genetics Flashcards
why are bacteria easy to study?
cheap, easy to keep as need only broth, large colony of clones, incubate 37 degrees, haploid
Lac Operon? and how does it work
gene cluster that codes for enzymes that breakdown lactose
repressor bind to operator blocking way for RNA polymerase. when lactose present, binds to repressor and so RNA polymerase can transcribe gene producing 3 enzymes?
3 enzymes from Lac Operon?
Beta glactosidase( breask down lactose), permease(transports lactose into cell) , transacetylase
What inhibits Lac Operon
if lots of glucose, it binds to the CAP that assists RNA polymerase so cannot transcribe gene
2 ways to modify chromatin so open to transcribe?
- Acetylation of lysine at N terminus of histone so DNA less in contact and can be accessed
- Methylation on cytosine add CH3 it swithces off genes
epigenetic change?
change that effect gene expression but not nucleotide sequence
Way to lyse cells?
repeat freeze thaw, mechanical e.g. pestle and mortar, chemical detergents to dissolve membrane
Different DNA gels for electrophoresis?
agar- 100-20,000 bps
polyacrilimide - 10-700 bps
What affects how quickly DNA moves in electrophoresis?
how long strands - smaller is faster
concentration of gel
how compact, supercoiled is faster than linear
Why is looking RNA better than DNA
all cells same DNA but only transcribe RNA that need
Sanger method?
denature to single strand by adding heat, aneal primers to template.
Add free nucleotides and DNA polymerase
Add terminators that lack OH at 3 prime
terminators are tagged
Restriction enzymes?
precise protein cutters for specific sites, from bacteria, cut dsDNA only, palindromic sequence only, leaving sticky ends
Polymerase chain reaction?
amplify small amounts of dna,
uses- detect infectious agent, reasearch, modify, make primers
2 to the power of number of cycles = fragment number
dentatue at 95 degrees, aneal primers at 55, elongate with free nucleotides at 72
