions in prokaryotic transcription?

They are the binding sites for RNA polymerase

Which protein is responsible for relieving the supercoiling of DNA ahead of the replication fork?

Topoisomerase

Produces multiple polycistronic mRNA

Regulon

Contains multiple genes but only one promoter and terminator

operon

Needs a regulatory protien to be activated

Regulon

Produces a single polycistronic mRNA

Operon

Produces a single monocistronic mRNA

Gene

Contains multiple operons

Regulon

Does not result in a polyribosome

gene

Used to create one polyribosome structure

operon

Synthesizes mRNA 5'->3' during elongation step

RNA Polymerase

Removable part of RNA polymerase that allows it to bind the promoter

Sigma Factor

A hairpin loop causes RNA polymerase to fall off the DNA

Transcription Termination

Coding Strand

Sense (+) strand

Template strand

Antisense (-) strand

RNA polymerase uses this as a base to synthesize mRNA

Template Strand

The genetic code that is to become a protein is found here

Coding Strand

Here is the part of the promoter where RNA polymerase binds

-35 sequence

Here is the part of the promoter where RNA polymerase starts separating the DNA

-10 sequence

A hairpin loop causes RNA polymerase to fall off the DNA

Transcription termination

Every three nucleotides

codon

The way a ribosome reads the mRNA nucleotides

reading frame

Binds to mRNA first

30S ribosome subunit

Binding to this helps the ribosome find the start codon and its reading frame

Shine-Dalgarno sequence

Uses anticodon binding to bring aminoacids to the ribosome

Transfer RNA (tRNA)

Receives the tRNA first via codon interaction

A-site

Peptide bonds are formed between amino acids at this site

P-site

tRNAs leave once they enter this site

E-site

The only protein to recognize the stop codon and cause the ribosome to stall

In prokaryotes, transcription and translation can be coupled because: 

The mRNA does not undergo processing before translation. 

In prokaryotic translation, what is the primary function of the large ribosomal subunit? 

It catalyzes the formation of peptide bonds between amino acids.

Prokaryotic mRNAs are often polycistronic, which means: 

They encode multiple proteins that are translated from a single mRNA molecule.

Which statement accurately describes the charging of tRNA and its role in translation? 

tRNAs have regions called amino acid attachment sites that attach to the corresponding amino acid.

During prokaryotic transcription, what is the function of RNA polymerase's core enzyme (without the sigma factor)? 

It synthesizes RNA by adding nucleotides complementary to the DNA template strand. 

Which mechanism is responsible for the termination of transcription in prokaryotes? 

Rho-dependent termination involving the rho protein. 

How does the anticodon of a tRNA molecule contribute to the accuracy of translation? 

It signals the termination of translation at the stop codon.

initiation of translation in prokaryotes

The Shine-Dalgarno sequence in the mRNA aligns with the 16S rRNA in the small ribosomal subunit. 

transcriptional machinery in prokaryotes

The sigma factor in prokaryotes binds to the -35 and -10 regions of the promoter to initiate transcription. 

Dna gyrase

DNA elongation

DNA primase

DNA elongation

DnaC

DNA replication initiation

DNA polymerase III

DNA elongation

DnaB

DNA replication initiation

Topoisomerase IV

DNA replication termincation

DnaG

DNA elongation

OriC

DNA replication initiation

DNA Pol. I

DNA elongation

DNA ligase

DNA elongation

SSB

DNA elongation

DnaA

DNA replication initiation

Ter

DNA replication termination

Tus

DNA replication termination

RNaseH

DNA elongation

Binding site of the initiator and site of initial replication bubble

OriC

The initiator

DnaA

Involved in DNA repair

DNA polymerase I

Synthesizes new DNA

DNA polymerase III

Helicase

DnaB

Helicase loader

DnaC

Primase which creates a primer from which DNA polymerase can start synthesizing

DnaG

Binds newly separated DNA to stop them from coming back together

SSB

Releases super coiling pressure on rest of DNA

DNA gyrase

Involved in DNA repair

DNA polymerase I

Removes primers put down by primase

RNase H

function of primase in prokaryotic DNA replication

Primase synthesizes short RNA primers that are necessary for DNA polymerase to initiate DNA synthesis. 

prokaryotic DNA replication, which of the following best describes the function of DNA polymerase III

It elongates the RNA primer by adding DNA nucleotides in the 5’ to 3’ direction. 

proofreading activity of DNA polymerase III in prokaryotic DNA replication

DNA polymerase III has 3’ to 5’ exonuclease activity to remove mismatched nucleotides. 

prokaryotic DNA replication, what is the role of the Tus protein in the termination process

Tus protein binds to termination sites (Ter sites) and prevents the advancement of the replication fork. 

primary function of the helicase enzyme in prokaryotic DNA replication

To unwind the double-stranded DNA helix.

role of DNA ligase in prokaryotic DNA replication

DNA ligase joins Okazaki fragments by forming phosphodiester bonds

synthesis of the leading and lagging strands in prokaryotic DNA replication

The leading strand is synthesized continuously, while the lagging strand is synthesized in short discontinuous fragments. 

encodes for functional polypeptide

exons

Do not encode for functional polypeptide

introns

mRNA signal for exportation and ribosome recognition

5’ cap

mRNA degradation protection

3' poly-A tail

Initiates DNA replication

ORC

Primase

DNA pol alpha

Lagging strand polymerase

DNA pol delta

Leading strand polymerase

DNA pol epsilon

Extends 3' end of parent strand

Telomerase

Small ribosome uses this to locate start codon

Kozak sequence

DNA pol epsilon

Eukaryotic

Replication, transcription bubble

In both cells

Sigma factor

Prokaryotic