BIOL 415 - Chapter 8 Protein Synthesis

codon

The basic unit of the genetic code; 3 nucleotides; one of the 64 nucleotide triplets that code for an amino acid or stop sequence

mRNA

An RNA molecule that serves as a template for protein synthesis; RNA poly ll makes it; made in the nucleus

rRNA

The RNA component of ribosomes; made in the nucleus

tRNA

An RNA molecule that functions as an adaptor between amino acids and mRNA during protein synthesis.

anticodon

The nucleotide sequence of transfer RNA that forms complementary base pairs with a codon sequence on messenger RNA

3’ CCA

Ribosome

A particle composed of RNA and proteins that is the site of protein synthesis

small subunit

40 S in eukaryotes

large subunit

60 S in eukaryotes

Aminoacyl tRNA synthetases

three stages of translation

initiation, elongation, termination

3 binding sites of translation

aminoacyl, peptidyl, exit

where does methionyl tRNA bind to in translation?

p site

cap-dependent translation

a eukaryotic cell uses the 5’ cap (m7G) of mRNA to recruit the ribosome and initiate protein synthesis. The 5’ cap is recognized by eIF4E.

What is the relationship between eIF4E and eIF4G

when eIF4G and eIF4E are bound together in cap-dependent, the eIF4G changes the conformation/shape of eIF4E do that it can bind to the methyl cap

cap-independent translation

IRES

internal ribosome entry sites

what initiation factors are involved in cap-independent translation

eIF4G and eIF4A bind to the IRES, then bring in the complex to start scanning

what forms the ternary complex

GTP, eIF2, methionyl tRNA

elongation stop codons

UAA, UAG, UGA

release factors eRFs

recognize stop codons and disperse all units

what is a GAP

GTPase Activating Protein

what does a GAP do

encourages a G Protein to change shape and hydrolyze its GTP to GDP

eIF2

brings the initiator Met tRNA to the P site

what is GEF

guanine-nucleotide exchange factor

what is the function of GEF

a protein that activates a GTPase by helping it exchange GDP for GTP

what kind of activity does an activity G Prptein have?

intrinsic GTPase activity

eukaryotic initiation factors

eIF2, eIF2B, eIF4E, eIF4G

eukaryotic elongation factors

eEf1α, eEf1βγ, eEF2

eEF1a function

a GTP-binding elongation factor that delivers aminoacyl-tRNAs to the ribosome's A site during protein synthesis

eEF1By function

it is a GEF for eEF1a because it causes the GDP to phosphorylate to GTP. The eEF1a is now an active G-Protein and can go grab another amino acid for elongation.

polysomes

multiple ribosomes can translate mRNA simultaneously

translational regulation of ferritin when iron is scarce

IRP

iron binding protein

IRE

iron response element