Download Protein Synthesis Facts

Protein Synthesis Facts
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Each one of your somatic cells (all cells in the body that are not sexcells) has 46 DNA molecules. Each of your sex-cells has 23 DNA
molecules.
It takes a cell just a few hours for a cell to copy all of its DNA
This replication is achieved with very few errors (only about one per
billion nucleotides)
More than a dozen enzymes and other proteins participate in DNA
replication
DNA polymerases are the enzymes that catalyze the elongation of
new DNA at a replication fork (50 nucleotides per second in human
cells)
Deoxyribose is the energy source for DNA. Ribose is the energy
source for RNA.
Ligase and Primase are the other two enzymes which catalyze DNA
replication
Translation (Building a Polypeptide)
- There are three stages in translation, and the synthesis of a
polypeptide chain (Protein)
- All three stages require enzymes that aid RNA in the translation
process
- The three stages are:
o Chain initiation
o Chain elongation
o Chain termination
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Chain Initiation
o mRNA are brought together
o AUG or TATA are the initiation codons, where translocation
actually begins
o Proteins called initiation factors bring mRNA, and initiator
tRNA together
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Chain Elongation
o Amino acids are added one by one to the initial amino acid
o Cycle takes only 60 milliseconds and is repeated as each amino
acid is added to the chain until the polypeptide is completed
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Chain Termination
o UAA, UAG, and UGA act as signals to stop translocation
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a protein called a release factor binds directly to the termination
codon
the release factor causes the ribosome to add a H2O molecule instead
of an amino acid to the polypeptide chain
this hydolysis frees the polypeptide from the ribosome. The ribosome
then separates into its small and large subunits
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Mutations
- occur as a change in the normal base sequence
- environmental factors may cause mistakes/mutations (such as
radiation (Ex: X-Rays, sun), high temperature (Ex: on male sex-cells),
or chemicals (Ex: Round-Up))
- mistakes that occur in somatic cells (all cells in the body that are not
sex-cells) of an organism do not affect later generations because only
sex-cells are involved in passing genetic information to offspring
- mistakes/mutations in the genetic code can sometimes be good and
sometimes be bad for an organism (ex: mutation that makes a
giraffe’s neck longer – reach higher or, mutation that causes cancer
cells)