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Microbiology > Exam 3 - Microbial Genetics > Flashcards

Exam 3 - Microbial Genetics Flashcards

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1
Q

If a DNA strand contains the sequence 5ʹ-ATTCCGGATCGA-3ʹ, which of the following is the sequence of the complementary strand of DNA?

5ʹ-TCGATCCGGAAT-3ʹ
3ʹ-TAACCGGTACGT-5ʹ
5ʹ-ATTCCGGATCGA-3ʹ
5ʹ-TAAGGCCTAGCT-3ʹ

A

5ʹ-TCGATCCGGAAT-3ʹ

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2
Q

More primers are used in lagging strand synthesis than in leading strand synthesis. T or F?

A

True

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3
Q

Which of the following statements about base pairing in DNA is incorrect?

Purines always base pairs with pyrimidines.
Base pairing occurs at the interior of the double helix.
Adenine binds to guanine.
Base pairs are stabilized by hydrogen bonds.

A

Adenine binds to guanine.

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4
Q

Which of the following enzymes involved in DNA replication is unique to eukaryotes?

helicase
ligase
telomerase
DNA polymerase

A

telomerase

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5
Q

Which of the following is not found within DNA?

thymine
phosphodiester bonds
amino acids
complementary base pairing

A

amino acids

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6
Q

The noncoding, repetitive sequences at the end of eukaryotic chromosomes are called which of the following?

forks
lagging strands
bubbles
telomeres

A

telomeres

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7
Q

During bacterial DNA replication, which of the following holds open the replication bubble?

single-strand binding proteins
helicases
primers
DNA polymerases

A

single-strand binding proteins

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8
Q

One strand of DNA runs from 5′ to 3′ and the opposing strand runs 3′ to 5′, meaning that the strands are oriented in which way?

conservative
antiparallel
helical
semiconservative

A

antiparallel

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9
Q

Which of the following correctly explains why DNA replication is described as semiconservative?

Each daughter strand contains one old strand and one new strand.
The nucleotides used in replication contain old and new components.
The nucleotides used in replication are recycled multiple times.
Each daughter strand contains two new strands.

A

Each daughter strand contains one old strand and one new strand.

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10
Q

A DNA nucleotide contains which of the following?

a ribose sugar and a nitrogenous base
a ribose sugar, a phosphate, and a nitrogenous base
a deoxyribose sugar, a phosphate, and a nitrogenous base
a deoxyribose sugar and a nitrogenous base

A

a deoxyribose sugar, a phosphate, and a nitrogenous base

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11
Q

Which of the following is a name for nitrogenous bases with a double-ring structure?

nucleotides
purines
pyrimidines
nucleosides

A

purines

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12
Q

Telomeres found in which of the following?

animal cells only, not in unicellular organisms
fungal, protist, plant, and animal chromosomes microbes only, including all domains
all microbes

A

fungal, protist, plant, and animal chromosomes

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13
Q

Which of the following best describes the direction in which lagging strands are added?

in the 3′ to 5′ or 5′ to 3′ direction
as 5′ to 3′ Okazaki fragments in an overall 5′ to 3′ direction only
in variable directions depending on the species
as 5′ to 3′ Okazaki fragments in an overall 3′ to 5′ direction only

A

as 5′ to 3′ Okazaki fragments in an overall 3′ to 5′ direction only

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14
Q

During DNA replication, the lagging strand is formed from which of the following?

helicases
single strand binding proteins
leading strands
Okazaki fragments

A

Okazaki fragments

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15
Q

DNA polymerase adds DNA nucleotides in which of the following direction(s)?

in the 3′ to 5′ direction and in 5′ to 3′ direction
in the 3′ to 5′ direction only
in the 5′ to 3′ direction on one strand and in the 3′ to 5′ direction on the complementary strand
in the 5′ to 3′ direction only

A

in the 5′ to 3′ direction only

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16
Q

Which strand (leading or lagging) is going to require more attention from DNA ligase?

A

Lagging, due to the Okazaki fragment gaps requiring to be joined back together.

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17
Q

Nucleic acids def.

A

fourth class of macromolecules, composed of nucleotides

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18
Q

Nucleotides

A

monomers that make up nucleic acids; contains pentose sugar, phosphate group, and a nitrogenous base.

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19
Q

Base sequence

A

the order in which nucleotides appear

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20
Q

Deoxyribonucleic Acid (DNA)

A

responsible for carrying and retaining the hereditary information in a cell (no structural role in cells)

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21
Q

Deoxyribonucleotides

A

nucleotides that compose DNA = 5-Carbon sugar called deoxyribose, a phosphate group and a nitrogenous base

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22
Q

Nitrogenous base

A

a nitrogen ring structure that is responsible for complementary base pairing between nucleic acid strands

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23
Q

Purines (Ex and def.)

A

Adenine (A), Guanine (G) = Double-ring structure with a 6-Carbon ring fused to a 5-Carbon ring

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24
Q

Pyrimidines (Ex and structure)

A

Cytosine (C), Thymine (T) = only one 6-Carbon ring structure

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25
Q

Hydrogen bonding

A

attraction between opposite charges
(stabilizes complementary base pairs)

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26
Q

Complementary base pairs+ how many H-bonds

A

Adenine to Thymine A to T = Two hydrogen bonds
Cytosine to Guanine C to G = Three hydrogen bonds

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27
Q

Phosphodiester bonds

A

linkages by the phosphate group attached to a 5’ carbon of the sugar of one nucleotide bonds to the hydroxyl group of the 3’ carbon of the sugar of the next nucleotide; forming the sugar-phosphate backbone.

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28
Q

Sugar-phosphate backbone

A

alternating sugar-phosphate structure composing the framework of a nucleic acid strand;phosphodiester bonds

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29
Q

Vertical Gene Transfer

A

transmission of genetic information from mother to daughter cells; occurs through DNA replication

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30
Q

Genetics definition

A

study of function and transfer of genes

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31
Q

Genomics

A

study of the sequence of DNA replication

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32
Q

Chromosome

A

a long DNA molecule with part or all of the genetic material of an organism.

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33
Q

Transposable elements

A

segments of DNA that move from one place in the genome to another

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34
Q

Organellar genomes

seperate DNA outside of nucleus

what organelles?

A

separate DNA within mitochondria and/or chloroplasts

seperate outside of nucleus

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35
Q

Viruses

A

encoded either by RNA or DNA; directs replication of virus by a host cell

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36
Q

Helicase

A

enzyme that unzips an organism’s genetic material

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37
Q

Promoter

A

Region where RNA polymerase binds to DNA (landing pad)

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38
Q

UTR

A

untranslated region

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39
Q

replication begins here; ~250 nucleotides
localized separation of strands
replication proceeds bidirectionally from origin

A

origin of replication

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40
Q

DNA is synthesized ____ nucleotide at a time as a _________

A

one; subunit

41
Q

DNA polymerase can only add nucleotides to:

A

free hydroxyl at the 3’ end

42
Q

DNA polymerase replicates ONLY in what direction?

A

5’ to 3’

43
Q

What direction do enzymes read DNA templates?

A

3’ to 5’

44
Q

What direction will two new strands of DNA grow?

A

Antiparallel; opposite directions with one leading and one lagging

45
Q

synthesized continuously as DNA polymerase moves towards replication fork

A

Leading strand

46
Q

Lagging strand

A

synthesized discontinuously as DNA polymerase moves away from the replication fork

47
Q

DNA ligase

A

joins together the gaps in sugar-phosphate backbone

48
Q

Linear chromosomes require ________ origins of replication

A

multiple

49
Q

Why is replication of a full chromosome problematic?

A

DNA polymerase only binds to 3’ OH
DNA polymerase can’t replace with DNA once primer is removed
Telomeres shortened after every replication; cell division stops once telomere is too short

50
Q

Telomere

A

region of repetitive DNA sequences at the end of a chromosome

51
Q

T/F
DNA polymerase can both add and remove bases

A

True

52
Q

Exonuclease

A

enzymes that work by cleaving nucleotides one at a time from the end (exo) of a polynucleotide chain

53
Q

Gene expression involves ___________ and ___________

A

transcription and translation

54
Q

Transcription

A

Process of synthesizing mRNA from DNA template

55
Q

Translation

A

a process in living cells in which proteins are produced using RNA molecules as templates

opposed to transcription, where DNA molecules are used as templates

56
Q

mRNA

A

messenger ribonucleic acid; carries coded information from DNA to the ribosome (site of protein synthesis)

57
Q

RNA polymerase sythesizes what from a portion of unwound DNA during transcription?

A

a complementary strand

58
Q

the one strand of DNA acting as the template for mRNA during transcription

A

Sense strand

(opposed to nonsense strand)

59
Q

Promoter

A

region of DNA where RNA polymerase binds

60
Q

Terminator

A

region where RNA polymerase terminates, and released along with the new mRNA strand

61
Q

Translation can begin before transcription has finished in _________, but not in __________

A

Bacteria, Eukarya

62
Q

Eukaryote transcription and translation regions:

A

Transcription occurs in the nucleus
Translation occurs in the cytoplasm

63
Q

In human genome, how much % is protein encoding?

A

3%

64
Q

In yeast, how much % is protein encoding

A

70%

65
Q

In Bacteria, how much % is protein encoding?

A

> 90%

66
Q

Introns

A

Eukaryotic non-coding regions

67
Q

Exons

A

Interspersed among coding regions

68
Q

Splicing

A

process that removes introns before gene translation

69
Q

Ribosomal RNA (rRNA) func.

A

forms part of the ribosomal machinery used in protein synthesis

(builds ribosomes)

70
Q

Transfer RNA (tRNA)func.

A

recognizes specific sequences of mRNA and transports the required amino acids to form a polypeptide chain

71
Q

Codons

A

(language of mRNA)
groups of three nucleotides situated next to each other on DNA; written in terms of their base sequences in mRNA

72
Q

Site of translation

A

Ribosome

73
Q

tRNA brings the appropriate amino acids to the site of translation in response to what?

A

Codons

74
Q

Anticodon

A

complementary sequence to the codon

75
Q

Start codon for all proteins

A

AUG - methionine

76
Q

Translation Initiation

A

30s/50s ribosomal subunits join around the mRNA
then direct binding of tRNA to the correct codon on mRNA; first binding at P site, second bonding at A site = amino acids from first tRNA and second tRNA form peptide bond

77
Q

Translation Elongation

A

tRNA leaves P site once peptide bond is formed
Ribosome moves a distance of one codon
A.Acid in A site moves to P site
new tRNA fills now empty A site
Ribosome continues down strand of mRNA

78
Q

Translation Termination

A

Ribosomes come to a stop or nonsense codon
»Ribosomes seperate
»new polypeptide chain released

79
Q

Bacterial Gene Regulation

A

min/maxing cell material from limited energy

80
Q

Two general mechanisms of Bacterial Gene Regulation

A

Allosteric inhibition of enzymes
Controlling synthesis of enzymes

81
Q

Regulation Enzyme classifications

A

Constitutive
Inducible
Repressible

82
Q

ezymes that are constantly synthesized

ex»enzymes of glycolysis

A

Constitutive enzymes

83
Q

not regularly produced
turned on in certain conditions

|&raquo_space;B-galactosidase

A

Inducible enzmyes

84
Q

Repressible enzymes are: (3)

synthesization frequency
off or on in certain conditions
biosythesis?

A

Routinely synthesized
turned off in certain conditions
generally involved in biosynthesis

85
Q

T or F
Mechanisms to prevent or facilitate transcription must be impossible to reverse

A

F

86
Q

DNA Binding proteins

A

can either act as a repressor, which blocks transcription, or an activator, which facilitates transcription

87
Q

DNA binded repressors

A

regulatory protein that blocks transcription by binding to a DNA sequence called an operator
regulation with a repressor = negative control

88
Q

regulatory protein that facilitates transcription
regulation with activator = positive control

A

DNA binded activators

89
Q

Operon

A

set of genes: operator/promoter/structural genes

90
Q

The two regions of Operon

A

control and structural

91
Q

Operon Control Region

A

Contains operator and promoter
»controls transcription
»operator acts as “on-off” switch

92
Q

Operon Structural Region

A

region contains genes being transcribed

93
Q

CAP

A

Catabolic activator protein

94
Q

Many organisms adapt to changing environments by altering the level of ______ ____________

A

gene expression

95
Q

Signal transduction

A

process that transmits information from external environment to inside the cell
»two-component regulatory systems
»Quorum sensing

96
Q

Two-component regulatory systems

A

relies on sensor and response regulator proteins

97
Q

Sensor regulator proteins

A

recognize changes in environment

98
Q

response regulator proteins

A

activate or repress gene expression

99
Q

Quorum sensing

A

sense of population density in organisms (chemical excrements)

Microbiology (15 decks)

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