Translation and Mutation

proteins

polymers of amino acids

protein functions

enzymes, transporters, communication, build cell structures

a protein’s function

is determined by its structure

primary structure

linear sequence of amino acids in a protein

amino acids

covalently connected by peptide bonds through carboxyl groups

peptides

are short amino acid chains

polypeptides

are long chains of amino acids

amino acids are coded for

on mRNA

multiple codons

for each amino acid

each amino acid

has its own tRNA determined by mRNA sequence

codon on mRNA binds to

the anticodon on tRNA

before translation begins

ribosome assembles

shine-Dalgarno sequence

ribosome binds here on mRNA

large subunit of ribosome 

50S

small subunit of ribosome

30S

large subunit contains

three sites for tRNA

tRNAs carrying amino acids

fit into sites on large subunit

A site of large subunit

amino acids arrive here

P site of large subunit

peptides are made here, where growing polypeptide is found

ribosomes have

peptidyl transferase activity carried out by rRNA that act as ribozymes

E site

where empty tRNA exits the ribosome

methionine

start codon

stop codons

end translation

point mutation

single nucleotide is switched

silent mutation

mutation that has no affect

missense mutation

mutation that changes amino acid sequence

nonsense mutation

mutation that stops translation

proofreads

rn polymerase cannot correct mistakes

frameshift mutation

whole base is inserted or removed

thymine dimers

cause dna polymerase to stall, occur when exposed to UV radiation, can be repaired or cut out

mutagens

ionizing radiation, reactive oxygen species, intercalating agents