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
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