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BIOL 321 > Bacterial Cytoplasmic Structures > Flashcards

Bacterial Cytoplasmic Structures Flashcards

1
Q

Which of the following statements about the bacterial nucleoid is incorrect?
A) It is usually not membrane-bound.
B) It contains a closed circular, double-stranded DNA molecule.
C) Supercoiling and nucleoid proteins aid in folding.
D) It consists of multiple linear chromosomes.

A

D) It consists of multiple linear chromosomes.

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2
Q

Which of the following is true regarding bacterial ribosomes?
A) They are composed of 80S subunits.
B) The small subunit contains 23S and 5S rRNA.
C) They are the sites of DNA replication.
D) Bacterial ribosomes are 70S, composed of 16S rRNA in the small subunit and 23S, 5S rRNA in the large subunit.

A

D) Bacterial ribosomes are 70S, composed of 16S rRNA in the small subunit and 23S, 5S rRNA in the large subunit.

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3
Q

What role does the 23S rRNA play in bacterial ribosomes?
A) Binds to the Shine-Dalgarno sequence.
B) Catalyzes peptide bond formation.
C) Initiates transcription.
D) Aids in ribosome assembly.

A

B) Catalyzes peptide bond formation.

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4
Q

During bacterial protein synthesis, the A (acceptor) site of the ribosome:
A) Receives tRNA carrying an amino acid.
B) Holds tRNA attached to the growing polypeptide chain.
C) Is the exit site for empty tRNA.
D) Catalyzes peptide bond formation.

A

A) Receives tRNA carrying an amino acid.

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5
Q

In bacteria, what is the main initiator tRNA used during the initiation of protein synthesis?
A) Methionine-tRNA
B) N-formylmethionine-tRNA
C) UAA codon
D) GTP-bound tRNA

A

B) N-formylmethionine-tRNA

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6
Q

Which process during protein elongation involves the transfer of the peptide chain from the P site to the A site?
A) Translocation
B) Termination
C) Transpeptidation
D) Initiation

A

C) Transpeptidation

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7
Q

The final phase of the elongation cycle in protein synthesis, translocation, requires:
A) Hydrolysis of ATP.
B) Hydrolysis of GTP.
C) Formation of peptide bonds.
D) Binding of tRNA to the Shine-Dalgarno sequence.

A

B) Hydrolysis of GTP.

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8
Q

Plasmids in bacteria:
A) Are always integrated into the bacterial chromosome.
B) Are extrachromosomal, circular DNA molecules that can replicate independently.
C) Contain peptidoglycan synthesis genes.
D) Do not contribute any advantage to bacterial cells.

A

B) Are extrachromosomal, circular DNA molecules that can replicate independently.

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9
Q

Which of the following correctly describes archaeal membranes?
A) They are composed of ester-linked phospholipids.
B) They have a glycerol diester structure.
C) They may have either a bilayer or a monolayer structure.
D) They lack any lipids.

A

C) They may have either a bilayer or a monolayer structure.

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10
Q

Archaea are distinct from bacteria because:
A) Their ribosomes are 80S.
B) They are always membrane-bound.
C) They possess a cell wall with peptidoglycan.
D) Their ribosomes have a different nucleotide sequence in rRNA and are unaffected by antibiotics targeting bacterial ribosomes.

A

D) Their ribosomes have a different nucleotide sequence in rRNA and are unaffected by antibiotics targeting bacterial ribosomes.

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11
Q

Which of the following is true about archaeal nucleoid organization?
A) It is always membrane-bound.
B) Archaeal chromosomes are linear.
C) Histones in archaea organize the chromosome into nucleosomes.
D) Supercoiling is not a feature of archaeal chromosomal organization.

A

C) Histones in archaea organize the chromosome into nucleosomes.

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12
Q

Archaeal motility structures (archaella) are powered by:
A) ATP hydrolysis.
B) Proton motive force.
C) GTP hydrolysis.
D) Flagellar rotation driven by chemical gradients.

A

A) ATP hydrolysis.

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13
Q

Which of the following components are common to both bacteria and archaea?
A) Both have ester-linked phospholipids in their membranes.
B) Both possess 70S ribosomes.
C) Both have peptidoglycan in their cell walls.
D) Both use proton motive force for motility.

A

B) Both possess 70S ribosomes.

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14
Q

Which of the following is NOT a phase involved in the elongation of the polypeptide chain during bacterial translation?
A) Aminoacyl-tRNA binding
B) Peptidyl transferase reaction
C) Transpeptidation reaction
D) Translocation

A

B) Peptidyl transferase reaction

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15
Q

During the termination of protein synthesis in bacteria, which event occurs when a stop codon is encountered?
A) Peptidyl transferase hydrolyzes the bond between the polypeptide and tRNA.
B) tRNA binds to the stop codon.
C) GTP is hydrolyzed to initiate the next elongation cycle.
D) The ribosome stalls and releases the mRNA.

A

A) Peptidyl transferase hydrolyzes the bond between the polypeptide and tRNA.

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16
Q

What is the function of release factors (RFs) during bacterial translation?
A) They bind to tRNA and help release amino acids.
B) They catalyze peptide bond formation.
C) They recognize stop codons and terminate translation.
D) They transport the ribosome to the Shine-Dalgarno sequence.

A

C) They recognize stop codons and terminate translation.

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17
Q

Plasmids are particularly important in bacterial genetics because:
A) They always contain essential genes for bacterial survival.
B) They can carry genes that confer a selective advantage, such as antibiotic resistance.
C) They only exist in archaea and eukaryotes.
D) They are linear double-stranded DNA molecules.

A

B) They can carry genes that confer a selective advantage, such as antibiotic resistance.

18
Q

Which feature of archaeal membranes differentiates them from bacterial and eukaryotic membranes?
A) They contain branched-chain hydrocarbons attached to glycerol by ether linkages.
B) Archaeal membranes have fatty acids attached to glycerol by ester linkages.
C) Archaeal membranes are always bilayers.
D) Their membranes lack any phospholipids.

A

A) They contain branched-chain hydrocarbons attached to glycerol by ether linkages.

19
Q

In comparison to bacterial cells, which of the following is unique to archaea?
A) Ester-linked membrane lipids.
B) Circular, double-stranded DNA.
C) Nucleoid region for chromosome storage.
D) Branched hydrocarbons in their membrane structure.

A

D) Branched hydrocarbons in their membrane structure.

20
Q

In the context of ribosomal function, which of the following is true for both bacteria and archaea?
A) Both have 80S ribosomes.
B) Both are susceptible to the same ribosome-targeting antibiotics.
C) Both have 70S ribosomes, but archaeal ribosomes have a distinct protein composition.
D) Both have ribosomes that are composed entirely of proteins.

A

C) Both have 70S ribosomes, but archaeal ribosomes have a distinct protein composition.

21
Q

How does the archaeal flagella (archaellum) differ from the bacterial flagella?
A) It is powered by proton motive force.
B) It is thinner and made of hollow filaments.
C) It is powered by ATP hydrolysis and moves the cell forward or backward.
D) It tumbles the cell for random movement.

A

C) It is powered by ATP hydrolysis and moves the cell forward or backward.

22
Q

The most common archaeal cell envelope structure is:
A) A peptidoglycan cell wall.
B) An outer membrane composed of lipopolysaccharides.
C) A double membrane with rigid layers of polysaccharides. D) An S-layer composed of many copies of a single protein.

A

D) An S-layer composed of many copies of a single protein.

23
Q

What is a key structural feature of archaeal S-layers?
A) They resemble a geometric pattern and can be tethered to the plasma membrane.
B) They are composed of lipids and glycolipids.
C) They are hollow structures composed of polysaccharides.
D) They are composed of peptidoglycan.

A

A) They resemble a geometric pattern and can be tethered to the plasma membrane.

24
Q

What unique characteristic of archaeal ribosomes makes them resistant to certain antibiotics?
A) They have 80S ribosomes like eukaryotes.
B) Their nucleotide sequence and protein composition differ from bacterial ribosomes.
C) Their ribosomes are located in a membrane-bound nucleus.
D) They lack RNA, which is targeted by antibiotics.

A

B) Their nucleotide sequence and protein composition differ from bacterial ribosomes.

25
Q

Which of the following is a distinguishing feature of archaeal lipids?
A) They consist of ester-linked fatty acids.
B) They are composed of branched isoprene units and linked by ether bonds.
C) They are predominantly linear hydrocarbons.
D) They lack polar head groups.

A

B) They are composed of branched isoprene units and linked by ether bonds.

26
Q

Which of the following best describes the structure of bacterial and archaeal chromosomes?
A) Linear, single-stranded DNA
B) Circular, double-stranded DNA
C) Linear, double-stranded DNA
D) Circular, single-stranded RNA

A

B) Circular, double-stranded DNA

27
Q

Which statement is true regarding the initiation of protein synthesis in bacteria?
A) N-formylmethionine-tRNA is the bacterial initiator tRNA.
B) It requires ATP hydrolysis to start.
C) Eukaryotes also use N-formylmethionine as the initiator tRNA.
D) The 50S ribosomal subunit binds directly to the Shine-Dalgarno sequence.

A

A) N-formylmethionine-tRNA is the bacterial initiator tRNA.

28
Q

During bacterial elongation, which of the following correctly describes the translocation process?
A) The ribosome moves forward by two codons.
B) Peptidyl-tRNA moves from the P site to the A site.
C) The ribosome moves down one codon, positioning the new codon in the A site.
D) A stop codon signals the end of the translocation process.

A

C) The ribosome moves down one codon, positioning the new codon in the A site.

29
Q

What is the role of GTP in bacterial protein synthesis?
A) It provides energy for the transpeptidation reaction.
B) It is required for the binding of the tRNA to the A site.
C) It catalyzes the formation of peptide bonds.
D) GTP hydrolysis provides energy for the translocation step.

A

D) GTP hydrolysis provides energy for the translocation step.

30
Q

In bacterial protein synthesis, what is the function of the Shine-Dalgarno sequence?
A) It marks the end of translation by signaling stop codons.
B) It serves as the ribosome binding site on the mRNA.
C) It stabilizes the tRNA at the P site of the ribosome.
D) It assists in the binding of elongation factors.

A

B) It serves as the ribosome binding site on the mRNA.

31
Q

What feature distinguishes archaeal membranes from bacterial membranes?
A) Archaeal membranes are made from ether-linked lipids derived from isoprene units.
B) Archaeal membranes are made of peptidoglycan layers.
C) Archaeal membranes are composed entirely of proteins.
D) Archaeal membranes do not contain polar phospholipids.

A

A) Archaeal membranes are made from ether-linked lipids derived from isoprene units.

32
Q

Which of the following is a characteristic of plasmids in bacterial cells?
A) Plasmids are always integrated into the bacterial chromosome.
B) They replicate independently of the bacterial chromosome.
C) They are composed of single-stranded RNA.
D) They contain only non-coding regions of DNA.

A

B) They replicate independently of the bacterial chromosome.

33
Q

Archaea are known for thriving in extreme environments. Which of the following is NOT typically an archaeal habitat?
A) Hypersaline environments
B) pH extremes
C) High-temperature habitats
D) Low-oxygen ocean depths

A

D) Low-oxygen ocean depths

34
Q

Which of the following features of archaeal ribosomes makes them more similar to eukaryotes than bacteria?
A) Archaeal ribosomes are 80S like eukaryotes.
B) Archaeal ribosomes are affected by the same antibiotics as eukaryotic ribosomes.
C) Archaeal ribosomes contain only rRNA, like eukaryotic ribosomes.
D) Archaeal ribosomal proteins are more similar to those in eukaryotes.

A

D) Archaeal ribosomal proteins are more similar to those in eukaryotes.

35
Q

What is the significance of archaeal S-layers?
A) They are composed of phospholipids.
B) They serve as a structural layer, providing protection and stabilization.
C) They are involved in protein synthesis.
D) They facilitate DNA replication.

A

B) They serve as a structural layer, providing protection and stabilization.

36
Q

Which of the following is an example of a cell envelope structure unique to archaea?
A) A peptidoglycan cell wall
B) A flagellar system for motility
C) A lipid monolayer membrane composed of glycerol tetraethers
D) A phospholipid bilayer membrane like in bacteria

A

C) A lipid monolayer membrane composed of glycerol tetraethers

37
Q

During bacterial translation, which event occurs at the P (peptidyl) site of the ribosome?
A) The tRNA enters carrying an amino acid.
B) The growing polypeptide chain is held by the tRNA.
C) The mRNA is translocated to the next codon.
D) The empty tRNA exits the ribosome.

A

B) The growing polypeptide chain is held by the tRNA.

38
Q

What makes archaeal ribosomes resistant to antibiotics that target bacterial ribosomes?
A) Their protein composition is different, making them immune to antibiotics targeting bacterial ribosomes.
B) They are enclosed in a nuclear membrane.
C) Archaeal ribosomes are larger than bacterial ribosomes.
D) They do not synthesize proteins in the same manner as bacteria.

A

A) Their protein composition is different, making them immune to antibiotics targeting bacterial ribosomes.

39
Q

What is a defining characteristic of archaeal S-layers?
A) They are composed of polysaccharides.
B) They form a geometric pattern or protein canopy.
C) They are involved in peptidoglycan synthesis.
D) They are absent in most archaea.

A

B) They form a geometric pattern or protein canopy.

40
Q

Which of the following processes during bacterial translation requires energy?
A) Peptide bond formation
B) Transpeptidation
C) Translocation
D) Binding of the Shine-Dalgarno sequence

A

C) Translocation

BIOL 321 (10 decks)

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