Microbial Genetics Flashcards
what are plasmids and what do they do
Small circles of ds DNA
Encode inessential genes that give the bacterium a selective adv.
An F+ bacteria means..
it is cabable of producing a pili
where does DNA replication/ transcription and translation take place in eukaryotes and prokaryotes
rep- Eukaroyes (nuclei), Pro (cytosol)
Transcription- Euk (nuclei), Pro (cytosol)
Translation- In cytosol
How does DNA replication start in eukaryotes
Starts @ origin
Helicase binds to origin and unwinds seperate DNA strands
Which direction does dna replication go and what are the 2 strands
occurs in 5 to 3 direction
leading strand- replicated continously towards fork
lagging strand- produces okazaki fragments away from fork
What are the enzymes needed in the replication process
- Primase is starting point for fragments
- DNA polymerase adds complementary nucleotides to new strand in 5 to 3 direction
- DNA ligase fills in any gaps
Overall one strand new and one old (semiconservative)
What are telomeres made of
hundreds of TTAGGG repeats at the end of eukaryotic dna to prevent loss of genes
How many origin points does prokaryotic DNA replication have
multiple
In bacteria what is the main enzyme involved in repication
DNA polymerase II
What is an aditional enzyme bacteria need for replication and function
Bacteria require DNA gyrase to resolve supercoils in its circular genome
What does topisomerase IV do in dna replication in bac
after replication it cuts and reseals the circular dna
What are the steps of rolling circle replication
- repA nicks outer strand
- DNA polmerase binds to intact strand which is used as template
- nicked strand displaced
- displaced strand is then coppied to dsDNA
How does viral dna replicate (3 ways)
- be used directaly as template
- linear dna circulizes in rolling circle replication
- Integrate into host genome
How do transcription factors (actiavtors/repressors) affect transcription
Need all the activators and no repressors
What seperates the strands in transcription
RNA polymerase
What does RNA pol I, II, III corespond to
I- rRNA
II- mRNA
III-tRNA
What are the post trascriptional modifications (4)
5’ cap
Poly A tail
removal of introns
alternative splicing
What are introns
regions of mRNA that do not code for proteins that need to be spliced out
what is alternative splicing
selected exons can be spliced out in order to have one section code for multiple pros
How are viral proteins translated
viruses utalize the ribosomes of the cells they infect to make their pros
(can also be translated into large polypros that are trimmed down into other functional pros via proteases)
What does RNA dependent polymerase do
allows viruses to amplify their dna by being able to convert from + sense to - sense and back
- in -sense they can amplify their rna
What are group 3 viruses and how do they amplify rna
DSRNA
has + and - strand
negative used to amplify then go back to positive to create pros
What are group 4 viruses and how do they amplify rna
(+) ssRNA
can change to - sense to amplify
What are group 5 viruses and how do they amplify rna
(-)ssRNA
can change to + to make pro or used as templates to create more +
What can group 6 and 7 viruses do
can convert its rna to dna
must convert into host dna after
What happens in binary fission and who performs it
cell elongates and divides into 2 identical daughter cells
-primary for bac, mito
Whatt happens in budding and who performs it
new organism develops from outgrowth or bud due to cell division at one site
-certain yeasts, molds, protozoa + helminths
What happens in fragmentation and who performs it
A piece of organism breaks off and fragment develops into matured organism
some pathogenic molds
Why would fungi perform sexual repro instead of asexual
fungal secual repro stage is usually associated with adverse env conditions
What is conjugation
transfer of genetic info bw bacterial cells via pili (only f+ bac)
-plasmids comonly transfered
What is transduction
process by which dna is transfered from one organsim to another (ex bacteriophage)
What is transformation
process in which the genetic makeup of a bacterial cell is changed by intro of free DNA from surrounding env.
