microbio ch 8

ligase

attaches DNA okazaki fragments together

primase

makes the primer which indicates to DNA polymerase where to start building

polymerase

replicates DNA to start building new strands

helicase

separates DNA strands for replication

origin

where DNA replication starts

SSB proteins

binds to DNA strands to keep them separated during replication

topoismerase (gyrase)

binds to replication fork to relieve strain on the DNA during separation and prevent supercoiling

start codon

AUG

silent mutation

base substitution that may change the codon but not the amino acid/protein

missense mutation

base substitution that changes the amino acid and may alter the protein

nonsense mutation

base substitution that results in a nonsense codon (regular codon replaced with stop codon)

frameshift mutation

mutation that involves the insertion or deletion of a nucleotide in the DNA sequence, resulting in a completely different amino acid

stop codon

UAA, UGA, UAG

mutagens

factors that induce mutations, like UV, chemicals, and radiation

central dogma

DNA is transcribed into RNA which is translated into proteins

promoter

a sequence of DNA on an operon that indicates to RNA polymerase where the operator is

operator

a region of DNA on an operon where RNA polymerase can bind and start transcription

repressor

can bind to the operator on an operon to prevent RNA polymerase from binding and inhibit transcription

lac operon - induction

when lactose is present, lactose binds to the repressor which causes a conformation change and forces the repressor to unbind from the operator. this allows RNA polymerase to bind to the operator and begin transcription/protein production

lac operon - repressor

when lactose is absent, the repressor binds to the operon and prevents RNA polymerase from transcribing mRNA which inhibits protein production

where does translation occur in eukaryotes and prokaryotes

eukaryotes: nucleus
prokaryotes: cytosol

terminator

region on an operon that indicates to RNA polymerase to stop transcription

lagging strand

DNA replication occurs in the opposite direction of the replication fork and DNA polymerase can only work in fragments (discontinuous)

leading strand

DNA replication occurs continuously in the same direction as the replication fork

why are replicated DNA strands considered semi-conservative?

each copy of DNA made from replication consists of one original strand and one new strand