genetics test 3 part 1

helicase

unzips DNA by breaking hydrogen bonds

single strand binding

keep separated DNA strands apart and prevent rejoining

primase

makes short RNA primers to give DNA polymerase a starting point

DNA polymerase III

main bacterial DNA building enzyme, adds nucleotides to build 5’ to 3’

DNA polymerase I

removes RNA primers using exonuclease activity and replaces them with DNA

DNA ligase

seals break in the sugar phosphate backbone forming bonds

okazaki fragments

short DNA fragments made on lagging strands

RNA primer

short RNA starter that provides a free 3’ OH group

phosphodiester bonds

covalent bonds connecting nucleotides in the backbone

exonuclease

removes nucleotides from an end of a nucleic acid

diphosphate

released when DNA triphosphate is incorporated

chargaff’s rules

total purines = total pyrimidines

leading

continuous

lagging

fragments

wobble hypothesis

1 tRNA can read multiple similar codons

griffith experiment

some heritable substance transformed R bacteria into S (transformation)

Avery, MacLeod, and McCarty experiment

DNA is the transforming genetic material

hershey and chase experiment

DNA carries genetic instructions for viruses

RNA polymerase

builds RNA using DNA template, synthesizes RNA 5’ to 3’

sigma factor

helps bacterial RNA polymerase recognize promotor

rho factor

protein that terminates transcription by catching RNA polymerase and releasing the RNA transcript

shine-dalgarno sequence

ribosome binding sequence in mRNA that positions the start codon

fMet-tRNA

initiator tRNA carrying formylmethionine, recognizes the start codon

GTP

supplies energy for key steps of initiation

order of translation

initiation, elongation, peptide bond, translocation, termination

depurination

base disappears

deamination

amino group disappears

tautomeric shift

base temporarily changes form

lacZ

galactosidase

lacY

permease

lacA

transacetylase

low glucose

cAMP rises and binds CAP

high glucose

cAMP falls and CAP binds DNA less effectively