Deck 6: Molecular Biology of Bacteria

Question 1

An example of nucleotide pairing is

A) C and U.
B) G and U.
C) A and T.
D) T and U.

Answer 1

B

Question 2

There are about _ different tRNAs in bacterial cells and about in mammalian cells.

A) 60 / 100- 110
B) 100- 110 / 140
C) 200 / 200
D) 40 / 70

Answer 2

A

Question 3

In Bacteria and most Archaea, the enzyme that introduces negative supercoils into DNA is known as

A) DNA gyrase.
B) supercoiling gyrase.
C) prokaryotic gyrase.
D) prokaryotic supercoilase.

Answer 3

A

Question 4

Which of the following is an example of one codon?

A) CCGUAA
B) CATT
C) GCCATT
D) CAG

Question 5

Which of the following is NOT correct regarding DNA and RNA synthesis?

A) DNA is the template for both DNA and RNA synthesis.
B) The template strand is antiparallel to the newly synthesized strand.
C) Both processes require an RNA primer to begin.
D) The overall direction of chain growth is from the 5' to 3' end.

Question 6

Which statement is generally TRUE regarding protein synthesis?

A) The 23S rRNA plays a role in termination; the 16S rRNA plays a role in elongation.
B) The 23S rRNA plays a role in elongation; the 16S rRNA plays a role in translocation.
C) The 23S rRNA plays a role in translocation; the 16S rRNA plays a role in elongation.
D) The 23S rRNA plays a role in translocation; the 16S rRNA plays a role in initiation.

Question 7

DNA replication always proceeds from the _ of the incoming nucleotide to the _ of the previously added nucleotide.

A) 5'- hydroxyl / 3'- phosphate
B) 5'- phosphate / 3'- hydroxyl
C) 3'- hydroxyl /5'- phosphate
D) 3'- phosphate / 5'- hydroxyl

Question 8

In all cells, genes are composed of

A) chaperones.
B) proteins.
C) mRNA.
D) nucleic acids.

Question 9

Streptomycin inhibits of protein synthesis, whereas tetracycline inhibits _ of protein synthesis.

A) elongation / protein folding
B) initiation / maturation
C) initiation / elongation
D) maturation / protein folding

Question 10

The process whereby RNA specifies a DNA sequence is known as

A) reverse transcription.
B) RNA transcription.
C) the central dogma of molecular biology.
D) RNA translation.

Question 11

tRNA is released from the ribosome at the _ site.

A) E
B) A
C) P
D) R

Question 12

Most plasmids are

A) replicated in conjunction with the chromosome.
B) linear, though a few are circular.
C) found in eukaryotic cells, though a few are found in prokaryotic cells.
D) double- stranded DNA, though a few are not.

Question 13

Termination of RNA synthesis is ultimately determined by

A) CG- rich sequences followed by AT- rich sequences.
B) exhaustion of RNA polymerase activity.
C) specific nucleotide sequences on the template strand.
D) special protein factors.

Question 14

Proteins interact predominantly within which portion of a double- stranded DNA helix?

A) major groove
B) minor groove
C) supercoil
D) telomere

Question 15

Promoters are specific sequences of that are recognized by .

A) DNA / sigma factor
B) RNA / RNA polymerase
C) RNA / DNA polymerase
D) DNA / RNA polymerase

Question 16

Housekeeping genes are present in

A) chromosomes.
B) chromosomes and plasmids.
C) plasmids.
D) neither chromosomes nor plasmids.

Question 17

In all cells a gene encodes for

A) a tRNA.
B) an rRNA.
C) a protein (via mRNA).
D) all of the above.

Question 18

During DNA synthesis, the RNA primer is removed by a(n)

A) replisome.
B) Okazaki fragment.
C) DNA ligase.
D) Pol I exonuclease.

Question 19

AT- rich DNA will denature/melt

A) at a lower temperature than GC- rich DNA.
B) at a higher temperature than GC- rich DNA.
C) usually at the same temperature as GC- rich DNA, with some minor variations.
D) in accordance with the animal or plant from which it was taken.

Question 20

The functional unit of genetic information is called the

A) nucleotide.
B) protein.
C) gene.
D) chromosome.

Question 21

To fold properly or to assemble into larger complexes, many proteins require assistance from other proteins called .

Question 22

The template for RNA polymerase is _, and the RNA chain growth is the chain growth of DNA.

A) DNA / the opposite of
B) DNA / identical to
C) an independent RNA segment / the opposite of
D) an independent RNA segment / identical to

Question 23

The function of the DNA polymerase is to _.

Question 24

The artificial construction of a double- stranded nucleic acid by complementary base pairing of two single- stranded nucleic acids is known as .

Question 25

A transposable element is the general term for .

Question 26

The function of RNA polymerase is to .

Question 27

Stop codons are also called codons.

A) degeneracy
B) nonsense
C) conversion
D) release factor

Question 28

is an enzyme that adds phosphodiester bonds between nicked regions of DNA.

Question 29

The precursor of each new nucleotide in a strand of DNA is a

A) deoxynucleoside 5'- diphosphate.
B) deoxynucleoside 3'- triphosphate.
C) deoxynucleoside 5'- triphosphate.
D) deoxynucleoside 3'- diphosphate.

Question 30

DNA synthesis occurs continuously on the strand, while on the strand DNA synthesis occurs discontinuously.

Question 31

A triplet of bases on an mRNA molecule is known as a(n) .

Question 32

A DNA double helix occurs when _ .

Question 33

Transcription of chaperonins is greatly accelerated when a cell is stressed by

A) excessive heat.
B) lack of oxygen.
C) excessive osmotic pressure.
D) extremes in pH value.

Question 34

In complementary base pairing of DNA, adenine pairs with _ (or in RNA) and cytosine always pairs with _.

Question 35

A group of genes that are transcribed together is called a(n) _ , which synthesizes a(n) .

Question 36

The flow of biological information begins with

A) RNA transcription.
B) transcriptional regulation.
C) DNA replication.
D) mRNA translation.

Question 37

The sequence of three to nine nucleotides upstream of the start codon that helps bind the mRNA to the ribosome is known as the _ .

Question 38

GTP provides energy for

A) protein folding.
B) transcription.
C) translation.
D) DNA replication.

Question 39

DNA participates in protein synthesis through a(n) .

Question 40

Ciprofloxacin, nalidixic acid, and novobiocin are effective antibiotics because they inhibit the activity of

A) prokaryotic supercoilase.
B) reverse gyrase.
C) RNA topoisomerase.
D) DNA gyrase.

Question 41

When several ribosomes are simultaneously translating a single mRNA molecule, the complex is called a(n) .

Question 42

Aminoacyl- tRNA synthetase catalyzes the reaction between the appropriate amino acid and ATP to form an activated amino acid: amino acid + ATP -aminoacyl- AMP + P- P

Question 43

DNA replication is started with a(n) , which, in most cases, in vivo is a short stretch of .

Question 44

Proteins known as chaperones are found only in Bacteria, and their sequences vary from organism to organism.

Question 45

rRNA has a functional role in all stages of protein synthesis.

Question 46

The genetic code is conventionally written as rather than _, because that is the molecule with which the translation process occurs.

Question 47

If a transcription unit contains two or more genes, these genes are then _ _, giving a single RNA molecule.

Question 48

DNA replication is bidirectional in prokaryotes with circular chromosomes.

Question 49

Inverted repeats can lead to stem- loop structures in the DNA molecule.

Question 50

The universal start codon is , and it codes for _ in Bacteria.

Question 51

DNA replication involves the synthesis of an RNA primer on one strand of the DNA.

Question 52

RNA acts at both the genetic and the functional levels.

Question 53

In Bacteria, a chromosome can be distinguished from a plasmid, because by definition a chromosome is a genetic element whose genes encode for .

Question 54

Sometimes it appears that bases in tRNA loops are actually paired with bases in other tRNA loops, which is not the case because pairing occurs exclusively within a given loop.

Question 55

Each adenine- thymine base pair has _ hydrogen bonds, while each guanine- cytosine base pair has _ _ hydrogen bonds.

Question 56

The genetic material in a virus is technically called a plasmid.

Question 57

The structure and function of a protein are determined by its sequence.

Question 58

In nature, the predominant form of DNA is supercoiled in a negative direction.

Question 59

The twenty- first and twenty- second genetically encoded amino acids are _ and
.

Question 60

Bacterial proteins that kill closely related strains or species are collectively called , and the genes that encode for them are usually present on _.

Question 61

Throughout the living world, the genetic code is generally universal; however, there are some slight variations.

Question 62

Explain how Escherichia coli can grow with a doubling time of 20 minutes when chromosome replication takes 40 minutes.

Question 63

Explain the A site, the P site, and the E site in terms of the ribosomal subunits.

Question 64

Explain the concept of semiconservative replication.

Question 65

Discuss the initiation of DNA synthesis in Bacteria using the terms origin of replication, replication fork, and theta structures.

Question 66

Explain the differences between viruses and plasmids.

Question 67

Most prokaryotic genomes are double- stranded circular DNA.

Question 68

Explain why a cell needs both type I and type II topoisomerases.

Question 69

Speculate on why it may be problematic to clone a gene from a prokaryote into a eukaryote.

Question 70

Name and give one characteristic feature of each of the three major types of transposable elements.

Question 71

Explain the role of the signal recognition particle (SRP) in protein secretion compared to SecA.

Question 72

How can an open reading frame (ORF) be used to determine the location of a protein- encoding gene?

Question 73

A polymerase chain reaction (PCR) amplifies a specific DNA sequence up to a billion- fold.

Question 74

One high- energy phosphate bond is required for the activation of an aminoacyl- tRNA.

Question 75

Describe protein synthesis in terms of initiation, elongation, and termination/release.

Question 76

Explain the process of RNA transcription using the terms upstream, Pribnow box, and consensus sequence.

Question 77

Explain why DNA, RNA, and proteins are often called informational macromolecules.

Question 78

Explain the difference between transcription and translation.

Question 79

Define genome in terms of the various DNA components of the cell or virus.

Question 80

Explain the role of sigma factors in RNA synthesis.