chapter 6; translation Flashcards
describe the structure of aa
-R group: specific for each aa, can be acidic, basic, neutral, polar, nonpolar
-amino group: NH2
-carboxyl: COOH
what is a polypeptide and the type of bonds it has?
chain of aa
-formed by peptide bonds between carboxyl group and amino group
describe determinants of order
1.DNA sequence
2.RNA message (transcription)
3. order of protein (made on ribsome complex)
4. shape
-structural
-enzymatic: changes shape
what are the structures of proteins?
-primary
-secondary
-tertiary
-quaternary
a.a sequence
primary structure
folding and twisting of a single polypeptide chain, H-O bonds in the polypeptide backbone.
-alpha helix: right handed coil
-beta pleated sheet: two or more chains stacked
secondary structure
tertiary structure
3D folding, interactions between R groups, disulfide bonds, H bonds, ionic bonds, hydrophobic interactions.
quaternary structure
two or more tertiary structures, multisubunits
describe the tRNA structure of
-cloverleaf
-5-3 antiparallel
-acceptor stem: ends in ACC-3’
-anticodon: vary
characteristics of the code system
-triplet code
-table: almost universal
-start codon: AUG
-stop codon:UAA, UAG, UGA
-start and stop codons help define ORFS
what enzyme “charges” a tRNA
aminoacyl-tRNA synthase
give the steps of the charging process of tRNA
- aa and ATP bind to enzyme
- hydrolysis: AMP, then joins a.a
- tRNA binds to enzyme, transfers aa, AMP displaced
describe ribosomes
-2 subunits, one large and one small
-contain rRNA and ribosomal proteins
-eukaryotic: 60s and 40s
-s represents suedberg units
-mRNA passes through small unit
what are the structures needed for initiation in translation? (scanning model)
- eIF-3 and 40s ribosome subunit
-eIF-2 with charged tRNA
-eIF-4 on RNA 5’ cap
after scanning model, follows
-eIF-1 removes 2 and 3
-eIF-5 brings large subunit 60s.
elongation is triggered by
poly-A binding proteins hitting complex
A site:
-aminoacyl, where an incoming aminoacyl- tRNA bind
P site:
the peptidyl site, tRNA carrying the growing peptide is located
E site:
exit site; where tRNA binds on its path from P site to leaving the ribosome
EF-TU function
brings one tRNA after another with correct anticodon
what carries out the formation of peptide bonds between aa. aa releases from tRNA, tRNA then leaves P site
peptidyl transferase
EF-G function
shifts ribosome
codon move to the _____ side
left
what triggers termination
encounter of UAA codon, eukaryotes do not have anticodon for it
describe the termination process (translation)
RF-1 ( on A site) and RF-3 ( protein complex) bind and aa rips of tRNA.
signal peptide
specific protein sequence
signal recognition particle (SRP)
bind to SRP receptor and is located on the ribosome
SRP receptor
on ER, binds with SRP
signal peptide fills into ER, once inside it is ________
modified
if a protein is made in the ER: it ends up in
membrane, surface protein, or outside the cell membrane
if a protein is made in the cytoplasm
it stays in the cyto
