Chapter 7 and 8: Microbial Metabolism and Genetics- Part 2 Flashcards
Staphylococcus aureus is a common gram ______ bacterium
Positive
Drug resistant S. aureus are called
Methicillin-resistant Staphylococcus aureus (MRSA)
Antibiotic resistance is a _______ event
Genetic
Bacteria have _______ genomes
Haploid (one chromosome)
Mutations in bacterial genes alters what?
Genotype
What is the genotype?
The DNA-level information encoded by the genome
Mutations can also alter…
Phenotype
What is the phenotype controlled by?
Proteins by alteration of amino acid composition
Organisms that acquire mutations are termed…
Mutants
What are the two types of mutations?
Induced
Spontaneous
Spontaneous mutations
During normal cellular processes
Types of spontaneous mutations
- Nucleotide base substitution (aka point mutation)
- Deletion or insertion of nucleotides
- Transposable elements (“jumping genes”)
Induced mutations
Chemicals and radiation can induce mutations of DNA
What are mutases?
A type of induced mutation, they are enzymes that are expressed during times of stress that increase rates of mutations
What do nonsense mutations do?
Switch something to a stop codon?
Mutations are a ______ biological process
Natural
All DNA polymerases have..
Inherent mutation rates
IN times of stress, mutational rates..
Increase
What would happen without mutations?
Evolution cannot occur and organisms will be ill-equipped to adjust to changes in their environment
Evolution requires what three events?
- Genetic variation, which is mostly random
- The variations must be heritable
- Natural selection of those traits most suitable for an environment
What are competent cells?
Cells that are receptive to DNA transfer
The process of becoming competent is largely unknown, but requires _______ ________
Protein synthesis
What do competent cells permit?
DNA to pass through their cell walls and membranes
What is transformation?
The process of competent cells allowing DNA to pass through their cell walls and membranes, can lead to the acquisition of new genes
Can competent cells be induced artificially?
Yes, they play an important role in biotechnology
DNA-mediated transformation has to do with…
Competence
Transduction
Bacteriophages frequently incorporate genes from previously-infected host cells
What happens when progeny viruses infect other bacteria?
The new genetic information can be recombined with the host’s genome
What are plasmids?
Circular pieces of DNA
How long are plasmids?
They can be hundreds to thousands of nucleotides long
Plasmids frequently contain _______ ______ that contribute to disease susceptibility
Virulence factors
Virulence factors (common)
Antibiotic resistance
Toxins
Why are plasmids considered promiscuous?
They can disseminate between species of bacteria
What are plasmids commonly used in biotechnology for?
Gene cloning and recombinant protein production
What is conjugation?
The direct transfer of plasmids (or chromosomes) between bacteria
Competent cells acquire plasmids by…
Random chance
Conjugation 4 Step Process: First Step
Contact between a donor cell (F+) and recipient cell (F-) is mediated by a sex pilus, a tubular structures
Conjugation 4 Step process: Step 2
The plasmid becomes mobilized by an enzyme that cleaves the plasmid
Conjugation 4 Step Process: Step 3
One strand of the double stranded plasmid is transferred to the recipient, presumably through the pilus
Conjugation 4 step process: Step 4
The copies of the plasmids are used as templates for DNA synthesis
Each strand of the plasmid has..
Enzymes to make another strand
Can penicillinase be passed through conjugation?
Yes and it makes organisms resistant to penicillin
Transposons
Transposable elements, jumping genes, are self-replicating DNA molecules
The mobile gene pool- transposons occur in…
Virtually all organisms
When transposons jump, they…
Frequently take adjacent genes with them, such that integration in another cell leads to the introduction of novel genetic information
(Slide #26)
