2. A C G C C T T G A T C T G T C G C A T T T A G C

4. Polypeptide: multiple dipeptides bonded together
Proteins: multiple polypeptides bonded together
smallest protein = 50 amino acids
Largest protein = amino acids
Each different sequence of amino acids codes for a different protein
Sections of folded chain will bond together to form cross-links
Different shapes can therefore code for different proteins

5. Proteins A-A-A-C-G-C-G-A…. Dipeptide Polypeptide (1 or more)
Amino acid + Amino acid + Amino acid…
Dipeptide
Polypeptide (1 or more)
Proteins

6. The DNA code:
The order of the nitrogenous bases in the DNA molecule is actually a “code” for the order of amino acids.
Each string of 3 nitrogenous bases codes for an amino acid.

7. If there are 4 nitrogenous bases (Adenine, Thymine, Cytosine, and Guanine) then there are 64 different 3 base sequences.
However, there are only 20 different amino acids in proteins. Therefore some amino acids have more than one code.
Today scientists know that genes are made of many nucleotides. The order of the bases codes for the amino acids that will be added to the polypeptide chain.

8. A-A-A-C-G-A-T-A-T-T-G-C-C-G-A A A U U U G C U A U C G G C U
Protein synthesis:
1) TRANSCRIPTION: takes place in the nucleus.
The nucleus will copy the DNA code for a polypeptide into a molecule of RNA.
The DNA strand separates for a short time to serve as a template (or pattern) for RNA.
Complimentary RNA nucleotides take their place on the DNA strand
(just like when DNA replicates, with one difference)
A-A-A-C-G-A-T-A-T-T-G-C-C-G-A A A U U U G C U A U C G G C U

9. When the RNA reaches a specific “STOP” code (a code of Nucleic acids e
When the RNA reaches a specific “STOP” code (a code of Nucleic acids e.g. UAC) it leaves the DNA strand.
The RNA strand is now a separate molecule that carries the complete code for one Polypeptide
The involved RNA in this step is known as messenger RNA or mRNA
Codon: group of 3 bases on RNA that codes for an amino acid

11. TRANSLATION: code amino acids
Once mRNA has copied the code, the next step is to actually create the polypeptides.
Transfer RNA tRNA
There are 20 different kinds of tRNA, one for each amino acid
The have a short tail on one end that can “pick up an amino acid”
Each tRNA can carry only one specific amino acid

12. tRNA At the base is an Anticodon. that complements the mRNA code
This is how the tRNA knows
where to put its amino acid.

14. Ribosomal RNA -- rRNA Formed in the nuclei of the cell.
A protein from the cytoplasm migrates in to the nucleus
rRNA joins with a protein to create a ribosome
rRNA + Protein = ribosome
The ribosome is where a polypeptide is assembled during protein synthesis

16. Nucleus
DNA strand
mRNA
tRNA
rRNA
Ribosome
tRNA
tRNA
rRNA
Protein
Amino Acid
Amino Acid
Amino Acid
Cytoplasm

17. Amino acids: the building blocks of proteins
simple atomic structure:
Central carbon atom bound to:
1 carboxyl group (COOH)
1 amino group (NH2)
1 hydrogen atom
1 side chain represented by “R” (meaning it is different in every amino acid)

19. Amino acids: the building blocks of proteins
The sequence of nitrogenous bases in DNA is the “code” that tells cells what amino acids to produce
There are 20 different amino acids that are commonly found in proteins
Every 3 nitrogenous bases code for an amino acid

20. Example: CAC is a nitrogenous base sequence that codes for the amino acid
histidine

21. Amino acids bond together by dehydration synthesis.
Peptide bond forms between the amino group of one molecule and the carboxyl group of another.
Resulting molecule is called a dipeptide