Genetic Code and Translation

prokaryotic gene expression is

polycistronic mRNA and no introns

Eukaryotic Gene expression is

monocistronic and full of introns

Amino acids are joined together by

peptide bonds

What is the primary strcuture of an amino acid

amino acid sequnce

Francis crick proposed

non-overlapping code

Brenner and Crick established

codon consited of 3 non-overlapping nucleotides

triplet code

3 reading frames/strand

nirenberg and matthaei

first to determine that a specific RNA sequence coded for a specific amino acid

The coding dictionary is

unambigous, degenerate, almost universal

due to wobble

a single tRNA can pair with more than one codon in mMRNA

How many codons code for amino acids

61

How many tRNA molecule are there

31-41

Inosine can pair with

uracil, cytosine, and adenine

Translation is the process of

mRNA to protein sequence

What is step one of translation

charging the tRNA

What is step two of translation

initiation

What is step three of translation

elongation

What is step four of translation

termination

aminoacyl synthetase for each amino acid can

recognize all tRNAs for that amino acid

the amino acid’s carboxyl end is joined to the

3’ end of the tRNA

the 5’ untranslated region of mRNA contains

the shine dalgarno sequnece

The shine dalgarno sequence is important for

ribosomal binding and is 7 nts upstream from the start of translation

polycistonic mRNA

1 RNA molecule is produced but it contains the information for translation into more than one gene product

The shine-dalgarno region of mRNA pairs with the

16s rRNA sequence in the small ribsomal unit

what three sites on a ribosome can hold tRNAs

A,P,E

A site

aminoacyl: new tRNA comes in

P site

peptidyl: bond forms

E site

spent tRNA EXITS ribsome

23s rRNA in the large subunit acts as a

ribozyme to form peptide bond between amino acids

The large subunit acting as a riboenzyme is called

peptidyl transferase activity

translocation of ribsome requires

1. gtp

2. elongation factor

Termination

stop codon arrives at A site, release factor binds at stop codon, protein is realeased and GTP allows other parts to dissacoaite

Polysomes

multiple ribosomes translating the same mRNA simultaneously

Eukaryotic translation requires

a cap on mRNA, AUG codon, Kozak sequnce, tail on mRNA