Protein synthesis

Why protein synthesisProteins do almost all of the work

in the cell (and organism). Six functions of proteinsControl of the number and type

of proteins is critical for maintaining homeostasis.

Understanding protein synthesis allows us to understand the most important homeostatic control system.

scaleNerve cells rarely undergo mitosis,

but require a large number of transport proteins to be produced.

You produce about 1,000,000 red blood cells per minute, each cell is stuffed full of hemoglobin proteins.

Beta cells in the pancreas have to produce insulin in large amounts rapidly when food/drink is taken in.

How is it controlled? What is found on chromosomes? What do genes do? How many genes do we have?How many different types of

proteins are found in your body?

Transcription elongation

RNA Polymerase moves along template strand.

RNA Polymerase makes RNA complementary copy of template strand of DNA.

DNA rewinds pushing off RNA strand

Transcription- terminationRNA Polymerase

reaches terminator and falls off.

DNA rewinds pushing the RNA strand completely off.

Translation initiationtRNA carrying MET joins with

mRNA and small ribosome subunit at AUG

Large ribosome subunit joins complex.

Translation elongation2nd tRNA brings

in next amino acid.

Large ribosome subunit joins amino acids.

Ribosome moves over 1 codon.

1st tRNA falls off.

Next tRNA comes in.

Translation- terminationWhen ribosome reaches stop

codon, a protein called release factor binds.

Release factor breaks up complex, releasing polypeptide.

RNA processing

RNA processingOccurs after transcription, before

the mRNA leaves the nucleus. Proteins cut out the introns and

put the exons back together. Exons can be rearranged to

produce different proteins from the same gene.

RNA processingHow does the mRNA know where to

go?◦Proteins add a cap to the beginning of

the mRNA. ◦Cap tells whether mRNA goes to free

ribosome in cytoplasm or Rough ERHow many proteins can be made

from 1 mRNA strand? ◦Proteins add a tail to the mRNA, the

longer the tail, the more proteins can be made from it.

mutations

Genetic code chart