1. Chp: 12 Transcription & Translation

2. Genes and Proteins
Proteins function as Enzymes, build and repair cells, transport proteins
Genes code for proteins (genetic code)
Proteins are built from amino acids
Each nucleotide is composed of 3 nitrogen bases representing an amino acid called a codon

3. There are 64 different codons in the genetic code
Genetic code was figured out by studying E. coli.
Codons represent the same amino acids in all organisms.

4. Transcription
RNA differs from DNA in that it is only a single strand, contains a different sugar (ribose), and contains Uracil instead of Thymine
In RNA A binds with U

5. How to read the Amino Acid chart

7. Transcription
Enzymes make an RNA copy of a DNA strand. Results in the formation of a single stranded RNA molecule
Messenger RNA (mRNA)- the RNA copy that carries the information from DNA out into the cytoplasm of the cells
Carries info to the ribosomes so that proteins can be synthesized

8. Ribosomal RNA (rRNA)- portion of the DNA code for the RNA that makes up ribosomes
Helps to produce enzymes needed to bond amino acids together during protein synthesis

9. Steps in transcription
DNA helicases (enzymes) unzip DNA
Free RNA nucleotides pair with the complementary DNA by using RNA polymerases
When the base pairing is complete, mRNA breaks away from the DNA strand, leaves the nucleus, and enters the cytoplasm, then ribosome
If the DNA strand is AGC TAG CGA
the RNA strand would be UCG AUC GCU

12. Translation
The process of converting the information in a sequence of nitrogen bases in mRNA into a sequence of amino acids that make up a protein
Occurs on the ribosomes
Transfer RNA (tRNA)- brings amino acids to the ribosomes so they can be assembled into proteins
Each mRNA codon (3 letters) joins w/the anticodons of tRNA
End result of translation is the production of proteins

13. Steps in translation
The 1st codon of the mRNA strand attaches to the ribosome. The tRNA approaches the ribosome, the anticodon from tRNA binds w/the codon on mRNA.
The first codon of mRNA is AUG (start codon for protein synthesis), mRNA slides along the ribosome to the next codon
A new tRNA carrying an amino acid will pair w/the mRNA codon
When the 1st and 2nd amino acids are in place an enzyme will join them.

14. A chain of amino acids is formed until the ribosome reaches the stop codon on the mRNA (UAA)
The bond that holds the amino acids together is called a Peptide Bond.