1. Unit 6 Notes: PROTEIN SYNTHESIS & MUTATIONS

2. (1) Protein Synthesis Basics
Overall Goal: Use DNA to put together the correct sequence of amino acids, building a specific protein molecule.
Steps:
1- DNA  RNA.
2- RNA  AMINO ACIDS (PROTEIN).
Keep In Mind: Your genetic code IS the unique order of nitrogenous bases!

3. (2) What is RNA? RNA = RiboNucleic Acid Structure: Types of RNA:
Nucleotide = Phosphate, Ribose Sugar, N.Base
Types of Nitrogenous Bases:
Uracil (U) pairs with Thymine (T)
Guanine (G) pairs with Cytosine ©
[U in RNA replaces A in DNA]
Types of RNA:
Messenger RNA (mRNA)
Ribosomal RNA (rRNA)
Transfer RNA (tRNA)

4. (3) Codons & Anticodons CODONS  ANTICODONS 
Codons are located on Messenger RNA (mRNA).
1 Codon = 3 Nitrogenous Bases
1 Codon = 1 Amino Acid
ANTICODONS 
Anticodons are located on Transfer RNA (tRNA).
1 Anticodon = 3 Nitrogenous Bases
1 Anticodon = 1 Amino Acid

6. (4) Transcription: DNA  RNA
Overall Goal: Take the code from DNA nitrogenous bases and copy it onto an RNA molecule.
Why??: DNA cannot leave the nucleus. DNA cannot be directly translated into protein.
Steps:
DNA strands unwound and separated by helicase.
The enzyme RNA Polymerase binds to DNA promoters.
RNA Polymerase matches up RNA bases with DNA bases.
END PRODUCT = 1 Strand of Messenger RNA (mRNA)
mRNA leaves the nucleus.
Keep In Mind: Only 1 strand of DNA needs to be transcribed since the bases are complimentary.

7. (5) Transcription Examples:
DNA Template: TAC—GCG—AAA—ACT
WHAT WOULD BE THE CORRESPONDING STRAND OF mRNA?

8. (6) Translation: RNA  Amino Acids
Overall Goal: Take the code from RNA molecule and translate it into an amino acid chain (protein).
Why??: DNA and RNA are only instructions. Proteins are the molecules that actually do things inside cells.
Steps:
mRNA moves through Ribosomal RNA (rRNA) 5’  3’.
Begin with the Start Codon, and End with the Stop Codon.
mRNA codons are matched up with tRNA anti-codons.
Every 3 bases (1 Codon), Transfer RNA (tRNA) brings 1 Amino Acid.
Amino Acids are bonded together atop tRNA molecules.
END PRODUCT = 1 Specific Polypeptide (Protein).
Keep In Mind: tRNA molecules are floating around waiting to match up their anticodons to mRNA codons during translation. They automatically have amino acids ready to go! 

10. (7) Translation Examples:
mRNA Strand: AUG—CGC—UUU—UGA
WHAT WOULD BE THE CORRESPONDING AMINO ACID SEQUENCE?

11. (8) What Are Mutations?
Mutations: Any change in the sequence of nitrogenous bases.
Types:
Missense vs. Nonsense
Point (Substitution, Deletion, Insertion)
Frameshift
Causes:
Cell errors
Chemical / UV exposure

13. (9) Types of Mutations Missense: Mutation changes type of amino acid.
Nonsense: Mutation prematurely stops translation.
Silent: Changes bases, but has no protein effect.
Point: Change 1 base along DNA sequence.
Substitution  Replace 1 base with a different one.
Insertion  Add 1 extra base into sequence.
Deletion  Remove 1 base from the sequence.
Frameshift: Any Insertion or Deletion mutations which shift the bases, changing the amino acid sequence.

16. DNA Template: TAC—GCG—AAA—ACT
(10) Mutation Examples:
DNA Template: TAC—GCG—AAA—ACT
Insertion:
Deletion:
Substitution:
Which of the above is/are Frameshift?
Which of the above is/are missense?
Which of the above is/are nonsense?