chapter 7 Flashcards
3 key properties of genetic material
- information content (encode proteins and DNA)
- faithful replication
- infrequent mutations
when watson and crick collabed they found out
- genes encode specific traits and proteins
- genes are carried on chromosome
- DNA is the genetic material
griffith experiment
experimented with mice, DNA is the transforming principle
avery, macleod, mccarty
more dead mice, but used enzymes to break down other things like lipids and polysachs to make SURE dna was that girl
hershey-chase
T2 phage injects bad DNA (not proteins as originally thought) into victim (e.coli) so it reproduces it.
4 nucleotides
A, T, G, C or in fancy words dAMP, dTMP, dGMP, dCMP
chagraffs rule
total pyrimidines = total purines
pyrimidine bases are
T and C
purine bases are
A and G
what is the visual difference between pyrimidines and purines
pyrimidine is single ring and purine is double ring
What are the nucleotide pairs
AT
GC
double helix structure
looks like spiral staircase, each strand is a nucleotide chain held together by sugar phosphate backbone
phosphodiester bonds
bridge between 2 oxygens and 2 adjacent sugar residues
5’ to 3’
polarity
strands are assembled in a directional manner (5’ to 3’)
how many hydrogen bonds hold together A and T
2
how many hydrogen bonds hold together G and C
3
semiconservative
one old strand (template) and one new strand
other options (conservative and dispersive)
conservative: olds together and news together
dispersive: chunks are swapped
DNA strands bind where they are ______
isodense (have similar density)
DNA polymerase III
synthesizes DNA (only in 5’ to 3’ direction)
DNA polymerase III can only add nucleotides to the ___ end of the existing strand
3’
leading strand
synthesized continuously (end is 3’ so it can just go down the line)
lagging strand
synthesized discontinuously (end is 5’ so it has to do it in chunks using RNA primers)
primase
synthesizes RNA primers so DNA polymerase III has somewhere to attach
where are RNA primers?
along the lagging strand and at the beginning of the leading strand
polymerase I
degrades RNA primer and fills gaps (okazaki fragments) with DNA
what direction does polymerase I add nucleotides in
5’ to 3’ direction
ligase
repairs the nick and seals the strand
replisome
complex of proteins for DNA replication
helicases
melt duplex (breaks hydrogen bonds to split the strand)
single strand binding proteins
prevent reformation of duplex
topoisomerase
relax supercoiling
proofreading
polymerase I and III use 3’ to 5’ exonuclease activity to excise mismatches base pairs
origin of replication
fixed place where replication starts (common in e.coli, replication then branches out in both directions)
replication bubble
chunk that is being replicated (where template is unwound and strands are apart)
replication fork
where DNA is unwound
telomeres
repetitive buffer at the end of DNA strand (100s of nonsense nucleotides so info isn’t lost)
telomorase
ribonucleoprotein that puts telomeres
elongation
extends the 3’ end with telomeres after each replication
translocation
shifts telomere down
