molecular genetics Flashcards
central dogma
DNA –> RNA –> protein
- transcription and translation
hershey-chase experiment
radiolabeled sulfur and phosphorus to distinguish where genetic info was (protein vs nucleic acids)
- result was radiolabeled phoshporus which is in dna not protein
reverse transcriptase
allows dna to be transcribed from rna
- retroviruses
- special kind of dna polymerase that operates with rna template
codon
3 dna nucleotides that code for an amino acid
4^3 = 64 combinations
degeneracy
multiple codons can make the same amino acid
- increase resistance to error
wobble position
provide protection against mutation in the final nucleotide of a codon. most codons are defined by the first two nucleotides
stop codons
UGA, UAG, UAA
start codon
AUG (met)
watson and crick model of dna
dna is a double helix of antiparallel strands with a sugar phsophate backbone
- complimentary basepairing
- interior stabilized by h bonds between bases and hydrophobic interactions between stacked bases
base stacking
arrangement of nucleotide nitrogenous bases that allow for hydrophobic interactions`
compliementary dna strands
are complimentary and antiparallel (be aware of directionality when looking at question wording)
how is dna organized in eukaryotes
linear chromosomes in the nucleus
autosomes
22 chromosomes in humans that are somatic cells and have two copies each. 1 maternal and 1 paternal
sex chromosomes
two each
female XX
male XY
how is the massive content of dna squeezed into chromosomes
histones and chromatin
histones
proteins that are wound around dna with subproteins: h1 h2A h2B H3 H4
core: two dimers ofh2a and h2b and a tetramer of h4 and h3
h1: linking unit
nucleosomes
dna-histone complex
- beads on a string
chromatin
structure formed by nucleosomes (dna and histones)
euchromatin
loose configuration that allows dna to be easily transcribed
- during interphase (allows for transcription)
heterochromatin
tighly coiled dense form of chromatin that is visible during CELL DIVISION
how do histones and dna interact
charge driven interactions
- histones are positive and dna is negative
acetylation of histones
reduce their positive charge, and loosen binding on dna allowing for an increase in dna transcription
semiconservative replication
dna replication where end product is 1 original strand and one new strand
meselson-stahl experiment
experiment that distinguished between old and new dna
they grew radioactive N in e. coli and traced it
- found that dna is semi-conservative