Central Dogma of Molecular Biology

1. Central Dogma of Molecular Biology • Genetic information flows in one direction – • from DNA to RNA to proteins.

2. Bellringer What do these words mean to you?Write a short 2 word definition for each • 1. Mutation • 2. Duplication • 3. Deletion • 4. Insertion • 5. Translocation • 6. Inversion • 7. Substitution

3. KEY CONCEPT Mutations are changes in DNA that can affect phenotype

4. What are Mutations? (video link)

5. Mutations are changes to DNA that may be • Harmful • Helpful • Have no effect.

6. When Mutations Occur • Errors can occur during: DNA Replication Protein Synthesis Meiosis .

7. Causes of Mutations 2. Mutagens – Environmental factors that cause changes in DNA Examples: - Radiation - Chemicals in environment .

8. The effect mutations have on an organism’s physical characteristics depends on: • The number and type of genes involved • Type of cell the mutation occurs in – somatic or sex

9. Mutations in Somatic Cells: • Affect only the organism they occur in. • Cannot be passed to offspring.

10. Mutations in Sex (Germ) cells: • May be passed to offspring

11. Two Categories of Mutations: 1.Single Gene– affects one gene – usually caused by an error in DNA replication 2. Chromosomal – affects chromosomes – usually error in meiosis . Usually more harmful since many genes are affected.

12. Types of Chromosomal Mutations • Translocation • Duplication • Nondisjunction • Deletion • Inversion

13. TRANSLOCATION(“transfer location”) • Piece of one chromosome breaks off and moves to a nonhomologouschromosomes.

14. DUPLICATION. • Two or more copies of the same gene on a chromosome .

15. NONDISJUNCTION • Homologous chromosomes don’t separate in Anaphase I • Sister chromatids don’t separate in Anaphase II

17. Deletion • Section of chromosome containing one or more genes is removed

18. Inversion • Section of a chromosome flips its position

20. Single Gene Mutations • Usually occur in DNA replication • Affect one gene and the protein made from it

22. Frameshift Mutation • Caused by adding or removing 1-2 bases • Changes the reading frame • .

23. Type of Frameshift Mutation .Deletion - one or more bases are deleted; shifts the reading frame

24. Type of Frameshift Mutation Insertion - one or more bases are added; shifts the reading frame

25. mutated base Point Mutations • One nucleotide is replaced by another.

26. Types of Point MutationsDetermined by their outcomes

27. Nonsense point mutation • Change codes for a STOP codon • Full protein not made • “NO” STOP

28. Missense Point Mutation * Codes for wrong amino acid* May be harmful or beneficial – depends…

29. Silent point mutationDoes not result in a different amino acid or protein made.DNA changes but its expression (phenotype) does not.

30. Results of mutations may be: • Harmful – needed protein isn’t made • Have NO EFFECT – are not harmful or helpful • Beneficial are favored by natural selection – rarely occurs

31. Mutations increase genetic variety Natural selection favors mutations that provide survival advantage.

32. Laron Syndromemutation that causes dwarfism also protects against cancer and diabetes. • ABC Evening News - Laron Syndrome

33. Mutations in body cells do not affect offspring. • Only Mutations in sex cells affect offspring. • Natural selection favors mutations that provide an adaptation that has survival advantage