1. Translation & Mutations

2. IV.How to Make Proteins: *DNA goes through Transcription to make mRNA. The mRNA works with tRNA and rRNA to make proteins in Translation

3. A.Protein Structure 1.Proteins are made of amino acids, linked together in chains. There are 20 amino acids. 2.The sequence of amino acids determines how the protein will twist and fold into a 3D shape. 3.A chain of amino acids is a polypeptide.

4. B.Genetic Code – a sequence of mRNA nucleotides (bases) can be translated into a sequence of amino acids 1.3 mRNA nucleotides is called a codon. 2.Each codon codes for 1 specific amino acid.

5. 3.There are two special codons: a)Start Codon – 3 mRNA nucleotides with the bases AUG. This codon triggers a ribosome to begin translation. AUG codes for the amino acid methionine, so this is the first amino acid of every protein. b)Stop Codon – 3 mRNA nucleotides with bases UAA, UAG, or UGA. This codon tells a ribosome to stop translating mRNA.

6. 4.tRNA: one end holds an amino acid & the other end is an anticodon. The anticodon is three bases complementary to the bases on the mRNA. Ex: mRNA: CAU GGA tRNA anticodon: GUA CCU

7. V.Translation – taking mRNA, “reading” it to bring the correct amino acids and connect them to make a protein. 1.mRNA is made from a single strand of DNA in the nucleus (transcription). 2.mRNA is carried from the nucleus to the cytoplasm. 3.mRNA goes to a ribosome (rRNA). The ribosome attaches to the start codon.

8. 4.A tRNA attaches to an amino acid in the cytoplasm and carries it to the mRNA and ribosome. 5.Each tRNA lines up its anticodon with the codon on the mRNA (base-pairing rules). *For example, if the mRNA codon is CCU, the anticodon on the tRNA will be GGA. Now the amino acid at the other end of the tRNA is in the right position to form an amino acid chain.

10. 6.Amino acids are connected to make a protein. 7.When a stop codon is reached, no amino acid is added. The mRNA, ribosome, tRNA’s, and protein are released into cytoplasm.

11. Mutations - changes in DNA sequence I.Gene Mutations: result from changes in a single gene A.Point Mutations: affect 1 DNA nucleotide 1.Also called substitutions, as 1 DNA nucleotide is substituted for another

12. B.Frameshift Mutations: shift the “reading frame” of the genetic message Insertion Deletion

13. II.Chromosomal Mutations: changes in the # or structure of chromosomes A.Deletion: loss of all or part of a chromosome B.Duplication: segment of a chromosome is repeated C.Inversion: part of a chromosome becomes oriented in reverse directions D.Translocation: part of 1 chromosome breaks off and attaches to another chromosome

14. Chromosomal Mutations