1. Protein Synthesis

2. What? Where? When? DNA  RNA  Protein
WHAT: Protein synthesis is the process of making proteins from the DNA code. There are two steps: Transcription & Translation.
DNA  RNA  Protein
WHERE:
Transcription: Nucleus
Translation: Cytoplasm
WHEN: Whenever a protein is needed somewhere in the body.
Ex: Enzymes, Hormones, Pigments

3. Gene Expression Expressed = turned into a protein.
The phenotype is determined by the genes expressed.

4. 2 Steps to Protein Synthesis:
1. Transcription 2. Translation

5. Transcription DNA  RNA
RNA Polymerase (enzyme) adds RNA nucleotides to create messenger RNA (mRNA).
mRNA carries the copied DNA code from nucleus to cytoplasm.
Occurs in the nucleus.

6. Messenger RNA

8. REMINDER: RNA nitrogenous bases: A, U, G, C A bonds with U
G bonds with C
Ribose Sugar

10. DNA vs. RNA DNA RNA Sugar = deoxyribose Sugar = ribose
Double-stranded molecule
Single-stranded molecule
Thymine bonds with adenine
Uracil instead of thymine

12. Translation mRNA  protein
The ribosome reads the copied mRNA code and attaches amino acids together to make a protein.
Amino acids are connected together by peptide bonds.
Occurs in the cytoplasm.

13. How does the ribosome read mRNA?
The ribosome reads the mRNA code in codons.
Codon: 3 nitrogenous RNA bases in a row. Each codon codes for 1 amino acid.
Ex: AUG = Methionine

16. Where are the amino acids?
Transfer RNA (tRNA) molecules carry the amino acid to the ribosome.
Each tRNA has an anticodon that complements the mRNA codon.
Ex: mRNA codon: AUG
tRNA anticodon: UAC
-AUG codes for Methionine
-The tRNA with antiocodon UAC carries amino acid Methionine

19. Summary:

20. What is the difference between DNA Replication & Protein Synthesis?
DNA Replication: DNA  DNA
***********************************
Transcription: DNA  mRNA
Translation: mRNA  Protein

21. How can we avoid mutations (errors)?
Code has duplicates
Sometimes a small error does not ruin the protein being made.
Start Codon:
AUG
Methionine
Stop Codons:
UAA, UGA, UAG

22. KEY FACTS TO REMEMBER:
DNA is the genetic material.
DNA codes for protein (but it cannot leave the nucleus, so it creates a “messenger” (mRNA) to bring the code to the ribosome in the cytoplasm.
The amino acid chart is based off of the mRNA codons (not tRNA anticodons).