MicroBio Chapter 8: Bacterial Genetics
An auxotroph can be isolated from a prototrophic parent strain by ____ selection.
indirect
Chemical mutagens that squeeze between base pairs and induce frameshift mutation are called ____.
intercalating agent
Random genetic changes that result from normal cellular processes are ____.
spontaneous mutations
Mutagens that are DNA segments that insert themselves into genes and inactivates them are called ____.
transposons
Chemical mutagens can cause which of the following? -Base substitutions -Frameshift mutations -Double stranded breaks -Thymine dilmers
-Base substitutions -Frameshift mutations
Recognition and repair of errors in nucleotides incorporation by DNA polymerase is called ____.
proofreading
Bacteria are a great model system for genetic studies because when they are grown to very high numbers is small volumes of sample media ____.
rare genetic changes that happen can be easily studied
Modified nucleobases can result in ____ if they are not repaired before DNA replication occurs.
base substitution
Genes into which transposons "jump" are usually ____ by the event.
inactivated
After new virus particles have assembled in the bacterial host cell, they are usually ____.
released as a result of host cell lysis
The common consequences of a ____ mutation is the appearance of an appearance of an early stop codon that produces a shortened and thus non-functional proteins
frameshift
____ structurally resemble nucleobases and can be mistakenly used when cells make nucleotides, which are then incorporated by DNA polymerase into DNA.
Base analogs
Chemicals that cause cancer are called ____, and most of them are ____.
Blank 1: carcinogens Blank 2: mutagens
True of False: Vertical gene transfer is the transfer of gene from one organism to another in a population, while horizontal gene transfer is the transfer of genes from cell to progency
False
True or False: Ultraviolet rays are chemical mutagens.
False
The ____ is the observed characteristics of an organism.
Phenotype
A process that breaks the covalent bonds that have formed between thymines to create thymine dimers.
Photoreactivation
____ repair is activated by extensive DNA damage and uses a polymerase that lacks proofreading ability, ultimately resulting in mutations.
SOS
Spontaneous mutations are important because ____.
They allow populations of bacteria to adapt to a changing environment
True or False: Incorporation of an incorrect nucleotides in a molecule of DNA results in a distortion of the DNA helix can be detected by repair enzymes.
True
True or False: The native or wild type strain describes the typical phenotype of strains isolated from nature.
True
____ are a type of radiation that can cause single and double stranded breaks in a DNA strand.
X rays
When treating tuberculosis, two or more antimicrobial medication are often prescribed because ____.
a sensitive cell is unlikely to become resistant to two medications simultaneously through separate spontaneous mutations
Selecting penicillin-resistant mutants by plating them on a medium containing penicillin is an example of _____ selection.
direct
A base substitution that results in a change in the amino acid encoded is called a(n)____ mutation.
missense
A base substitution that changes an amino acid-encoding is called a(n)____ mutation.
nonsense
Chemical mutagens that modify ____ increase the odds of incorrect nucleotides incorporation during DNA replication.
nucleobases
A ____ mutation occurs if a single base pair is changed during DNA synthesis
point
If a scientist is working with bacteria that have the typical phenotype of those isolated from nature, the bacteria are considered to be ____ type.
wild
A mutation frequently results in the production of a shortened and non-functional protein because a different set of codons is translated.
Frameshift mutation
The two types of transduction.
-Specialized -Generalized
The consequences of not repairing damaged DNA in cells include ____. -cell death -increased activity of the RNA polymerase -cells that have fewer mutations -cancer (in animals)
-cell death -cancer (in animals)
Mutations are rare because -damage to DNA is very uncommon event -mutated DNA cannot replicated, so it cannot be passed to progency -most damage is repaired before it is passed on to progency
-most damage is repaired before it is passed on to progency
The return of a gene from a mutated state to its original, non-mutated state is called a _____.
reversion
A base substitution that results in a codon that still codes for the wild type amino acid is called a(n) ____ mutation.
silent
Bacteriophage can consist of ____. -Nucleus -DNA genome -Hybrids DNA/RNA genome -Membrane (envelope) -RNA genome -Protein coats (capsid)
-DNA genome -RNA genome -Protein coats (capsid)
Which is an agent that induces changes in DNA? -Mutation -Mutant -Mutagen
-Mutagen
Genetic change in bacteria occurs through which two mechanism?
-Mutation -Horizontal gene transfer
In bacterial conjugation, a donor cell with an F ____ is considered F+. -Plasmid -Fimbria -Chromosome -Complex -Pilus
-Plasmid
The distortion of DNA by thymine dimers directly blocks which of the following cellular process? -Translation -Transcription -Respiration -Replication
-Replication -Transcription
The general mechanism by which most bacteria routinely respond to new circumstances are _____ change and regulating ____ expression.
Blank 1: genetic Blank 2: gene
Repair of nucleotide incorporation errors during the process of DNA replication is accomplished by ____ by DNA polymerase and by ____ repair.
Blank 1: proofreading Blank 2: mismatch
True or False: a point mutation always lead to a shift of one reading frame from the point of mutation downstream.
False
Term describes the sequence of nucleotides (genetic makeup) of an organism or a cell.
Genotype