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Microbiology > Exam 3 - Microbial Genetics > Flashcards

Exam 3 - Microbial Genetics Flashcards

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
Hydrogen bonding
attraction between opposite charges (stabilizes complementary base pairs)
26
Complementary base pairs+ how many H-bonds
Adenine to Thymine A to T = Two hydrogen bonds Cytosine to Guanine C to G = Three hydrogen bonds
27
Phosphodiester bonds
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.**
28
Sugar-phosphate backbone
alternating sugar-phosphate structure composing the framework of a nucleic acid strand;**phosphodiester bonds**
29
Vertical Gene Transfer
transmission of genetic information from mother to daughter cells; occurs through DNA replication
30
Genetics definition
study of function and transfer of genes
31
Genomics
study of the sequence of DNA replication
32
Chromosome
a long DNA molecule with part or all of the genetic material of an organism.
33
Transposable elements
segments of DNA that move from one place in the genome to another
34
Organellar genomes | seperate DNA outside of nucleus ## Footnote what organelles?
**separate** DNA within mitochondria and/or chloroplasts | seperate outside of nucleus
35
Viruses
encoded either by RNA or DNA; directs replication of virus by a host cell
36
Helicase
enzyme that unzips an organism's genetic material
37
Promoter
Region where RNA polymerase binds to DNA (landing pad)
38
UTR
untranslated region
39
replication begins here; ~250 nucleotides localized separation of strands replication proceeds bidirectionally from origin
origin of replication
40
DNA is synthesized ____ nucleotide at a time as a _________
one; subunit
41
DNA polymerase can only add nucleotides to:
free hydroxyl at the 3' end
42
DNA polymerase replicates ONLY in what direction?
5' to 3'
43
What direction do enzymes read DNA templates?
3' to 5'
44
What direction will two new strands of DNA grow?
Antiparallel; opposite directions with one leading and one lagging
45
synthesized continuously as DNA polymerase moves towards replication fork
Leading strand
46
Lagging strand
synthesized discontinuously as DNA polymerase moves away from the replication fork
47
DNA ligase
joins together the gaps in sugar-phosphate backbone
48
Linear chromosomes require ________ origins of replication
multiple
49
Why is replication of a full chromosome problematic?
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
Telomere
region of repetitive DNA sequences at the end of a chromosome
51
T/F DNA polymerase can both add and remove bases
True
52
Exonuclease
enzymes that work by cleaving nucleotides one at a time from the end (exo) of a polynucleotide chain
53
Gene expression involves ___________ and ___________
transcription and translation
54
Transcription
Process of synthesizing mRNA from DNA template
55
Translation
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
mRNA
messenger ribonucleic acid; carries coded information from DNA to the ribosome (site of protein synthesis)
57
RNA polymerase sythesizes what from a portion of unwound DNA during transcription?
a complementary strand
58
the one strand of DNA acting as the template for mRNA during transcription
Sense strand | (opposed to nonsense strand)
59
Promoter
region of DNA where RNA polymerase binds
60
Terminator
region where RNA polymerase terminates, and released along with the new mRNA strand
61
Translation can begin before transcription has finished in _________, but not in __________
Bacteria, Eukarya
62
Eukaryote transcription and translation regions:
Transcription occurs in the nucleus Translation occurs in the cytoplasm
63
In human genome, how much % is protein encoding?
3%
64
In yeast, how much % is protein encoding
70%
65
In Bacteria, how much % is protein encoding?
>90%
66
Introns
Eukaryotic non-coding regions
67
Exons
Interspersed among coding regions
68
Splicing
process that removes introns before gene translation
69
Ribosomal RNA (rRNA) func.
forms part of the ribosomal machinery used in protein synthesis | (builds ribosomes)
70
Transfer RNA (tRNA)func.
recognizes specific sequences of mRNA and transports the required amino acids to form a polypeptide chain
71
Codons
**(language of mRNA)** groups of three nucleotides situated next to each other on DNA; written in terms of their base sequences in mRNA
72
Site of translation
Ribosome
73
tRNA brings the appropriate amino acids to the site of translation in response to what?
Codons
74
Anticodon
complementary sequence to the codon
75
Start codon for all proteins
AUG - methionine
76
Translation Initiation
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
Translation Elongation
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
Translation Termination
Ribosomes come to a stop or nonsense codon >>Ribosomes seperate >>new polypeptide chain released
79
Bacterial Gene Regulation
min/maxing cell material from limited energy
80
Two general mechanisms of Bacterial Gene Regulation
Allosteric inhibition of enzymes Controlling synthesis of enzymes
81
Regulation Enzyme classifications
Constitutive Inducible Repressible
82
ezymes that are constantly synthesized | ex>>enzymes of glycolysis
Constitutive enzymes
83
not regularly produced turned on in certain conditions | >>B-galactosidase
Inducible enzmyes
84
Repressible enzymes are: (3) | synthesization frequency off or on in certain conditions biosythesis?
Routinely synthesized turned off in certain conditions generally involved in biosynthesis
85
T or F Mechanisms to prevent or facilitate transcription must be impossible to reverse
F
86
DNA Binding proteins
can either act as a repressor, which blocks transcription, or an activator, which facilitates transcription
87
DNA binded repressors
regulatory protein that blocks transcription by binding to a DNA sequence called an operator regulation with a repressor = negative control
88
regulatory protein that facilitates transcription regulation with activator = positive control
DNA binded activators
89
Operon
set of genes: operator/promoter/structural genes
90
The two regions of Operon
control and structural
91
Operon Control Region
Contains operator and promoter >>controls transcription >>operator acts as "on-off" switch
92
Operon Structural Region
region contains genes being transcribed
93
CAP
Catabolic activator protein
94
Many organisms adapt to changing environments by altering the level of ______ ____________
gene expression
95
Signal transduction
process that transmits information from external environment to inside the cell >>two-component regulatory systems >>Quorum sensing
96
Two-component regulatory systems
relies on sensor and response regulator proteins
97
Sensor regulator proteins
recognize changes in environment
98
response regulator proteins
activate or repress gene expression
99
Quorum sensing
sense of population density in organisms (chemical excrements)

Microbiology (15 decks)

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