Chapter 8 Microbial Genetics Pt2 Flashcards
What is gene regulation, why is it important
Cells turn enzymes on and off to control metabolism; prevents synthesis of unneeded enzymes
Save energy
What are constitutive genes and what % of all genes are constitutive
Their products are constantly produced at a fixed rate (60-80% of genes) always turned on
Genes that code for products cell doesn’t always need; not always turned on
Inducible genes
Genes that are normally on, which are usually the constitutive genes, are called
Repressible genes
Repression vs induction (to control gene regulation)
Repression: inhibits gene expression and decreases synthesis of enzymes
Induction: turns on transcription of gene(s)
What is a silent mutation
Doesn’t result in change of amino acid
2 different kinds of base substitution mutations
Missense- results in change of 1 amino acid
Nonsense- results in change of 1 of stop codons ( May create a stop codon in middle of mRNA)
Which base substitution is almost always lethal
Nonsense mutation
A frame shift mutation is what kind mutation
Base insertion or deletion
What Ames test determines
Whether a substance was mutanegenic, and therefore carcinogenic
How come when a known mutagen, like salmonella that cannot produce histidine, is added to an unknown mutagen grows (even without histidine present)
This means that the unknown mutagen is mutangenic, it caused mutations in the salmonella so it could begin producing histidine
3 natural types of recombination in bacteria
Transformation , conjugation, transduction
What is transformation
Genes transferred from one bacteria to another (pick up from environment) incorporate into own genome
The experiment that proved transformation also proved that
DNA is the genetic material
In the experiment that proved transformation, how come the 4th mouse died? Even tho it was only injected w living nonencapsulated bacteria and heat killed encapsulated bacteria
While only live encapsulated bacteria are able to evade the immune system and kill the mouse, the killed encapsulated bacteria transformed capsule forming genes to the live unencapsulated bacteria
What is conjugation
Recombination via a sex pili or making bridge (physical connections )
Which cell is the recipient cell during conjugation (F pos or neg)
F- (becomes F+)
During conjugation, the Plasmid contained within the F+ cell is also called
The F factor
When the F factor becomes integrated into the chromosome of an F+ cell it becomes a
Hfr cell (High frequency of recombination cell)
What is a bacteriophage
A virus that infects bacteria
How transduction works
1) bacteriophage injects DNA into cell and takes over host
2) new phages begin forming inside host, during assembly pieces of bacterial DNA are packaged into phage capsids
3) when host lyses, releases phages (some only have bacteria DNA rather than viral)
4) infect other hosts and incorporated into chromosome
