Download Ribosomes and The Golgi Apparatus

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Ribosomes and The Golgi
Apparatus
Overview: Ribosomes
 Ribosomes read strands of
mRNA and use those
directions to make a protein
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Specifically every three bases
codes for an amino acid.
The three bases that are grouped
together are called a codon
Each codon that enters the
ribosome stands for a different
amino acid
Overview
 The ribosome moves along the
strand of RNA
 Each time it reads a codon, a
tRNA (transfer RNA) molecule
brings over the matching
amino acid.
 The ribosome attaches each
amino acid creating a chain of
amino acids (polypeptide)
 Once the polypeptide folds up
it creates a protein.
Amino Acid
Protein Synthesis: Translation
 Two parts of the ribosome, top and bottom, clamp
onto a piece of mRNA on the rough endoplasmic
reticulum
A base
U base
G base
C base
Protein Synthesis: Translation
 The ribosome moves along the mRNA until it
reaches a start codon (group of three bases that tells
the ribosome to start making a protein)
 The start codon is always A-U-G
A base
U base
G base
C base
Protein Synthesis: Translation
 The ribosome moves along the mRNA to the next
codon which codes for a specific amino acid.
Tyrosine
A base
U base
G base
C base
Protein Synthesis: Translation
 When the ribosome moves over again a tRNA brings
over the correct amino acid. It knows which amino
acid is correct because it has an anti-codon on its base
that is complimentary to the one on the mRNA
Tyr
A base
U base
G base
C base
Arginine
Protein Synthesis: Translation
 The ribosome moves to the next codon. This allows the
next amino acid to be brought over. The first amino
acid attaches to the next one in line before the tRNA
leaves the ribosome.
Tyr
A base
U base
G base
C base
Arg
Leucine
Protein Synthesis: Translation
 This process of adding amino acids to the chain
continues until the ribosome encounters a stop codon.
Tyr
Arg
A base
Leu
Val Met
Arg His
Val
U base
G base
C base
http://www.youtube.com/watch?v=5bLEDd-PSTQ&feature=related
STOP!!!
Over view: Golgi Body
 The golgi apparatus adds carbohydrates and lipids to
the outsides of the proteins and then packages them up
to leave the cell.
 The carbohydrates and
lipids act like an
address on a piece of
mail. They bind only
to specific cells.
http://www.youtube.com/watch?v=qF8hK0HtB1M
Protein Synthesis:
Finishing Touches
 Proteins when finished
being made by ribosomes
on the E.R. break off in
transport vesicles (made
of E.R. membrane) and
travel to the golgi
apparatus.
 A vesicle is a membrane
bound storage unit like a
vacuole, but it is meant
for transporting
molecules around the cell
Protein Synthesis: Finishing Touches
 The membrane of the
transport vesicle and
golgi apparatus join
releasing the protein
into the cis face
(receiving end) of the
golgi apparatus.
Protein Synthesis:
Finishing Touches
 As the protein moves
through the apparatus,
lipids and
carbohydrates are
added to it.
 More and more are
added as the protein
travels through the
different layers.
 Remember these
specify which cells the
proteins should enter
Protein Synthesis:
Finishing Touches
 When the finished
protein enters the
trans face (exiting
end) of the gogli
apparatus, it is once
again surrounded in
membrane which
will act as a
secretory vesicle (it
secretes the protein
from the cell).
Protein Synthesis:
Finishing Touches
 The secretory vesicle
with the finished
protein travels to the
cell membrane.
 The cell membrane and
vesicle membrane fuse
releasing the protein
outside of the cell.
http://www.youtube.com/watch?v=u
38LjCOvDZU&feature=related