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Microbiology > Microbiology Exam III > Flashcards

Microbiology Exam III Flashcards

1
Q

Key points of genetics.

A

The science of heredity; the central dogma of molecular biology; mutations; gene expression controlled by operons.

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2
Q

What is the typical chain of events described by the central dogma?

A

DNA -> mRNA -> Protein -> Function

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3
Q

How do mutations alter a genome?

A

Mutated DNA -> Mutated mRNA -> Altered protein -> Altered function

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4
Q

What are 3 things that the alteration of bacterial genes and gene expression can cause?

A
  1. Cause of disease
  2. Prevent disease treatment
  3. Manipulated for human benefit
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5
Q

Define Genetics.

A

The study of genes,
how they carry information,
how information is expressed,
and how genes are replicated.

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6
Q

Define Chromosomes.

A

Structures
containing DNA that
physically carry hereditary
information; the
chromosomes contain genes.

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7
Q

Define Genes.

A

Segments of DNA
that encode functional
products, usually proteins.

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8
Q

Define Genome.

A

All the genetic
information in a cell.

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9
Q

What is the Genetic code?

A

A set of rules that determine how a
the nucleotide sequence is converted to an amino acid a sequence of a protein.

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10
Q

Central Dogma

A

DNA -> RNA -> Protein

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11
Q

Define Genotype.

A

The genetic makeup of an organism,

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12
Q

Define Phenotype.

A

The outward expression of a gene.

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13
Q

Bacteria usually have a ________ circular chromosome made of DNA and associated proteins.

A

Singular

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14
Q

Define Vertical gene transfer.

A

The flow of genetic information from
one generation to the next.

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15
Q

Define Horizontal gene transfer.

A

The flow of genetic information
within the same generation.

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16
Q

DNA is the __________ for a cell’s proteins, including enzymes.

A

Blueprint

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17
Q

What is obtained either from another cell in the same generation or from the parent cell during cell division?

A

DNA

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18
Q

DNA can be expressed within a cell or transferred to another cell through __________ or ___________.

A

Recombination and Replication

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19
Q

Explain DNA expression.

A

Genetic information is used
within a cell to produce the
proteins needed for the cell
to function.
*Cell metabolizes and grows

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20
Q

Explain DNA recombination.

A

Genetic information can be
transferred horizontally between
cells of the same generation.
*Recombinant cell

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21
Q

Explain DNA replication.

A

Genetic information can be
transferred vertically to the
next generation of cells.
*Offspring cells

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22
Q

What does DNA form?

A

A double-helix

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23
Q

What does the backbone of DNA consist of?

A

Deoxyribose-phosphate

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24
Q

What are the two stands of nucleotides held together by?

A

Hydrogen bonds between A-T and C-G

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25
Q

DNA strands are ____________.

A

Antiparallel

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26
Q

What forms the genetic instructions of the organism?

A

The order of the nitrogen-containing bases.

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27
Q

Explain the antiparallel direction of DNA.

A

The sugar-phosphate backbone of one strand is upside down relative to the backbone of the other stand.

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28
Q

What serves as a template for the production of the second stand of DNA?

A

The first DNA strand

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29
Q

What two enzymes relax the DNA strands?

A

Topoisomerase and
Gyrase

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30
Q

What enzyme separates the strands?

A

Helicase

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31
Q

What is created at the separation of the enzymes?

A

A replication fork

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32
Q

One “parental” double-
a stranded DNA molecule is
__________ to two identical
offspring molecules.

A

Converted

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33
Q

What nucleotides/elements make up DNA?

A

Nucleotides
A- Adenine
T- Thymine
C- Cytosine
G- Guanine

Elements
Deoxyribose sugar
Phosphate

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34
Q

What happens to the double helix of the parental DNA?

A

It separates as weak hydrogen bonds between the nucleotides on opposite strands break in response to the action of replication enzymes.

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35
Q

During replication, what do hydrogen bonds form between?

A

They form between new complementary nucleotides and each parental template strand to form new base pairs.

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36
Q

During replication, what do enzymes catalyze the formation of?

A

They catalyze the formation of sugar-phosphate bonds between sequential nucleotides on each resulting daughter strand.

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37
Q

During replication, what does DNA polymerase do?

A

It adds nucleotides to the growing DNA strand.

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38
Q

How does DNA polymerase add nucleotides to the DNA strand?

A
  1. In the 5’ -> 3’ direction.
  2. Leading strand is synthesized continuously.
  3. Lagging strand is synthesized discontinuously, creating
    Okazaki fragments.
  4. DNA polymerase removes RNA primers; Okazaki
    fragments are joined by the DNA polymerase and DNA
    ligase.
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39
Q

Purpose of DNA Ligase.

A

Makes covalent bonds join DNA strands; Okazaki fragments, and new segments in excision repair.

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40
Q

Purpose of Endonucleases.

A

Cut DNA backbone in a strand of DNA; facilitate repair and insertions.

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41
Q

Purpose of Exonucleases.

A

Cut DNA from an exposed end of DNA; facilitate repair.

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42
Q

Purpose of Methylase.

A

Adds methyl group to selected bases in newly made DNA.

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43
Q

Purpose of Photolyase.

A

Uses visible light energy to separate UV-induced pyrimidine dimers.

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44
Q

Purpose of Primase.

A

An RNA polymerase that makes RNA primers from a DNA template.

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45
Q

Purpose of Ribozyme.

A

RNA enzyme that removes introns and splices exons together.

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46
Q

Purpose of snRNP.

A

RNA protein complex that removes introns and splices exons together.

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47
Q

Purpose of Transposase.

A

Cuts DNA backbone, leaving single-stranded “sticky-ends”.

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48
Q

Summary of the events at the replication fork.

A
  1. Enzymes unwind the parental double
    helix.
  2. Proteins stabilize the unwound parental DNA.
  3. The leading strand is synthesized continuously by DNA polymerase.
  4. The lagging strand is synthesized discontinuously. Primase, an RNA polymerase, synthesizes a short RNA primer, which is then extended by
    DNA polymerase.
  5. DNA polymerase digests RNA primer and replaces it with DNA.
  6. DNA ligase joins the discontinuous fragments of the lagging strand.
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49
Q

During replication, how is energy supplied?

A

By nucleotides

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50
Q

How do the nucleotides provide energy?

A

Hydrolysis of two phosphate groups on ATP provides energy.

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51
Q

What happens when a nucleotide triphosphate bonds to the sugar?

A

It loses two phosphates.

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52
Q

Most bacterial DNA replication
is ______________.

A

Bidirectional

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53
Q

Each offspring cell receives
_____ copy of the DNA
molecule.

A

One

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54
Q

Replication is highly accurate
due to the proofreading
the capability of __________.

A

DNA polymerase

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55
Q

Characteristics of RNA.

A
  1. Single-stranded nucleotide
  2. 5-carbon ribose sugar
  3. Contains Uracil (U) instead of Thymine (T)
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56
Q

What is Ribosomal RNA (rRNA)?

A

Integral part of
ribosomes

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57
Q

What is Transfer RNA (tRNA)?

A

Transports amino acids
during protein synthesis.

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58
Q

What is Messenger RNA (mRNA)?

A

Carries coded
information from DNA to ribosomes.

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59
Q

Synthesis of a complementary mRNA strand from a __________.

A

DNA template

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60
Q

When does transcription begin?

A

RNA polymerase binds to the promoter sequence on DNA.

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61
Q

After RNA polymerase beings to the promoter sequence, what happens?

A

Transcription proceeds in the 5’ -> 3’ direction; only one of the two DNA strands is transcribed.

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62
Q

When does transcription stop?

A

When it reaches the
terminator sequence on DNA.

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63
Q

Explain the Transcription process.

A
  1. RNA polymerase binds to the promoter, and DNA unwinds at the beginning of
    a gene.
  2. RNA is synthesized by complementary
    base pairing of free nucleotides with the
    nucleotide bases on the template strand
    of DNA.
  3. The site of synthesis moves along DNA;
    DNA that has been transcribed rewinds.
  4. Transcription reaches the terminator.
  5. RNA and RNA polymerase are
    released, and the DNA helix re-forms.
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64
Q

What is mRNA translated into?

A

The “language” of proteins.

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65
Q

What are Codons?

A

Groups of three mRNA nucleotides
that code for a particular amino acid.

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66
Q

How many sense codons encode the 20 amino acids?

A

61

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67
Q

The genetic code involves ___________, meaning each amino acid is coded by several codons.

A

Degeneracy

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68
Q

Translation of UUU and UUC.

A

Phe

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69
Q

Translation of UUA and UUG.

A

Leu

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70
Q

Translation of UCU, UCC, UCA, and UCG.

A

Ser

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71
Q

Translation of UAU and UAC.

A

Tyr

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72
Q

Translation of UAA and UAG.

A

Stop

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73
Q

Translation of UGU and UGC.

A

Cys

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74
Q

Translation of UGA.

A

Stop

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75
Q

Translation of UGG.

A

Trp

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76
Q

Translation of CUU, CUC, CUA, and CUG.

A

Leu

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77
Q

Translation of CCU, CCC, CCA, CCG.

A

Pro

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78
Q

Translation of CAU and CAC.

A

His

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79
Q

Translation of CAA and CAG.

A

Gin

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80
Q

Translation of CGU, CGC, CGA, and CGG.

A

Arg

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81
Q

Translation of AUU, AUC, and AUA.

A

Lle

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82
Q

Translation of AUG.

A

Met/Start

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83
Q

Translation of ACU, ACC, ACA, and ACG.

A

Thr

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84
Q

Translation of AAU and AAC.

A

Asn

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85
Q

Translation of AAA and AAG.

A

Lys

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86
Q

Translation of AGU and AGC.

A

Ser

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87
Q

Translation of AGA and AGG.

A

Arg

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88
Q

Translation of GUU, GUC, GUA, and GUG.

A

Val

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89
Q

Translation of GCU, GCC, GCA, and GCG.

A

Ala

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90
Q

Translation of GAU and GAC.

A

Asp

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91
Q

Translation of GAA and GAG.

A

Glu

92
Q

Translation of GGU, GGC, GGA, and GGG.

A

Gly

93
Q

What codon does the translation of mRNA begin with?

A

AUG

94
Q

What codon does the translation of mRNA stop with?

A

UAA, UAG, and UGA

95
Q

Codons of mRNA are “read” __________.

A

Sequentially

96
Q

____________ transport the required amino acids to the ribosome.

A

tRNA molecules

97
Q

tRNA molecules also have an _______ that base-pairs with the codon.

A

Anticodon

98
Q

What are amino acids joined by?

A

Peptide bonds

99
Q

The process of Translation.

A
  1. Components needed to begin
    translation come together.
  2. On the assembled ribosome, a tRNA carrying the first amino acid is paired with the start codon on the mRNA. The place where this first tRNA sits is called the P site. A tRNA carrying the second amino acid approaches.
  3. The second codon of the mRNA pairs with a tRNA carrying the second amino acid at the A site. The first amino acid joins to the second by a peptide bond. This attaches the polypeptide to the tRNA in the P site.
  4. The ribosome moves along the mRNA until the second tRNA is in the P site. The next codon to be translated is brought into the A site. The first tRNA now occupies the E site.
  5. The second amino acid joins with the third with another peptide bond and the first tRNA is released from the E site.
  6. The ribosome continues to move along the mRNA, and new amino acids are added to the polypeptide.
  7. When the ribosome reaches a stop
    codon, the polypeptide is released.
  8. Finally, the last tRNA is released, and the ribosome comes apart. The released polypeptide forms a new protein.
100
Q

In __________, translation can begin before transcription is complete.

A

Bacteria

101
Q

In __________, transcription occurs in the nucleus, whereas translation occurs in the cytoplasm.

A

Eukaryotes

102
Q

What are exons?

A

Regions of DNA that code for proteins.

103
Q

What are introns?

A

Regions of DNA that do not code for
proteins.

104
Q

_________________ remove introns and splice exons together.

A

Small nuclear ribonucleoproteins (snRNPs)

105
Q

RNA processing in eukaryotic cells

A
  1. In the nucleus, a gene composed of exons and introns is transcribed to RNA by RNA polymerase.
  2. Processing involves snRNPs in the nucleus to remove the intron-derived RNA and splice together the exon-derived RNA into mRNA.
  3. After further modification, the mature mRNA travels to the cytoplasm, where it directs protein synthesis.
106
Q

What is the Promoter?

A

Segment of DNA where RNA polymerase initiates transcription of structural genes.

107
Q

What is the Operator?

A

Segment of DNA that controls transcription of structural genes.

108
Q

What is the Operon?

A

Set of operator and promoter sites and the structural genes they control.

109
Q

What is the structure of the operon?

A

The operon consists of the promoter (P)
and operator (O) sites and structural genes that code for the protein. The operon is regulated by the product of the regulatory gene (I).

110
Q

In an ______________, structural genes are not transcribed unless an
inducer is present.

A

Inducible operon

111
Q

In the absence of _______, the repressor binds to the operator, preventing transcription.

A

Lactose

112
Q

The repressor protein binds with the
operator, preventing transcription from the operon. When does this happen?

A

Repressor active, operon off

113
Q

In the presence of lactose, _______ (inducer) binds to the repressor;
the repressor cannot bind to the operator and transcription occurs.

A

Lactose

114
Q

When the inducer allolactose binds
to the repressor protein, the inactivated repressor can no longer block
transcription. The structural genes are transcribed, ultimately resulting
in the production of the enzymes needed for lactose catabolism. When does this happen?

A

Repressor inactive, operon on

115
Q

In _________________, structural genes are transcribed until they are turned off.

A

Repressible operons

116
Q

Excess tryptophan is a _________ that binds and activates the repressor to bind to the operator, stopping tryptophan synthesis.

A

Corepressor

117
Q

Repressor inactive, operon on. The
the repressor is inactive, and transcription
and translation proceeds, leading to the
synthesis of tryptophan.

A

Repressor inactive, operon on.

118
Q

When the corepressor tryptophan binds to the repressor protein, and the activated repressor binds with the operator, preventing transcription from the operon.

A

Repressor active, operon off.

119
Q

______________ inhibits cells from using carbon sources other than glucose.

A

Catabolite repression

120
Q

______________ builds up in a cell when glucose is not available.

A

Cyclic AMP (cAMP)

121
Q

cAMP binds to the ____________, initiating transcription and allowing the cell to use lactose.

A

Lac promoter

122
Q

__________________ base pair
with mRNA to make it double-stranded.

A

microRNAs (miRNAs)

123
Q

__________________ is enzymatically
destroyed, preventing the production of a protein.

A

Double-stranded RNA

124
Q

Define Mutation.

A

A permanent change in the base
sequence of DNA.

125
Q

Mutations can be what 3 things?

A
  1. Neutral
  2. Beneficial
  3. Harmful
126
Q

What are Mutagens?

A

Agents that cause mutations.

127
Q

When do Spontaneous mutations occur?

A

In the absence of a mutagen.

128
Q

What is the Spontaneous mutation rate?

A

1 in 10^9 replicated base pairs or 1 in 10^6 replicated genes.

129
Q

Mutagens ________ the mutation rate to 10^–5 or 10^–3 per replicated gene.

A

Increase

130
Q

Explain the Base substitution (point mutation).

A

Change in one base in DNA

131
Q

Explain the Missense mutation.

A

Results in a change in amino acid.

132
Q

Explain the Nonsense mutation.

A

Results in a nonsense (stop) codon.

133
Q

Explain the Frameshift mutation.

A

Results in and insertion or deletion of one or more nucleotide pairs.
* Shifts the translational “reading frame”

134
Q

What detects mutant cells because they grow or appear different than unmutated cells?

A

Positive (direct) selection

135
Q

What detects mutant cells that cannot grow or perform a certain function?

A

Negative (indirect) selection

136
Q

Define Autotroph.

A

A mutant that has a nutritional
requirement absent in the parent (use of replica plating).

137
Q

Replica plating

A
  1. Sterile velvet is pressed on the grown
    colonies on the master plate.
  2. Cells from each colony are transferred from the velvet to new plates.
  3. Plates are incubated.
  4. Growth on plates is compared. A colony that grows on the medium with histidine but could not grow on the medium without
    histidine is auxotrophic (histidine-requiring mutant).
138
Q

Explain Genetic recombination.

A

Exchange of genes
between two DNA molecules; creates genetic diversity.

139
Q

Explain Crossing over.

A

Two chromosomes break and
rejoin, resulting in the insertion of foreign DNA into the chromosome.

140
Q

Define Transformation.

A

Genes transferred from one
bacterium to another as “naked” DNA.

141
Q

What experiment is an example of transformation?

A

Griffith’s experiment (mice)

142
Q

The mechanism of genetic transformation in bacteria.

A
  1. Recipient cell takes up donor DNA.
  2. Donor DNA aligns with complementary
    bases.
  3. Recombination occurs between donor DNA and recipient DNA.
143
Q

Define Conjugation.

A

Plasmids transferred from one
bacterium to another.

144
Q

What does conjugation require?

A

It requires cell-to-cell contact via sex pili.

145
Q

What type of cells carry the plasmid (F factor) and are called F+ cells?

A

Donar cells

146
Q

What type of cells contain the F factor on the chromosome?

A

Hfr cells

147
Q

True or False: When an F factor (a plasmid) is transferred from a donor (F+) to a recipient (F–), the F– cell is converted to an F+ cell.

A

True

148
Q

True or False: When an F factor becomes integrated into the chromosome of an F+ cell, it makes the cell a high frequency of recombination (Hfr) cell.

A

True

149
Q

DNA is transferred from a donor cell to a recipient via a ______________.

A

Bacteriophage

150
Q

Define Generalized transduction.

A

Random bacterial DNA is packaged inside a phage and transferred to a recipient cell.

151
Q

Transduction by a bacteriophage

A
  1. A phage infects the donor bacterial cell.
  2. Phage DNA and proteins are made,
    and the bacterial chromosome is broken into pieces.
  3. Occasionally during phage assembly,
    pieces of bacterial DNA are packaged in a phage capsid. Then the donor cell lyses and releases phage particles containing bacterial DNA.
  4. A phage carrying bacterial DNA infects
    a new host cell, the recipient cell.
  5. Recombination can occur, producing a
    recombinant cell with a genotype different
    from both the donor and recipient cells.
152
Q

_________ are self-replicating
circular pieces of DNA.

A

Plasmids

153
Q

___ to ____% the size of a bacterial
chromosome

A

1 to 5

154
Q

What often codes for proteins that
enhance the pathogenicity of
a bacterium?

A

Plasmids

155
Q

What is a Conjugative plasmid?

A

Carries genes for sex pili and
transfer of the plasmid.

156
Q

What are the resistant factors (R factors) of plasmids?

A

Encode antibiotic
resistance

157
Q

What are Transposons?

A

Segments of DNA that can move from
one region of DNA to another.

158
Q

Transposons contain _____________ that code for transposase that cuts and reseals DNA.

A

Insertion sequences (IS)

159
Q

Complex transposons carry other _____ (e.g, in antibiotic resistance).

A

Genes

160
Q

Mutations and recombination create ________________.

A

Cell diversity

161
Q

________________ acts on populations of organisms to ensure the survival of organisms fit for a particular environment.

A

Natural selection

162
Q

General characteristics of Viruses

A
  1. Obligatory intracellular parasites
    - Require living host cells to multiply
  2. Contain DNA or RNA
  3. Contain a protein coat
  4. No ribosomes
  5. No ATP-generating mechanism
163
Q

What is the Host range?

A

The spectrum of host cells a virus can infect.

164
Q

Most viruses infect only ________ types of cells in one host.

A

Specific

165
Q

What is virus infection determined by?

A

Determined by specific host attachment sites and cellular factors.

166
Q

What are Bacteriophages?

A

Viruses that infect bacteria

167
Q

What is the size range of bacteriophages?

A

Range from 20 nm to 1000 nm in length

168
Q

Virus Sizes

A
  1. Bacteriophages f2, MS2 - 24 nm
  2. Poliovirus - 30 nm
  3. Rhinovirus - 30 nm
  4. Adenovirus - 90 nm
  5. Rabies virus - 170 x 70 nm
  6. Prion - 200 x 20 nm
  7. Bacteriophage T4 - 225 nm
  8. Tobacco mosaic virus - 250 x 18 nm
  9. Viroid - 300 x 10 nm
  10. Vaccinia virus - 300 x 200 x 100 nm
  11. Bacteriophage M13 - 800 x 10 nm
  12. Ebola virus - 970 nm
  13. Chlamydia bacterium elementary body - 300 nm
  14. E. coli bacterium - 3000 x 1000 nm
  15. Human red blood cell - 10,000 nm in diameter
  16. Plasma membrane of red blood cell - 10 nm thick
169
Q

What is a Virion?

A

Complete, fully developed viral particle

170
Q

What parts make up the virion?

A
  1. Nucleic acid—DNA or RNA can be single or double-stranded; linear or circular.
  2. Capsid—protein coat made of capsomeres (subunits).
  3. Envelope—lipid, protein, and carbohydrate coating on some viruses.
  4. Spikes—projections from the outer surface.
171
Q

How are viruses classified?

A
  1. Nucleic acid (size, type, structure)
  2. Replication strategy
  3. Capsid symmetry
  4. Envelope (+ or -)
172
Q

The _________ of viruses is
unclear, so they can’t be
classified in the same way as
cellular organisms.

A

Phylogeny

173
Q

Different suffixes indicate
taxonomic level, beginning
with ________.

A

Family

174
Q

“Species” name of pathogenic
viruses are generally associated
with the _________ they cause.

A

Disease

175
Q

Ending for virus family

A

-Viridae

176
Q

Ending of virus subfamily

A

-Virinae

177
Q

Ending of virus genus

A

-Virus

178
Q

Viruses must grow in what?

A

Live cells

179
Q

Bacteriophages are grown in what?

A

Bacteria

180
Q

Bacteriophages form _______, which are clearings on a lawn of bacteria on the surface of the agar.

A

Plaques

181
Q

Each plaque corresponds to a single virus; can be expressed as _________________________.

A

Plaque-forming units (PFU)

182
Q

What are 3 important factors in growing animal viruses in the laboratory?

A
  1. In living animals
  2. In embryonated eggs
    - Virus injected into the egg.
    - Viral growth is signaled by changes or death of the embryo.
  3. In cell cultures
    - Tissues are treated with enzymes to separate cells.
    - Virally infected cells are detected via their deterioration, known as the cytopathic effect (CPE).
    - Continuous cell lines are used.
183
Q

Cell cultures

A
  1. A tissue is treated with enzymes
    to separate the cells.
  2. Cells are suspended in a culture medium.
  3. Normal cells or primary cells grow in a monolayer across the glass or plastic container. Transformed cells or continuous cell cultures do not grow in a monolayer.
184
Q

What are the factors of viral identification?

A
  1. Cytopathic effects
  2. Serological tests
    - Western blotting—reaction of the virus with antibodies
  3. Nucleic acids
    - RFLPs (restriction fragment length polymorphisms)
    - PCR
185
Q

A Western Blot uses antibodies to detect specific proteins in a mixture

A
  1. Proteins (in a mixture) are separated by size using gel electrophoresis.
  2. Separated proteins are transferred from the gel to a “membrane,” maintaining their pattern of separation (this is the
    “blotting” part).
  3. Proteins of interest in the mixture are bound to a “primary” antibody that recognizes them.
  4. The primary antibody is visualized
    using a “secondary” antibody coupled
    to an enzyme.
  5. The enzyme is exposed to its
    substrate and catalyzes a reaction
    that produces detectable light.
186
Q

A Western Blot (immunoblot) can be
used _____________ as well as in research.

A

Diagnostically

187
Q

A Western Blot is used to confirm an HIV-positive diagnosis by detecting _______________________________.

A

Serum antibodies to the virus

188
Q

In the Western Blot test, the
patient’s own _______ is the source of
“primary” anti-HIV antibodies.

A

Serum

189
Q

If those antibodies are present (i.e. if the patient has HIV), they will cause __________________________________________________.

A

The HIV proteins on the membrane to “light up.”

190
Q

For a virus to multiply….

A
  1. It must invade a host cell.
  2. It must take over the host’s metabolic machinery.
    *One-step growth curve
191
Q

Define Attachment (lytic cycle).

A

Phage attaches by the tail fibers to the host cell.

192
Q

Define Penetration (lytic cycle).

A

Phage lysozyme opens the cell wall; tail sheath contracts to force the tail core and DNA into the cell.

193
Q

Define Biosynthesis (lytic cycle).

A

Production of phage DNA and
proteins.

194
Q

Define Maturation (lytic cycle).

A

Assembly of phage particles.

195
Q

Define Release (lytic cycle).

A

Phage lysozyme breaks the cell wall.

196
Q

What happens during the Lytic cycle?

A

Phage causes lysis and death of the host cell.

197
Q

What happens during the Lysogenic cycle?

A
  1. Specialized transduction
  2. Phage DNA incorporates into host cell DNA
    - When the host cell replicates its chromosome, it also replicates prophage DNA.
198
Q

Define Lysogeny.

A

Phage remains latent.

199
Q

Define Prophage.

A

Inserted phage DNA.

200
Q

What are the important results of the lysogenic cycle?

A
  1. The cells become immune to reinfection by the same phage.
  2. Phage conversion—the host cell exhibits new properties
    (some bacteria produce toxins only when it carries a lysogenic phage).
201
Q

Define Attachment (x animal virus).

A

Viruses attach to the cell membrane.

202
Q

Define Penetration (x animal virus).

A

Entry by receptor-mediated endocytosis or fusion.

203
Q

_________ by viral or host enzymes.

A

Uncoating

204
Q

Define Biosynthesis (x animal virus).

A

Production of nucleic acid and proteins.

205
Q

Define Maturation (x animal virus).

A

Nucleic acid and capsid proteins assemble.

206
Q

Define Release (x animal virus).

A

Release by budding (enveloped viruses) or rupture (non-enveloped viruses).

207
Q

DNA viruses _______ their DNA in the nucleus of the host
using viral enzymes.

A

Replicate

208
Q

_____________ capsid in the cytoplasm using host cell enzymes.

A

Synthesize

209
Q

Replication of Animal Viruses

A

Attachment -> Entry and Uncoating -> Portion of DNA transcribed and mRNA produced -> Biosynthesis -> Late translation -> Maturation -> Release

210
Q

The virus multiplies in the host cell’s cytoplasm using
______________________.

A

RNA-dependent RNA polymerase

211
Q

ssRNA; + (sense) strand

A

Viral RNA serves as mRNA for protein synthesis.

212
Q

ssRNA; – (antisense) strand

A

Viral RNA is transcribed to a + strand to serve as mRNA for protein synthesis.

213
Q

What is dsRNA?

A

double-stranded RNA

214
Q

Pathways of multiplication used by various RNA-containing viruses.

A

Attachment -> Entry and Uncoating -> RNA replication -> Translation and synthesis of viral proteins -> Maturation

215
Q

Single-stranded RNA, produce _______

A

DNA

216
Q

Use___________________ to produce DNA from the
viral genome.

A

Reverse transcriptase

217
Q

Viral DNA integrates into the host chromosome as a _________.

A

Provirus

218
Q

Examples of Retroviridae.

A
  1. Lentivirus (HIV)
  2. Oncoviruses
    - Viral RNA is transcribed to DNA (using reverse
    transcriptase), which can integrate into host DNA.
    • HTLV-1 and HTLV-2 cause adult T cell leukemia and lymphoma.
219
Q

Several types of _______ are caused by viruses.

A

Cancer

220
Q

How are cancers caused by viruses?

A
  1. May develop long after a viral infection.
  2. Cancers caused by viruses are not contagious.
221
Q

What is a Sarcoma?

A

Cancer of connective tissue.

222
Q

What are Adenocarcinomas?

A

Cancers of glandular epithelial tissue.

223
Q

__________ transform normal cells into cancerous
cells.

A

Oncogenes

224
Q

______________ become integrated into the
host cell’s DNA and induce tumors (Adenoviridae,
Epstein-Barr virus, Human papillomavirus,
Hepatitis B virus).

A

Oncogenic viruses

225
Q

A transformed cell harbors a _________________________ on the surface and a
T antigen in the nucleus.

A

Tumor-specific transplant antigen (TSTA)

226
Q

Latent virus remains in _____________ host cell for
long periods.

A

Asymptomatic

227
Q

A ___________ viral infection occurs gradually over
a long period; is generally fatal.
Ex: Subacute sclerosing panencephalitis (measles virus)

A

Persistent

Microbiology (5 decks)

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