7. Molecular Genetics Flashcards
DNA goes from
5’ to 3’
replication
helicase unwinds dna forming a replication fork
- SSBs keep it open
- Topoisomerase decreases tension
- DNA pol moves from 3’ to 5’ making strand
- makes the lagging strand using primase fragments (DNA ligase connects and then DNA pol I changes to DNA)
DNA pol functions
pol 3 replicates but can also check via exonuclease
- pol I breaks down fragments
telomere replication
telomerase adds elongation to end so it doesn’t degrade
protein synthesis
- AA’s are redundant
- mRNA has 64 possible codons
- tRNA has a clover shape with h bonds (tiny abundance)
- rRNA (rich abundance) is the DNA being transcribed with the mRNA (merger abundance) bound as well as the tRNA
transcription
- RNA pol binds to promoter region (in eukaryote is tata box, prokarya is Pribnow box)
- only one strand is transcribed, which is the temple antisense DNA trand, while the other is the CODing/ sense strand
- AAA coding strand is end
rna has greater error than
dna
mRNA processing
5’ cap, poly a tail, introns spliced out
translation
- GTP as energy
- small ribosome attaches to 5’ end, MET attaches to AUG
- elongation then A site releases MET in E site. this then moves in translocation.
- termination is reaching stop codon UAG, UAA, UGA
- folding using chaperone proteins
post translation
may go to ER and secreted via Golgi
multiple ribosomes can attackh in
prokarya
bacteria start codon
formylmethionine
silent mutation
same codon
nonsense
new codon is stop codon
missense
codon is new amino acid
proofreading mech
- dna pol, mismatch repair for mismatched bases, or excision repair where damaged dna goes away (T dimers)
nucelosome
DNA around 8 bundles of histones
euchromatin
loosely bound dna to be transcribed
heterochromatin
tight DNA no transcribe
transposons
dna segments that jump around
pseudo genes
no longer code for anything
virus
DNA or RNA with protein capsid coat made from capsomeres and viral envelope (protein from host if it has one)
lytic cycle
virus penetrates host and then hijacks it to make new virus, then explode out of cell and infect other cells
DNA virus
dna forms new viral dna
rna virus
rna serves as mNA that is made into a protein
retrovirus
use reverse transcriptase to make DNA complete their na, which goes to lysogenic cycle
lysogenic
viral DNA is incorporated into DNA of host cell. can be dormant (provirus or prophage)
prions
misfolded proteins that cause others to misfold
viroids
smaller than virus RNA that infect plants
binary fission
chromosome replicates, cell divides (bacteria!)
plasmids
short dna that is outside chromosome (not essential)
episomes
plasmids that incorporate into bacterial chromosome
conjugation
donor produces pills, connects ot recipient, sends chromosome and then it recombines.
transduction
DNA is given by virus. done in lytic cycle when bacterial dna goes in place of viral dna
operon in prokaryotes
has
- promoterL RNA pol attaches
- operator: region that blocks rna pol
- genes: DNA
- regulatory genes: produce repressor or activator proteins that affect promoter region
lac operon
breakdown of glucose. when lactose available, lactose removes repressor and now can make enzyme.
low glucose is cAMP?
high cAMP levels
cAMP?
binds to cap binding site of promoter region. and thus gives better transcription
if lactose and glucose are high
then no operon production for lactase. body prefers glucose digestion
typ operon
enzyme for tryptophan synth. tryptophan itself binds to activate repressor, and blocks rna pol
repressible enzymes
when genes sto[ making enzymes in presence of an active repressor
constitutive genes
constantly expressed
regulation allowing cell specific stuff
using activators can make different cells by turning off certain segments
methylation of histores
tighter packing so no transcription
acetylation
uncoiling of chromosomes so transcription proceeds
RNA interference
micro and short interfering (miRNA or siRNA) RNA can block translation too.
- RNA interference is specifically siRNA blocking
