microbiology ch 8 Flashcards
1
Q
What is genetics?
A
The study of genes, how they carry information, how information is expressed, and how genes are replicated
2
Q
What is genetics also known as?
A
The science of heredity
3
Q
What is a genome?
A
All the genetic information in a cell
4
Q
What are genes?
A
Segments of DNA that encode functional products, usually proteins
5
Q
What are chromosomes?
A
Structures containing DNA that physically carry hereditary information
6
Q
What do chromosomes contain?
A
Genes
7
Q
This is the study of genes, how they carry information, how information is expressed, and how genes are replicated; also known as the science of heredity
A
Genetics
8
Q
This is all the genetic information in a cell
A
Genome
9
Q
These are segments of DNA that encode functional products (usually proteins)
A
Genes
10
Q
These are structures containing DNA that physically carry hereditary information
A
Chromosomes
11
Q
What is the genetic code?
A
A set of rules that determines how a nucleotide sequence is converted to an amino acid sequence of a protein
12
Q
What is the central dogma?
A
Sequence of nucleotides in DNA determine the sequence of amino acids in a protein
13
Q
This is a set of rules determining how a nucleotide sequence is converted to an amino acid sequence of a protein
A
Genetic code
14
Q
This says that the sequence of nucleotides in DNA determines the sequence of amino acids in a protein
A
Central dogma
15
Q
What is a genotype?
A
The genetic makeup of an organism
16
Q
What is a phenotype?
A
An expression of an organism’s genes
17
Q
Does a genotype represent an organism’s potential properties?
A
Yes
18
Q
Does a genotype represent an organism’s expressed properties?
A
No
19
Q
This is the genetic makeup of an organism
A
Genotype
20
Q
This is the expression of an organism’s genes
A
Phenotype
21
Q
Does a phenotype represent an organism’s potential properties?
A
No
22
Q
Do bacteria have a single circular chromosome made of DNA and associated proteins?
A
Yes
23
Q
What are short tandem repeats (STRs)?
A
Repeating sequences of noncoding DNA
24
Q
Do bacterial genomes contain back-to-back genes?
A
No
25
These usually have a single circular chromosome made of DNA and associated proteins
Bacteria
26
These are repeating sequences of noncoding DNA
Short tandem repeats (STRs)
27
What is vertical gene transfer?
The flow of genetic information from one generation to the next
28
What is horizontal gene transfer?
The transfer of genetic information between two organisms in the same generation
29
This is the flow of genetic information from one generation to the next
Vertical gene transfer
30
This is the transfer of genetic information between two organisms in the same generation
Horizontal gene transfer
31
What happens during DNA replication?
One parental double-stranded DNA molecule is converted into two identical offspring molecules
32
What is semiconservative replication?
When each double-stranded DNA molecule contains one original strand and one new strand
33
During this, one "parental" double-stranded DNA molecule is converted into two identical offspring molecules
DNA replication
34
This is when each double-stranded DNA molecule contains one original strand and one new strand
Semiconservative replication
35
What shape does a DNA molecule form?
Double helix
36
What does the 'backbone' of the DNA double helix consist of?
Deoxyribose-phosphate
37
How are the two strands of the DNA double helix held together?
By hydrogen bonds between A-T and C-G
38
What forms the genetic instructions of the organism?
Order of the nitrogen-containing bases
39
This forms a double helix
DNA molecule
40
This part of DNA consists of deoxyribose-phosphate
DNA 'backbone'
41
These are held together by hydrogen bonds between A-T and C-G
Two strands of nucleotides in DNA double helix
42
This forms the genetic instructions of the organism
Order of nitrogen-containing bases
43
In DNA replication, what does one strand serve as?
A template for the production of a second strand
44
What two enzymes relax the strands in DNA replication?
Topoisomerase and gyrase
45
What enzyme separates the strands during DNA replication?
Helicase
46
What do topoisomerase and gyrase do during DNA replication?
Relax the DNA strands
47
What does helicase do during DNA replication?
Separates the DNA strands
48
What three roles does DNA polymerase have during DNA replication?
Adds nucleotides to growing DNA strand; removes RNA primers, joins Okazaki fragments (along with DNA ligase)
49
What direction does DNA polymerase go in during DNA replication?
5 --> 3'
50
What initiates DNA synthesis during replication?
RNA primer
51
Is the leading strand of synthesized continuously during DNA replication?
Yes
52
Is the lagging strand synthesized continuously during DNA replication?
No
53
What enzyme removes RNA primers?
DNA polymerase
54
What two enzymes join Okazaki fragments?
DNA polymerase and DNA ligase
55
What enzyme adds nucleotides to the growing DNA strand?
DNA polymerase
56
Does DNA polymerase add nucleotides to the growing DNA strand in a 3' to 5' direction?
No
57
How is the leading strand synthesized in DNA replication?
Continuously
58
Does synthesis of the lagging strand by DNA polymerase create Okazaki fragments?
Yes
59
How is the lagging strand synthesized in DNA replication?
Discontinuously
60
Does synthesis of the leading strand by DNA polymerase create Okazaki fragments?
No
61
Is the leading strand synthesized discontinuously in DNA replication?
No
62
Is the lagging strand synthesized discontinuously in DNA replication?
Yes
63
What are Okazaki fragments?
Sections of DNA synthesized on the lagging strand by DNA polymerase
64
What supplies the energy for DNA replication?
Nucleotides
65
What process provides energy from nucleotides for DNA replication?
Hydrolysis of two phosphate groups on nucleotides
66
What direction does most bacterial DNA replication go in?
Bidirectional
67
How many copies of the DNA molecule does each offspring cell receive?
1
68
What makes replication so accurate?
Proofreading capability of DNA polymerase
69
Is most bacterial DNA replication unidirectional?
No
70
Does each offspring cell receive 2 copies of the DNA molecule?
No
71
What does the proofreading capability of DNA polymerase ensure?
That replication is highly accurate?
72
What three components distinguish RNA from DNA
Single-stranded nucleotide; 5-carbon ribose sugar; Uracil instead of thymine
73
This molecule is made up of a single-stranded nucleotide, a 5-carbon ribose sugar, and uracil rather than thymine
Ribonucleic acid (RNA)
74
This form of RNA is an integral part of ribosomes
Ribosomal RNA (rRNA)
75
This form of RNA transports amino acids during protein synthesis
Transfer RNA (tRNA)
76
This form of RNA carries coded information from DNA to ribosomes
Messenger RNA (mRNA)
77
What is the function of ribosomal RNA (rRNA)?
Forms an integral part of ribosomes
78
What is the function of transfer RNA (tRNA)?
Transports amino acids during protein synthesis
79
What is the function of messenger RNA (mRNA)?
Carries coded information from DNA to ribosomes
80
What is transcription?
Synthesis of a complementary mRNA strand from a DNA template
81
When does transcription begin?
When RNA polymerase binds to the promoter sequence on DNA
82
What direction does transcription go in?
5 --> 3
83
How many DNA strands are transcribed by RNA polymerase?
1 of 2
84
When does transcription stop?
When RNA polymerase reaches the terminator sequence on DNA
85
This is the synthesis of a complementary mRNA strand from a DNA template
Transcription
86
RNA polymerase binding to the promoter sequence on DNA begins this process
Transcription
87
Are both DNA strands transcribed by RNA polymerase?
No
88
Does transcription proceed in the 5 --> 3 direction?
Yes
89
What happens when RNA polymerase reaches the terminator sequence on DNA?
Transcription stops
90
What is mRNA translated into?
The 'language' of proteins
91
What are codons?
Groups of three mRNA nucleotides that code for a particular amino acid
92
How many codons are there?
64
93
How many amino acids are there?
20
94
How many sense codons encode the 20 amino acids?
61
95
How many 'nonsense' or stop codons are there?
3
96
What is it mean that the genetic code involves degeneracy?
Each amino acid is coded by several codons (redundancy)
97
This is translated into the 'language' of proteins
mRNA
98
These are groups of three mRNA nucleotides that code for a particular amino acid
Codons
99
These codons encode the 20 amino acids
Sense codons
100
These codons do not encode for amino acids
Nonsense/stop codons
101
This feature of the genetic code means that each amino acid is coded by several codons and therefore has redundancy
Degeneracy
102
Which codon does translation of mRNA begin with?
Start codon AUG
103
Which three codons does translation of mRNA end with?
Nonsense/stop codons UAA, UAG, or UGA
104
How are mRNA codons 'read'
Sequentially
105
The start codon AUG begins this process
Translation of mRNA
106
Nonsense/stop codons UAA, UAG, or UGA stop this process
Translation of mRNA
107
These are 'read' sequentially during mRNA translation
Codons
108
These transport the required amino acids to the ribosome during translation
tRNA molecules
109
tRNA molecules have these that base-pair with the codon
Anticodon
110
These are joined by peptide bonds during translation
Amino acids
111
In bacteria, can translation begin before transcription is complete?
Yes
112
Where does transcription occur in eukaryotes?
In the nucleus
113
Where does translation occur in eukaryotes?
Cytoplasm
114
What are exons?
Regions of DNA that code for proteins
115
What are introns?
Regions of DNA that do not code for proteins
116
What do small nuclear ribonucleoproteins (snRNPs) do?
Remove introns and splice exons together
117
These are regions of DNA that code for proteins
Exons
118
These are regions of DNA that do not code for proteins
Introns
119
These remove introns and splice exons together
Small nuclear ribonucleoproteins (snRNPs)
120
What type of bacterial genes are expressed at a fix rate?
Constitute genes
121
What two types of bacterial genes are expressed only as needed?
Inducible and repressible genes
122
This inhibits gene expression and decreases enzyme synthesis
Repression
123
What are repressors?
Proteins that block transcription
124
What is the default position of a repressible gene?
On
125
This turns on gene expression
Induction
126
What is induction initiated by?
An inducer
127
What is the default position of an inducible gene?
Off
128
This is a segment of DNA where RNA polymerase initiates transcription of structural genes
Promoter
129
This is a segment of DNA that controls transcription of structural genes
Operator
130
This is a set of operator and promoter sites and the structural genes they control
Operon
131
In the operon model of gene expression, what is a promoter?
Segment of DNA where RNA polymerase initiates transcription of structural genes
132
In the operon model of gene expression, what is an operator?
Segment of DNA that controls transcription of structural genes
133
In the operon model of gene expression, what is an operon?
Set of operator and promoter sites and the structural genes they control
134
What happens in repressible operons?
Structural genes are transcribed until they are turned off
135
In these, structural genes are transcribed until they are turned off
Repressible operons
136
What does a corepressor do?
Binds and activates the repressor to bind to the operator, stopping synthesis of an amino acid
137
This binds and activates the repressor to bind to the operator, stopping synthesis of an amino acid
Corepressor
138
In this, structural genes are not transcribed unless an inducer is present
Inducible operon
139
What happens in an inducible operon?
Structural genes are not transcribed unless an inducer is present
140
What does catabolite repression do?
Inhibits cells from using carbon sources other than glucose
141
What builds up in a cell when glucose is not available?
Cyclic AMP (cAMP)
142
What does cAMP do?
Binds to the catabolic activator protein (CAP) that in turn binds to the lac promoter, initiating transcription and allowing the cell to use lactose
143
This inhibits cells from using carbon sources other than glucose
Catabolite repression
144
This builds up in a cell when glucose is not available
Cyclic AMP (cAMP)
145
This binds to the catabolic activator protein (CAP)
Cyclic AMP (cAMP)
146
What does the cAMP and CAP binding to the lac promoter do?
Initiates transcription and allows the cell to use lactose
147
What do methylating nucleotides do?
Turn genes off
148
Can methylated (off) genes be passed to offspring cells?
Yes
149
Is epigenetic control permanent?
No
150
These nucleotides turn genes off
Methylating nucleotides
151
These can be passed to offspring cells and are not permanent
Methylated (off) genes
152
What do microRNAs (miRNAs) do?
Base pair with mRNA to make it double-stranded
153
What happens to double-stranded RNA?
It is enzymatically destroyed, preventing production of a protein
154
What is the riboswitch?
A part of an mRNA molecule that binds to a substrate and changes the mRNA structure
155
What does the riboswitch do to translation?
Initiates or stops it
156
These base pair with mRNA to make it double stranded and enzymatically destroyed
MicroRNAs (miRNAs)
157
This is a part of an mRNA molecule that binds to a substrate and changes the mRNA structure, initiating or stopping translation
Riboswitch
158
What is a mutation?
A permanent change in the base sequence of DNA
159
What are mutagens?
Agents that cause mutations
160
What are spontaneous mutations?
Mutations that occur in the absence of a mutagen
161
This is a permanent change in the base sequence of DNA that may be neutral, beneficial, or harmful?
Mutation
162
These are agents that cause mutations
Mutagen
163
These mutations occur in the absence of a mutagen
Spontaneous mutations
164
What happens with base substitutions (point mutations)?
One base in DNA changes
165
In this type of mutation, there is a change in one base in DNA
Base substitution (point mutation)
166
What happens in a missense mutation?
Base substitution results in change in an amino acid
167
In this type of mutation, a base substitution results in change in an amino acid
Missense mutation
168
What happens in a nonsense mutation?
Base substitution results in a nonsense (stop) codon
169
In this type of mutation, a base substitution results in a nonsense (stop) codon
Nonsense mutation
170
What happens in a frameshift mutation?
The insertion or deletion of one or more nucleotide pairs shifts the transitional 'reading frame'
171
In this type of mutation, the insertion or deletion of one or more nucleotide pairs shifts the translational 'reading frame'
Frameshift mutation
172
What are three categories of mutagens?
Radiation, chemical, infections agents
173
What are two examples of radiation mutagens?
UV and X-rays
174
What are five examples of chemical mutagens?
Carcinogens, processed foods, preservatives, cosmetics, and cleaning products
175
What are two examples of infectious mutagens?
Viruses and bacteria
176
How does nitrous acid work as a mutagen?
Causes adenine to bind with cystosine instead of thymine
177
How do nucleoside analogs work as mutagens?
By incorporating into DNA in place of a normal base and causing mistakes in base pairing
178
How is nitrous acid emitted into the air?
By burning fossils fuels
179
What are nucleoside analogs used in?
Treatment of cancer and HIV
180
This mutagen causes adenine to bind with cytosine instead of thymine
Nitrous acid
181
This mutagen incorporates into DNA in place of a normal base and causes mistakes in base pairing
Nucleoside analog
182
How does ionizing radiation work as a mutagen?
Causes formation of ions that can oxidize nucleotides and break the deoxyribose-phosphate backbone
183
What causes thymine dimers?
Ultraviolet radiation
184
This type of mutagen causes formation of ions that can oxidize nucleotides and break the deoxyribose-phosphate backbone
Ionizing radiation
185
This type of radiation causes thymine dimers
Ultraviolet radiation
186
What is the spontaneous mutation rate?
1 in 10 replicated genes
187
What does positive (direct) selection do?
Detects mutant cells as they grow or appear different than unmutated cells
188
What does negative (indirect) selection do?
Detects mutant cells that cannot grow or perform a certain function
189
What is an auxtotroph?
Mutant that has a nutritional requirement absent in the parent
190
This type of mutation identification detects mutant cells because they grow or appear different than unmutated cells
Positive (direct) selection
191
This type of mutation identification detects mutant cells that cannot grow or perform a certain function
Negative (indirect) selection
192
This type of mutant has a nutritional requirement absent in the parent
Auxtotroph
193
What are carcinogens?
Substances that cause cancer in animals, including humans
194
What does the Ames test do?
Exposes mutant bacteria to mutagenic substances to measure the rate of reversal of the mutation
195
What does the Ames test indicate?
The degree to which a substance is mutagenic
196
These are substances that cause cancer in animals, including humans
Carcinogens
197
This test exposes mutant bacteria to mutagenic substances to measure the rate of reversal of the mutation
Ames test
198
This test indicates the degree to which a substance is mutagenic
Ames test
199
What is genetic recombination?
Exchange of genes between two DNA molecules
200
What does genetic recombination create?
Genetic diversity
201
What is one mechanism of genetic recombination?
Crossing over
202
What happens in crossing over?
Two chromosomes break and rejoin, resulting in the insertion of foreign DNA into the chromosome
203
This is the exchange of genes between two DNA molecules and creates genetic diversity
Genetic recombination
204
This is a mechanism of genetic recombination in which two chromosomes break and rejoin, resulting in the insertion of foreign DNA into the chromosome
Crossing over
205
What are plasmids?
Self-replicating circular pieces of DNA
206
How large are plasmids?
1 to 5% the size of a bacterial chromosome
207
What do plasmids often code for?
Proteins that enhance the pathogenicity of a bacterium
208
These are self-replicating circular pieces of DNA, 1 to 5% the size of a bacterial chromosome
Plasmids
209
These often code for proteins that enhance the pathogenicity of a bacterium
Plasmids
210
What do conjugative plasmids (F factors) carry genes for?
Sex pili and transfer of the plasmid
211
What do dissimilation plasmids encode?
Enzymes for the catabolism of unusual compounds, such as petroleum
212
What do resistance factors (R factors) encode?
Antibiotic resistance
213
What does resistance transfer factor (RTF) have genes for?
Plasmid replication and conjugation
214
What does R-determinant have?
Resistance genes
215
This type of plasmid carries genes for sex pili and transfer of the plasmid
Conjugative plasmids (F factors)
216
These encode enzymes for the catabolism of unusual compounds, such as petroleum
Dissimilation plasmids
217
These encode antibiotic resistance
Resistance factors (R factors)
218
These include genes for plasmid replication and conjugation
Resistance transfer factor (RTF)
219
This has the resistance genes
R-determinant
220
What are transposons?
Segments of DNA that can move from one region of DNA to another
221
Do transposons occur in prokaryotic organisms?
Yes
222
Do transposons occur in eukaryotic organisms?
Yes
223
What do transposons contain?
Insertion sequences that code for transposase that cuts and reseals DNA
224
What do complex transposons carry?
Other genes (e.g. antibiotic resistance)
225
These are segments of DNA that can move from one region of DNA to another and contain insertion sequences that code for transposase
Transposons
226
What does transposase do?
Cuts and reseals DNA
227
These transposons carry other genes, such as for antibiotic resistance
Complex transposons
228
What happens in bacterial conjugation?
Plasmids are transferred from one bacterium to another
229
What does conjugation in bacteria require?
Cell-to-cell contact via sex pili
230
This is when plasmids are transferred from one bacterium to another
Conjugation
231
This requires cell-to-cell contact via sex pili
Conjugation
232
What are F+ cells?
Donor cells that carry the plasmid F factor
233
What are recipient cells in bacterial conjugation called?
F- cells
234
What do Hfr (high frequency of recombination) cells contain?
F factor on the chromosome
235
These are donor cells that carry the plasmid (F factor)
F+ cells
236
What are recipient cells called prior to conjugation?
F- cells
237
These F factor-carrying cells have the factor integrated into the chromosome
Hfr (high frequency of recombination) cells
238
What is DNA transferred through from a donor cell to a recipient?
Bacteriophage
239
What is generalized transduction?
Random bacterial DNA is packaged inside a phage and transferred to a recipient cell
240
What is specialized transduction?
Specific bacterial genes are packaged inside a phage and transferred to a recipient cell
241
In this type of transduction, random bacterial DNA is packaged inside a phage and transferred to a recipient cell
Generalized transduction
242
In this type of transduction, specific bacterial genes are packaged inside a phage and transferred to a recipient cell
Specialized transduction
243
What do mutations and recombination create?
Cell diversity
244
What is the raw material for evolution?
Diversity
245
These create cell diversity
Mutations and recombinations
246
Diversity is the raw material for this
Evolution
