Ch. 17 from gene to protein

eukaryote have a RNA processing step

whats the difference between making of a trait in a eukaryotic cell vs a bacterial cell

transcription

the making of RNA from DNA

RNA polymerase

enzyme that makes an RNA copy of a gene by reading the complementary DNA strand

false

RNA polymerase require a primer to make RNA

tells RNA polymerase where to start and which direction

what is the purpose of the promoter

true

the promoter does not get translated into RNA

exon

RNA that is spliced together and exits the nucleus

introns

RNA that stays in the nucleus

upstream

what direction from the promoter is RNA going to replicate?

template strand

strand that RNA polymerase reads

coding stranding (nontemplate)

looks like mRNA except for when T turn into U

3'-5’

what direction does RNA polymerase read?

5’-3’

what direction does RNA polymerase write?

transcription initiation

RNA polymerase and transcription factors binds to promoter; first step of transcription

TATA box

beginning of promoter, made up of TATAAAA

TATA binding protein (TBP)

binds TATA box first, then other transcription factors form a complex around

transcription initiation complex

transcription factors interact with RNA polymerase to create a complex that unwinds DNA and RNA poly begins transcription

elongation

RNA polymerase begins synthesizing RNA

termination

RNA transcript is released from RNA polymerase

polyadenylation

what sequence signals termination?
this sequence is coded into RNA

endonuclease

binds to AAUAAA signal to RNA
cuts RNA 10-35 nucelotdies downstream of polyadenylation signal
release RNA from DNA and the RNA polymerase

5’ cap

consists of modified GTP (guanosine triphosphate)
put on while RNA is still being made

50-200 adenines

what is the 3’ cap of RNA made up of?
this is NOT encoded by the gene

protects the 5’ and 3’ end from degradation, aids in export of mRNA from nucleus, helps biding of mRNA to ribosomes in cytoplasm

what is the function of the 5’ and 3’ cap?

less expression of the gene because it’s degraded, not exported from nucleus, and not assisted with ribosome binding

what would happen if you don’t have 5’ or 3’ cap?

RNA splicing

the process of removing introns and splicing together exons

spliceosome complex

what is RNA splicing catalyzed by?

alternative splicing

the purpose of introns that allows production of multiple protein produce from a single gene is called?

translation

the process of making proteins from RNA

codons

3 nucleotides that makes up one amino acids

n^c = a

what’s the equation to find possible amino acids give the # of nucleotides and codon size? n = nucleotides, c = codon size, a = amino acids possible

universal, redundant, unambiguous, and nonoverlapping

what are the features of genetic code?

universal

genetic code is the same in all organisms, making it what?

redundant

some amino acids are encoded by several codons (ex: there are 3 codons that code for Leu)

unambiguous

one codon never encodes multiple amino acids

nonoverlapping

each base is part of only one codon

methionine

start codon name where translation starts

5’ untranslated region (5’ UTR)

what is the name of the section that occurs before the start codon?

stop codon

where is mRNA no longer read?

start gets translated to methionine while stop codon is NOT translated

does the start codon get translated? does the stop codon get translated?

3’ UTR

untranslated region after the stop codon

tRNA

read language of mRNA codon through anticodons and bind a specific amino acid through 3’ end

anticodons

what does tRNA use to read mRNA codons?

3’ end of tRNA

the amino acid is attached to where of the tRNA?

aminoacyl-tRNA synthetase

enzyme that binds amino acid to a tRNA; there’s 20 different type, one per amino acid

specific to amino acids

is aminoacyl-tRNA synthetase specific to the number of tRNA or specific to number of animno acids?

last base of anticodon binds weakly to codon; wobble pairing

there are 64 codons but only 45 tRNA, how can it cover all 64 codons?

2/3 RNA & 1/3 protein

what is ribosome consists of?

mRNA, A site, P site, E site

what are the 4 binding sites in a ribosome?

once bound to mRNA

when do the two subunits come together?

A site (aminoacyl-tRNA site)

accepts incoming tRNA

P site (peptidyl-tRNA site)

holds tRNA with growing polypeptide chain

E site (exit site)

site from which empty tRNA exits

initiation, elongation, termination

what are the stages of translation

translation initiation

small subunit binds to 5’ end of mRNA, scans for first AUG
anticodon of intiator tRNA base pairs with start codon (carry methionine)
large ribosomal subunit then binds (dependent on GTP)
initiator tRNA sits in P site

initiator tRNA

anticodon of mRNA start codon that carries methionine and sits at P site

codon recognition

anticodon of incoming tRNA binds to A site
anticodon of tRNA H-bonds with codon of mRNA
P-site contains growing polypeptide chain

peptide bond formation

peptide bond forms between polypeptide and new amino acid
catalyzed by rRNA in large subunit of ribosome
results in transfer of polypeptide to incoming tRNA

translocation

ribosome translocate on the mRNA
P-site now contains tRNA with growing polypeptide
E-site allows the ‘empty’ tRNA to leave
cycle continues as next tRNA binds to empty A site
requires GTP

translation termination

occurs at stop codon
no tRNAs but codon are bound by release factors
hydrolyze bond linking polypeptide and tRNA
ribosome, mRNA, and polypeptide dissociate

polysomes

a string of ribosomes on a single mRNA simultaneously synthesizing polypeptide

increase speed of polypeptide production

what’s the purpose of having multiple ribosomes on one mRNA?

transcription and translation are coupled

what happens in prokaryotes that doesn’t happen in eukaryotes ?

while RNA is bring made from a strand of DNA, that RNA is also being translated to polypeptide

what does it mean that transcription and translation is coupled?

bacterial components to transcribe/translate are slightly different from human ribosomes

how come antibiotics affect bacteria and not human cells?

point mutation

a single nucleotide change (ex: sickle cell disease

nucleotide pair substitution

replacement of one nucleotide with another

silence, missense, nonsense

what ate 3 types of nucleotide pair substitution?

silent substitution

no change in amino acid, synonymous substitution, no impact

missense substitution

change in amino acid, nonsynonymous

nonsense substitution

early stop codon (truncated protein)

insertion and deletion

insertion or deletion of nucleotides

frameshift

occurs in a deletion/insertion when the following base pairs are shifted over

extensive missense and nonsense, not in multiple of 3

what type of insertion / deletion leads to a frame shift? and how many nucleotides are deleted?

multiples of 3 result in missing or extra amino acids

how many nucleotide must be inserted/deleted to have no frameshift? this results in what?

cause drastic change to protein

why is frameshift harmful?