1. Bell Work Hand in Diffusion Lab Write-Up stapled to the Lab Packet
Complete the questions on the Nucleus Bell Work

2. Ribosomes and The Golgi Apparatus

3. Overview: Ribosomes
Ribosomes read strands of mRNA and use those directions to make a protein
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

4. Overview Amino Acid 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.

5. 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

6. 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

7. 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

8. 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
Arginine
Tyr
A base
U base
G base
C base

9. 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.
Leucine
Tyr
Arg
A base
U base
G base
C base

10. Protein Synthesis: Translation
This process of adding amino acids to the chain continues until the ribosome encounters a stop codon.
Tyr
Arg
Leu
Val
Met
His
STOP!!!
A base
U base
G base
C base

11. 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.

12. 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

13. 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.

14. 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

15. 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).

16. 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.