8: Bacterial Genetics Flashcards
Define auxotroph
A microorganism that requires an organic growth factor. Ex. Amino acid
Define Bacterial Transformation
Mechanism of horizontal gene transfer in which naked DNA is taken up by the recipient cell. (Usually from environment)
Define Conjugation
Mechanism of horizontal gene transfer in which donor cell physically contacts the recipient cell.
Define Genotype
The sequence of nucleotides in an organisms DNA
Define Horizontal Gene Transfer
Transfer of DNA from one organism by a process other than reproduction.
Includes:
Conjugation
Transduction
Bacterial Transformation
Define mutation
A change in the nucleotide sequence of a cell’s DNA that is passed on to daughter cells.
Define Plasmid
A DNA molecule that replicates independently of the chromosome.
Define Prototroph
A microorganism that does not require any organic growth factors.
(Opposite of auxotroph)
Define Transduction
Mechanism of horizontal gene transfer in which bacterial DNA is transferred inside a phage coat.
Define Transposable Element
Segment of DNA that can move from one site to another in a cells genome.
Define vertical gene transfer.
Transfer of DNA from parent to offspring.
Define strain(s).
Genetic variants within a species.
What are the two mechanisms bacteria use to change their genetic code?
Mutation, horizontal gene transfer.
What’s the convention for writing strains of bacteria?
Define spontaneous mutation. What does this mean for a colony?
Random genetic change that results from normal cell processes and are passed to offspring.
This means colonies usually are never exactly identical.
Define reversion.
A mutation that reverts a strain back to its original, non-mutated state.
Define Base-pair substitution. How can this occur?
A type of point mutation that replaces one of the base pairs with another.
This can occur from DNA polymerase incorporating an incorrect base.
Define Synonymous mutation.
Incorporation of the incorrect nucleotide creates a codon that encodes the same amino acid as the original code.
NOT necessarily a silent mutation as the mutation can still cause a change that affects efficiency of translation.
Define missense mutation.
Incorporation of the incorrect nucleotide creates a codon for a different amino acid.
Define nonesense mutation
Incorporation of the incorrect nucleotide creates a stop codon.
Often making protein non-functional.
Define frameshift mutation
Adding or subtracting anything amount of amino acids that isn’t 3. Change the reading frame for mRNA so an entirely different set of codons is translated.
Explain transposition. (Non-homologous recombination)
Integration into new location through a process that does not require a similar nucleotide sequence in the region of recombination.
Simply insertion into a stretch of DNA, does NOT replace the existing sequences.
Define what insertional inactivation is.
The outcome when transportation(non-homologous recombination) occurs and the gene is disrupted by the event, so the gene becomes non-functional.
Define induced mutation.
Genetic changes that occur due to an influence outside of a cell. Ex. Radiation or exposure to chemicals.
Define mutagen
An agent that induces the change/mutation of a bacteria.
Why are alkylating agents so mutagenic?
They add a methyl group/ other alkyl group onto bases. Which can cause mispairing.
Define Base Analogs
Structurally resemble the bases, but have different hydrogen bonding properties.These can be mistakenly used in place of the real bases. making complementary strand possible the wrong base as well.
Define intercalating agents
They Increase the frequency of frameshift mutations because they can insert(intercalate) between adjacent bases of DNA. Pushing nucleotides apart, making them more susceptible to insertions/deletions.
Define transposons
A type of transposable element, more detailed answers in further FC’s.
How does UV exposure affect DNA? Why is it considered mutagenic?
Causes covalent bonds to form between adjacent thymine dimers.
Making the strand unable to properly fit into a double helix. Stopping replication and transcription.
It’s major way of being mutagenic results form the cells attempt to repair the damage by SOS repair.
How does X Rays exposure affect DNA? Why is it considered mutagenic?
Causes single and double strand breaks in DNA, and they damage nucelobases.
Start back up at section 8.4
