BIOL 3200 Exam 3 (Dr. Mehari - Auburn)

You isolate a piece of DNA from a microorganism you cultivated from your teeth. The piece of DNA is 94 kbp in size and is circular. You sequence it and discover that it contains genes for pili, and antibiotic resistance. What is this piece of DNA?

plasmid

Which of the following is NOT TRUE about plasmids?

- Without them cells will not survive

- They can be transferred horizontally from one cell to another cell

- Found in archaea, bacteria and eukaryotic microbes

- They are usually circular

without them cells will not survive

Which of the following are TRUE about eukaryote genomes?(select all that apply)

- Eukaryotic genomes are circular like archaeal genome

- Generally, Eukaryote genome is larger than bacterial genome

- Eukaryote genome mainly contain noncoding DNA

- Eukaryotic genomes are organised in operon

- Eukaryote chromosome is linear

- generally, eukaryote chromosome is larger than bacterial genome

- eukaryote genome mainly contain noncoding DNA

- eukaryote chromosome is linear

Besides the nucleoid, two other kinds of DNA molecules that may be present in the cytoplasm of a bacterial cell are ________ and ________.

plasmids; bacteriophages genome

Negative supercoiling in bacteria is typically introduced by _______ enzyme and are commonly inhibited by antibiotics called Quinolones.

gyrase

Which of the following is/are TRUE about PCR.

Select all that apply.

- It required DNA ligase

- It requires DNA primers

- It requires DNA polymerase

- It involves Okazaki fragments

- It requires heating

- it requires DNA primers

- it requires DNA polymerase

- it requires heating

The necessary ingredients for PCR reactions are mixed together in a test tube. The DNA polymerase is from Thermus aquaticus, the primers are artificially synthesized and the DNA template is from an E. coli. The newly synthesized DNA would look like _____.

E. coli DNA

Thermostable DNA polymerases are used in PCR because they

can survive at the high temperature used to denature DNA

Which of the following is NOT a product of transcription in bacteria?

- mRNA

- rRNA

- tRNA

- Okazaki fragment

Okazaki fragment

In the process of transcription, promoters are specific sequences found on ________ that are recognized by ________.

DNA template; Sigma factor

All of the following are required during bacterial transcription EXCEPT

- Sigma factor

- Coding DNA strand

- RNA polymerase

- DNA template

coding DNA strand

Which of the following are NOT directly involved in bacterial translation.

Hint: choose more than one. You will be penalized for picking the wrong answer.

- RNA polymerase

- tRNA

- rRNA

- Sigma factor

- mRNA

- RNA polymerase

- Sigma factor

Consider a mutation in which the change is from UAC to UAG. Which type of mutation is this?

nonsense mutation

Bacterial translation involves

30S subunit, tRNA, 50S subunit

UUA - leucine

GCA - alanine

AAG - lysine

GUU - valine

UAG - STOP

AAU - asparagine

UGC - cysteine

UCG - serine

Refer to the table above. What are the amino acids encoded if the sequence of the Coding strand is 5' TTA GCA GTT AAG 3'

Leucine - Alanine - Valine - Lysine

UUA - leucine

GCA - alanine

AAG - lysine

GUU - valine

UAG - STOP

AAU - asparagine

UGC - cysteine

UCG - serine

Refer to the table above. If the sequence of amino acids encoded by a strand of mRNA is asparagine-cycteine-lysine-valine, what is the order of bases in the coding sequence?

5' AAT TGC AAG GTT 3'

T/F All sigma factors compete for the same number of core RNA polymerase enzymes

true

You are analyzing a series of mutants that have defects in either transcription or translation. Which of the following mutations would you predict to impact translation?

- Primase

- Shine-Dalgarno sequence

- 30S subunit

- DNA polymerase

- helicase

- RNA polymerase

- Sigma factor

- 16S rRNA

- Shine-Dalgarno sequence

- 30S subunit

- 16S rRNA

Many pharmaceutical drugs specifically inhibit transcription in Bacteria but not Archaea or Eukarya. Why would drugs that inhibit transcription only affect Bacteria and not Archaea even though they are both prokaryotes?

- Archaea and Eukarya have very similar RNA polymerases that are different from bacterial RNA polymerases.

- Bacteria lack a nucleus.

- Archaea lack operons.

- Archaea and Eukarya have very chromosomes that are different than bacterial ribosomes.

archaea and eukarya have very similar RNA polymerases that are different from bacterial RNA polymerases

During transcription, if the coding strand of DNA has the sequence 3' TCTAGGACT 5', what will the sequence of the transcribed RNA be?

5' UCAGGAUCU 3'

The termination of transcription can be caused by which of the following? Select all that apply.

- Transcription of inverted repeats

- Stop codon

- Release factor

- Rho factor

- transcription of inverted repeats

- rho factor

The fate of newly made bacterial proteins (nascent proteins) are all of the following EXCEPT

- Folded into a 3D structure and remain in the cytoplasm

- Inserted into the cell membrane

- Translated back to mRNA so that they can be recycled

- Exported outside the cytoplasm

translated back to mRNA so that they can be recycled

What is the main difference between a mRNA and tRNA?

only mRNA gets translated to amino acid sequence

Consider an MIC result of 5 μg/ml of penicillin for bacterial strain A, 25 μg/ml for strain B, 15 μg/ml for strain C, and 20 μg/ml for strain D. Which bacterial strain can be interpreted as the most resistant to penicillin?

B

The best target for development of a new antibiotic against Mycobacterium species would be

mycolic acids

Penicillin is less effective when used in combination with ___________________.

bacteriostatic antibiotics

T/F Genes that are part of plasmids are not essential for cell growth

true

All of the following are true about archaea and bacteria, EXCEPT

- Both have polygenic operons

- Both mainly contain single circular chromosome

- Both are equally affected by RNA synthesis inhibitors

- Both lack nuclear membrane

both are equally affected by RNA synthesis inhibitors

T/F DNA that are considered essential for cell growth are usually found in the chromosomes

true

T/F In nature, the predominant form of DNA is positively supercoiled

false

Genetic change in bacteria can be brought about by all of the following, EXCEPT

- mutation

- replication

- conjugation

- transformation

replication

T/F Most bacteria contain one circular chromosome

true

Frederick Griffith used this organism to study DNA mediated transformation

Staphylococcus pneuomoniae

T/F An organism must replicate its chromosome prior to undergoing septation or binary fission

true

Which of the following pairs is mismatched?

- DnaA -- replication initiation protein

- DNA polymerase -- makes a molecule of DNA from a DNA template

- RNA polymerase -- makes a molecule of RNA from RNA template

- DnaB -- unwind double strand DNA

RNA polymerase -- makes a molecule of RNA from RNA template

Which of the following types of mutation types are possible with a deletion or insertion of 1 or 2 nucleotides?

Hint: choose more than one answer

- No mutation

- Frameshift mutation

- Nonsense mutation

- Silent mutation

- frameshift mutation

- nonsense mutation

During what process do you see ringed catenanes form?

End of DNA replication

Which of the following is involved in E. coli replication termination?

- Rho

- Tus protein

- Promoter

- Stop codon

Tus protein

Which of the following about chromosomal DNA replication and plasmid rolling circle replication is true?

- Only chromosome DNA replication require RNA primers

- Only chromosome replication uses DNA polymerase III

- Only chromosome grow 5' to 3' direction

- Only chromosome DNA replication involves Okazaki fragments

only chromosome DNA replication involves Okazaki fragments

T/F Both leading and lagging strands are synthesized 5' to 3' direction

true

All of the following are enzymes involved during bacterial DNA replication EXCEPT

- Primase

- DNA Polymerase III

- Helicase

- Sigma factor

Sigma factor

T/F RNA primer is required in rolling circle replication of plasmids

true

All of the following are TRUE about DNA gyrase EXCEPT

- relieves DNA supercoils

- it is capable of making double strand cut

- it is a type I topoisomerase

- introduces negative supercoil

it is a type I topoisomerase

T/F Just like bacterial chromosome replication, plasmid rolling circle replication involves both leading and lagging strand

false

All of the following are required in a PCR reaction EXCEPT

- DNA polymerase

- DNA ligase

- DNA template

- Primers

DNA ligase

Which of the following is NOT TRUE about PCR

- It requires heat

- It requires DNA primers

- It involves Okazaki fragments

- It requires DNA polymerase

it involves Okazaki fragments

Taq DNA Polymerase is commonly used in Polymerase Chain Reaction (PCR) because

it functions in high temperature environments

Which is NOT TRUE about bacterial transcription?

- Bacterial transcription is different from archaeal transcription

- Requires a separate Helicase enzyme

- Can be affected by Actinomycin D

- Can be affected by Rifamycin B

requires a separate Helicase enzyme

What happens to an E. coli mutant that lacks Sigma -70

transcription of many genes will stop

One of these is not like the others.

- mRNA

- DNA

- tRNA

- tmRNA

mRNA

T/F Transcription use an RNA template while replication use a DNA template

false

Which of the following is NOT a product of transcription in bacteria?

- tRNA

- mRNA

- Sigma factor

- rRNA

Sigma factor

The -35 and -10 site on a promoter are critical site for ___

transcription

T/F Changes during transcription can have long lasting effects on the upcoming generations

false

All of the following are involved in bacterial transcription EXCEPT

- Sigma factor

- RNA transcription

- Promoters

- RNA primers

RNA transcription

What is NOT TRUE about promoter sequences in bacterial transcription

- recognized by sigma factor

- located on the transcribed RNA

- located on the DNA template

- located upstream of the transcription start sire

located on the transcribed RNA

DNA template for a bioB gene is below, what will be the sequence of the RNA transcript for that specific gene?

+1 - TACACCGAAT

5' AUGUGGUUA 3'

All of the following are required during bacterial transcription EXCEPT

- Sigma factor

- RNA polymerase

- DNA template

- Coding DNA strand

coding DNA strand

Termination of RNA synthesis is ultimately determined by

Hint: choose two answers

- specific nucleotide sequences on the template strand

- Rho protein

- specific nucleotide sequences on the coding strand

- Tus protein

- specific nucleotide sequences on the template strand

- Rho protein

Which is NOT TRUE about bacterial ribosomes?

- contains rRNA

- have 2 subunits

- they find the right reading frame via the Shine-Dalgarno sequence

- they find the right reading frame by the help of promoter sequence

they find the right reading frame by the help of promoter sequence

Why coupling of translation and transcription is impossible in eukaryotes?

because transcription and translation are separated by nuclear membrane

All are directly involved during bacterial translation EXCEPT

- tRNA

- rRNA

- mRNA

- Sigma factor

Sigma factor

T/F Shine Dalgarno sequences are complementary to the 3' end of 16S rRNA in E. coli

true

UUA - leucine

GCA - alanine

AAG - lysine

GUU - valine

UAG - STOP

AAU - asparagine

UGC - cysteine

UCG - serine

Refer to the table above. If the sequence of amino acids encoded by a strand of mRNA is serine-alanine-lysine-leucine, what is the order of bases in the coding sequence?

5' TCGGCAAAGTTA 3'

UUA - leucine

GCA - alanine

AAG - lysine

GUU - valine

UAG - STOP

AAU - asparagine

UGC - cysteine

UCG - serine

Refer to the table above. If the sequence of amino acids encoded by a strand of mRNA is asparagine-cysteine-lysine-valine, what is the order of bases in the coding sequence?

5' AAT TGC AAG GTT 3'

Match the list of words with their function

- Shine Dalgarno sequence

- Sigma-70

- SeqA

- DnaA

- -35 and -10

- DNA replication initiation protein

- Ribosome binding site

- Signals the beginning of the gene

- DNA replication inhibitor

- Shine Dalgarno sequence -- ribosome binding site

- Sigma-70 -- -35 and -10

- SeqA -- DNA replication inhibitor

- DnaA -- DNA replication initiation protein

A bacterial strain exhibiting a mutation on the A site of the ribosome would most likely resist the activity of what class of antibiotics?

tetracycline

This antibiotic is known to inhibit RNA synthesis in bacteria

rifamycin D

Which of the following is/are product(s) of transcription?

- Polycistronic RNA

- mRNA

- tRNA

- Monocistronic RNA

- All are products of transcription

all are products of transcription

You produced a strain of Salmonella that completely lacks sigma factors it would fail to grow because

- No replication

- No translation

- No transcription

- It would survive fine since sigma factors are not required for growth

no transcription

UUA - leucine

GCA - alanine

AAG - lysine

GUU - valine

UAA - STOP

AUG - methionine

UGC - cysteine

UCG - serine

Refer to the table above. If the sequence of amino acids encoded by a strand of mRNA is methionine-serine-cysteine-valine, what is the order of bases on the mRNA?

5' AUG UCG UGC GUU 3'

If the order of bases in the mRNA is 5' AUG UCG UGC GUU 3', what is the order of bases in the template DNA strand?

3' TAC AGC ACG CAA 5'

UUA - leucine

GCA - alanine

AAG - lysine

GUU - valine

UAA - STOP

AUG - methionine

UGC - cysteine

UCG - serine

Refer to the table above. What is the sequence of amino acids if the coding DNA sequence is 5' TAA TGC AAG TAA 3'

translation would stop at the first codon

This enzyme is responsible for filling gaps left after RNA primers are removed from Okazaki fragments

DNA polymerase I

T/F In general, bacterial genomes are smaller than eukaryotic genomes

true

T/F Sexual reproduction is the only mechanism for genetic change

false

T/F In prokaryotes, several ribosomes can simultaneously translate a single mRNA molecule

true

T/F Bacteria and archaea usually have double-stranded circular DNA genomes

true

T/F The best target for development of a new antibiotic would be the enzymes of the glycolysis pathway

false

T/F Penicillin is less effective when used in combination with bacteriostatic antibiotics

true

Selman Waksman won the Nobel prize for the discovery of

streptomycin

DNA gyrase is required in

transcription and replication

Which of the following is usually found as integral part of ribosomes?

- tRNA

- mRNA

- rRNA

- sRNA

rRNA

Which of the following is NOT TRUE to both codons and anticodons

- they are both RNA sequences

- are sequences of DNA three nucleotides long

- codon is found in mRNA while anticodon in tRNA

- are complementary RNA sequences

are sequences of DNA three nucleotides long

What does it mean to say that the genetic code is redundant?

more than one codon can specify the same amino acid

The significance of the promoter sequence in DNA is the site where

RNA polymerase binds to begin transcription

Negative supercoiling in bacteria is typically introduced by enzymes called

gyrases

A bacteria may be penicillin resistant due to all of the following EXCEPT

- a Gram-negative cell wall

- beta-lactamase production

- a Gram-positive cell wall

- modified transpeptidases

- modified transglycosylases

a Gram-positive cell wall

Scientists are concerned that bacteria will be resistant to all antibiotics within the next decade. Based on the information discussed in class, why will bacterial populations develop drug resistance in such a short time frame?

- Bacteria can accept foreign plasmid

- Bacteria are exposed to antibiotics all the time

- All bacteria have resistance genes in their genome that can easily be activated

- Only a and b are correct

- a, b, and c are correct

only a and b are correct

Only prokaryotes are able to do this process because they lack membrane bound organelles

coupling of transcription and translation

Which of the following pairs is mismatched?

- DNA polymerase -- makes a molecule of DNA from a DNA template

- RNA polymerase -- makes a molecule of RNA from an RNA template

- DNA ligase -- joins segments of DNA

- DNA gyrase -- introduce supercoils to DNA

RNA polymerase -- makes a molecule of RNA from an RNA template

Plasmids

- found in archaea, bacteria, and eukaryotic microbes

- contain information for glucose metabolism

- can only be transferred vertically

- are usually linear pieces of information

found in archaea, bacteria, and eukaryotic microbes

The necessary ingredients for DNA synthesis can be mixed together in a test tube. For a successful PCR reaction, all of the following are required except

- Both forward and reverse primers

- Taq DNA polymerase

- DNA template

- All four DNA nucleotides

- All of the above are required

all of the above are required

What is the main reason behind replicating one strand of DNA in Okazaki fragments

- DNA polymerase can only add nucleotides to the 3' end

- DNA replication is semiconservative, and each strand is copied simultaneously in opposite directions

- one strand of DNA is copied faster than the other

- choices a and b are the main reasons

- choices a, b, and c are the main reasons

choices a and b are the main reasons

Many pharmaceutical drugs specifically inhibit transcription in Bacteria but not in Archaea or Eukarya. Why would drugs that inhibit transcription only affect Bacteria and not Archaea even though they are both prokaryotes?

archaea RNA polymerases are different from bacterial RNA polymerases

These are all different ways a bacterium can become resistant to antibiotics EXCEPT

- By modifying the target on the bacterium

- By modifying the antibiotics to make it inactive

- By making enzymes that destroy antibiotics

- By avoiding the antibiotics

- By pumping antibiotics out of the bacteria

by avoiding the bacteria

Which of the following is correct regarding DNA and RNA synthesis?

- The overall direction of chain growth is from the 3' to 5' end

- Both processes require an RNA primer to begin

- The template strand is parallel to the newly synthesized strand

- DNA is the template for both DNA and RNA synthesis

DNA is the template for both DNA and RNA synthesis

How are plasmids similar to chromosomes?

- Like chromosomes, plasmids are always linear pieces of DNA

- Like chromosomes, plasmids are composed of double-stranded DNA

- Like chromosomes, plasmids contain genes that are essential for cellular growth and replication

- Like chromosomes, one strand of the plasmid gets copied in fragments

like chromosomes, plasmids are composed of double-stranded DNA

Proteins destined for cell membrane have signal sequences that binds to signal recognition particle

- at the 3' end

- at the 5' end

- in the 50S ribosomal subunit

- at the C-terminus

- at the N-terminus

at the N-terminus

An antibiotic that is a folic acid synthesis inhibitor is

sulfonamides