1. Gene Regulation

2. Regulatory genes Promoter: where RNA polymerase attaches. TATA box: a segment on eukaryotic genes that positions RNA polymerase in the right place. Regulatory Sites: located before the promoter site where proteins can bind to regulate the rate of transcription of a gene. Activators bind to increase the rate of transcription Repressors bind to decrease the rate of transcription

3. Gene Regulation Activators Open up packaged DNA Attract and place RNA polymerase Repressors Block access of RNA polymerase

4. Regulatory sites Promoter (RNA polymerase binding site) Start transcription DNA strand Stop transcription Typical Gene Structure

5. Developmental Genes HOX genes: control when genes are turned on and off to help cells differentiate into different types of cells.

6. Gene Mutations

7. A permanent change in an organisms DNA. Mutations can be a result of mistakes during replication or a mutagen (an agent in the environment that can change DNA)

8. Mutations Point mutation – one nucleotide is changed very often fixed during DNA Replication Three types Substitutions Insersions Deletions

9. Substitutions Substitutions – One nucleotide is substituted for another. Nonsense – if it is not caught, this can make an early stop codon, causing the protein sequence to end prematurely. Missense – Only 1 amino acid changes and the rest remain the same. Silent- The changed nucleotide codes for the same amino acid

11. Frameshift Frameshift mutations shift the sequence over and can disrupt all amino acids after the mutation and therefore large amounts of the protein. Types of Frameshift mutations Insertion: a DNA nucleotide is inserted into a sequence Deletion: a DNA nucleotide is taken out of a sequence.

14. CHECK FOR UNDERSTANDING Turn to a partner and describe a non-sense mutation. The next person describes a frameshift. Of all the types, which do you think causes the most problems?

15. Chromosomal Mutations

16. Instead of affecting only one nucleotide like point mutations, Chromosomal mutations affect whole genes. Often caused either during crossing over (prophase I), metaphase I, or metaphase II of meiosis.

17. Crossing over Crossing over is when genetic information is swapped between chromosomes. This is a good thing because it leads to more genetic diversity and the possibility of new traits. Sometimes, however, mistakes in crossing over occur that cause mutations.

18. Gene Deletion and Duplication If the chromosomes do not line up properly in prophase I of meiosis. When crossing over occurs, one of the chromosomes has a duplicate of some genes, and the other chromosome is lacking that gene.

19. Gene Inversion Sometimes, chromosomes get twisted up and end up forming new bonds within the same chromosome. This causes a section of the DNA to be inverted.

20. Gene Translocation Exchange of DNA on non-homologous chromosomes. Many cancers are caused by this mutation.

21. Chromosomal Mutations Deletion: AC-DEF Duplication: ABBC-DEF Inversion: AED-CBF Translocation: GH-IDEF A part of a nonhomologous chromosome attaches.

22. Deletion Duplication Inversion Translocation Chromosomal Mutations

23. Non-disjunction Sometimes, genes do not separate properly during meiosis. EX: Down’s Syndrome

24. Results of Non-disjunction Monosomy: Only 1 of a set of chromosomes. Trisomy: Three sets of a chromosome. Polyploidy: more than 3 sets of a chromosome. Found in some plants

25. CHECK FOR UNDERSTANDING What is the difference between a chromosomal mutation and a point mutation? What would you consider the following change: ABC. DEFG  ABC. FEDG ? What would you consider the following change: ABC. DEFG  ABBC. DEFG ? What is the cause of monosomy, trisomy, and polyploidy mutations?