Aim:

1. Do Now Aim: Describe how your body uses DNA? What is DNA used to code for? Homework: Castle Learning Assignment #7, Test Friday, Quarterly Thursday of next week

2. Review • Describe transcription and where it occurs within the cell? • What is the difference between mRNA and tRNA? • How do ribosomes play a role in protein synthesis? • What happens if RNA polymerase makes a mistake transcribing the gene?

3. Genetic Mutations

4. Mutations • Gene mutations occur in DNA. • These mutations may be inherited or may occur over time. • Not all mutations are harmful. • A mutation in DNA is a change in a base pairing that may result in an altered protein.

5. Mutations • Base pairs change • May or may not alter amino acid sequence • Met-Ala-Trp-Arg-Ser-Asp-Gly-Lys-Stop A change in amino acid sequence will change the protein structure.

6. Types of Mutations • Point Mutations: Base pair error • Substitution: when a single base pair is substituted for another • Deletion: when a base pair is removed • Insertion: when a base pair is added • Deletion and insertion can cause a frame shift. • Triple repeat mutation causes a repeat of 3 amino acids. Such disorders are fragile x, huntingtons, myotonic dystrophy.

7. Point Mutations – a change in DNA involving a single base pair May change amino acid or may not.

8. Point mutations - substitution • A substitution of an A for a T in the 6th codon cause diseases such as sickle cell

9. Insertion/Deletion Mutations

10. Trinucleotide Repeat Disorders • This causes diseases such as Huntingtons disease. • Caused by an excessive amount of CAG repeats • Normal level 6-35 repeats • Disease level 38-180

11. Causes of Mutations • Can be passed down from parents. • Chemicals mutagens can cause mutations • Radiation • Sunlight / UV light • Replication or transcription errors

12. Aim: What is the difference between a chromosomal mutation and a gene mutation? Do Now State three causes of mutations. Homework: Text Book Pg 353 questions 1-11, test Friday

13. Mutations Alter Proteins • Proteins form improperly • May be shorter or longer then normal • Go to areas where they are not needed Normal Hemoglobin Mutated Hemoglobin

14. What do we know about Mutations?

15. Questions: • State why deletion or insertion mutations could be mush worse than a point mutation? • When there is a mutation what is going to be affected? • How could a mutation through off homeostasis?

16. Chromosomal Mutations

17. Sources of mutations • Nondisjunction • during meiosis a cell ends up with only one member of a homologous chromosome. An unequal separation. This can lead to disease such as down syndrome. • http://www.zerobio.com/independent_assortment.htm

19. Sources of mutations • Polyploidy • when one or both of the parents gives a full diploid set of chromosomes leaving the offspring with a 3n or 4n number. • This condition occurs in plants for the most part. The plants that this occurs in with are sterile and also larger.

20. Sources of mutations • Chromosome structure alterations • Translocation • when a segment of one chromosome breaks off and binds to a non homologous chromosome.

21. Sources of mutations • Addition • occurs when a segment breaks off one chromosome and reattaches to another

22. Sources of mutations • Inversion • occurs when a segment breaks off and reattaches in reverse on the same chromosome.

23. Sources of mutations • Deletion • occurs when a segment breaks off and does not reattach to any other chromosome.