KH2 Flashcards
describe central dogma of biology
theory that DNA (heredity) leads to RNA leads to protein
this gives rise to physiology and development biology = organism form/function
describe langue analogy (central dogma)
DNA synthesis replication = making perfect copy (thymine)
RNA synthesis transcription = resetting in a different nucleotide font (using uracil)
protein synthesis translation = rewriting in a different language (nucleotide vs aa)
describe replication (biopolymer, template and enzyme)
DNA
DNA
DNA polymerase
describe transcription (biopolymer, template and enzyme)
RNA
DNA
RNA polymerase
describe translation (biopolymer, template and enzyme)
protein
mRNA
ribosome
describe most enzymes
most enzymes are proteins (includes DNA and RNA polymerase)
describe ribosomes (composition)
ribosome includes protein and RNA components - both contribute to enzymatic function
RNA = critical catalytic component
what is template of transcription
exposed DNA strand
specifies RNA sequence by watson crick base pairing
describe the reaction of transcription
nascent RNA chain antiparallel
chain growth at 3’ end by RNA polymerase
joins last nulceotide to new selected one
catalyzes attack of 3’OH on alpha phosphate of incoming rNTP
beta diphosphate dropped and released
describe the direct interaction of template with incoming monomer (rNTP)
watson crick base pairs
rNTPs diffuse randomly
RNA polymerase will only link incoming rNTP to growing chain if it is the right base
must have the correct base and polymerase can sense when the right one comes in
what is the sequence of RNA transcribed correspond to
the non template strand which is not used to make RNA
both the non template and the new RNA strands are complementary and antiparallel to the template DNA strand
*RNA has U instead of T tho
describe the transcription bubble
local unwinding of 2 turns ~ 20 bases of double stranded DNA
what happens in transcription bubble
template DNA strand exposed by local unwinding of duplex DNA by helicase associated with RNA polymerase
one is used as template strand and other is non template (which is pushed away)
does transcription bubble stay in same spot the whole time
nOOO IT moves along the DNA with the RNA polymerase
what happens after DNA is unwound in transcription bublle
original duplex DNA reforms behind RNA polymerase as it moves unidirectionally along DNA
this reforming duplex kicks out newly synthesized RNA strand
RNA strand exits through a channel in polymerase 5’ end first
describe bacterial RNA polymerase transcribing DNA
growing RNA chain is extruded through exit channel of the RNA polymerase
transient transcription bubble moves with the RNA polymerase to the right
describe starting of RNA polymerase
promoters (certain DNA sequence) facilitate the initial binding (recruit RNA polymerase) of RNA polymerase to DNA
describe stopping of RNA polymerase
certain DNA sequences destabilize the attachment of RNA polymerase to the DNA as it moves
RNA polymerase falls off the DNA and releases the completed RNA chain and RNA will be exported
name and describe the things DNA replication and transcription have in common = 6 similarities
template is DNA
DNA duplex unwound by helicase at initiation sites and exposes template (replication origins)
new strand synthesized 5’-3’ antiparallel to template *chain growth at 3’ end
monomers = NTPs
direct interaction between template DNA and incoming monomer
attack of 3’OH on alpha phosphate of incoming dNTP and beta diphosphate dropped (same chemistry)
name and describe how transcription differs (from DNA replication) ~ 5 things
monomers = rNTPs
start and stop sites on template
newly synthesized strand separates from template
only one of original DNA strands is template
start with one molecule of duplex DNA and end with one molecule of duplex DNA + RNA molecule
name and describe how DNA replication differs (from transcription) ~ 5 things
monomer = dNTPs
start sites but no stop sites (never stops)
newly synthesized DNA never separates from template strand - is there until next replication and then they are separated
both of original DNA strands serve as templates
start with one molecule duplex DNA and end with 2 molecules duplex DNA
what is protein synthesis
translation
nucleotides into amino acids
words = codons (mRNA sequence)
dictionary = protein sequence
describe codons - and possible sequences (gen)
4 nucleotides
20 aas
3 nucleotides = codon
4x4x4x = 64 possible codons
describe the genetic code table
dictionary of codons (3 nts) and their corresponding amino acids
64 entries for 64 possible codons
