unit 2 exam Flashcards
where are bases located in DNA?
on the inside of the helix
B-form DNA
asymmetric, major and minor grooves, major groove accessible to proteins
Z-form
left handed helix, Hoogstein base pairs, one base in syn formation and one in anti
A-form
RNA-RNA or RNA-DNA interactions
difference between RNA and DNA sugar
RNA has a 2’ OH and DNA does not
what affects melting points of DNA?
longer DNA fragment = higher Tm
more A-T pairs, less C-G pairs = lower Tm
what does topoisomerase do?
cuts DNA to decrease Lk
key points of topology
Lk = Tw + Wr
natural twist = #bp/10.4
Tw = -Wr is most favorable
highly supercoiled DNA moves faster in gel electrophoresis
key points of acetylation
added by enzymes called Histone Acetyl Transferases (HATs)
makes DNA more accessible
stimulates transcription
reversible!
process for compacting DNA
DNA –wound around histone–> nucleosome –compressed to 30nm fiber–> chromosome
heterochromatin
inaccessible
histone methylation
euchromatin
accessible
histone acetylation
purpose of S-methylcytosine
silences gene expression
how is the STOP codon different from other codons
it is recognized by a protein rather than W-C-F base pairing with tRNA
what catalyzes peptide bond formation in rRNA
the protein component
what is being copied in RNA translation?
The coding strand
what is necessary for group 1 introns to carry out splicing functions
a free guanosine nucleotide cofactor to perform first step of splicing
function of DNA pol III
workhorse polymerase
function of DNA pol I
handyperson polymerase
what is the opening enzyme?
helicase