1. Chromosomes

2. Human Chromosome Autosomes – (#1-22) 44 chromosomes that everyone has no matter what sex they are Autosomes – (#1-22) 44 chromosomes that everyone has no matter what sex they are Sex chromosomes – (#23) 2 chromosomes that determine sex, Sex chromosomes – (#23) 2 chromosomes that determine sex, 46 total chromosomes, 23 pairs 46 total chromosomes, 23 pairs Females = XX Females = XX Males = XY Males = XY X chromosomes has 1200 + genes found on it; the Y chromosome has only 140 genes found on it X chromosomes has 1200 + genes found on it; the Y chromosome has only 140 genes found on it

3. Human Chromosome Karyotype Karyotype Picture of chromosomes arranged in pairs of decreasing size Picture of chromosomes arranged in pairs of decreasing size They show us They show us Homologous Chromosomes: Homologous Chromosomes: A pair of matching chromosomes in an organism, with one being inherited from each parent. Sex Chromosomes Sex Chromosomes Autosome Autosome

4. How is sex Determined By the male sperm By the male sperm Male sperm carry either an X or a Y chromosome Male sperm carry either an X or a Y chromosome Female eggs only carry an X chromosome Female eggs only carry an X chromosome

5. Genetic Variation

6. Sources of Variation http://learn.genetics.utah.edu/content/variati on/sources/ http://learn.genetics.utah.edu/content/variati on/sources/ Three Main Sources: – Crossing over during Meiosis – Mutations during replication – Environmental factors

7. Crossing Over: New Genetic Combinations during Meiosis https://highered.mheducation.com/sites/983 4092339/student_view0/chapter11/meiosis_ with_crossing_over.html https://highered.mheducation.com/sites/983 4092339/student_view0/chapter11/meiosis_ with_crossing_over.html

8. What is a Mutation? Mutation is a natural process that changes a DNA sequence. The whole human family is one species with the same genes. Mutation creates slightly different versions of the same genes, called alleles. These small differences in DNA sequence make every individual unique. Genetic variation is useful because it helps populations change over time. – Variations that help an organism survive and reproduce are passed on to the next generation. – Variations that hinder survival and reproduction are eliminated from the population.

9. Review: Gene Mutations “Base mutations” Small changes to DNA – Happens during DNA replication – One or several bases – Change can be positive, negative, or neutral – Could effect protein synthesis Can be passed to offspring if in gametes

10. Chromosomal Mutations Large changes to DNA – Can be structural – Can be a change in chromosome number – Usually a meiosis error, so not always a mutation passed from parents to offspring Usually lethal, if fetus survives tends to cause widespread abnormalities Diagnosable through karyotyping or gene testing