APBIO 5.5

gene expression

process in which DNA leads protein synthesis

DNA codes or traits how?

by controlling which proteins are synthesized

one = one

gene, polypeptide

mRNA codons are read in what direction

5’ to 3’ direction

one codon specifies what

one of the 20 amino acids

start/met

AUG

stop

UGA UAA UAG

when manually transcribing mRNA

only start at the start codon and make 3s for codons

genetic code is

nearly universal

Transcription

Initiation, Elongation, Termination

Promoter

(initiation) signal start of RNA synthesis in Initiation

Transcription factors

(initiation) helps RNA polymerase and promoter bind to start transcription

transcription initiation complex

(initiation) transcription factors ad RNA polymerase II bound to promoter

TATA box

(initiation) promoter that is a starting point for the RNA polymerase to bind

Rate of untwisting via RNA polymerase

(elongation) 10-20 bases at a time

several RNA polymerases

(elongation) can transcribe one gene at the same time

bacterial termination

(termination) polymerase stops at terminator

eukaryotic termination

(termination) transcription does not stop until it reaches polyadenylation signal. Then polymerase falls off

Polyadenylation signal

AAUAAA

pre-mRNA → mRNA

RNA splicing occurs, introns are removed and exons are binded together

introns

useless non-coding sections of DNA (have some info tho)

exons

normal sections of DNA that stay after transition from pre mRNA to mRNA

5’ cap ; poly-A tail

basically phosphate thing on sides of DNA ; on 3’ side … Function is to protect mRNA and help ribosomes attach to 5’ end

RNA splicing is done by what

spliceosomes or RNA ribozymes

alternative RNA splicing

allows for a gene to make 2+ polypeptides by making different combos with exon segments

RNA can function as an enzyme/ribozymes because

It can form a three- dimensional structure because of its ability to base pair with itself

Some bases in RNA contain functional groups

RNA may hydrogen-bond with other nucleic acid molecules

site P

tRNA starts here

site A

tRNA carries amino acid and adds it to polypeptide chain

E sit

exit, tRNA leaves ribosome

substitution mutation

replacement of nucleotides

addition/deletion

add or delete a nucleotide pair

silent mutation

codon is changed by codes for same amino acid/polypeptides

missense mutation (worst)

code for incorrect amino acid/polypeptide due to substitutions

nonsense mutation

codon is changed to be a stop codon usually cause nonfunction

frameshift mutation

3-codon pattern is messed up and everything else shifts aswell

mutagens

cause mutations in DNA

carcinogens

mutagens that cause cancer