1. Daily Agenda Daily Trivia Agenda Check Homework Notes on Genetic Crosses Groupwork on HW worksheets Homework

2. RR / BIO 137

3. What is genetics? Genetics is the study of HOW traits are passed from parents to offspring. –Offspring show some traits of each parent –These traits from parents are passed onto the offspring by sex cells

4. Body Cell vs. Sex Cell Body CellSex Cell make up most of the tissues and organs in body sperm or egg cell only Has 23 pairs of chromosomes (total=46 chromosomes) Has 23 chromosomes The chromosomes are paired up Only 1 of each chromosome

5. Chromosomes BODY CELL SEX CELL

6. Genes A gene is a small section of chromosome that determines a specific trait Genes are arranged on a chromosome Each chromosome carries specific genes gene Chromosome

7. Genes The genes on chromosomes in body cells are paired –2 genes represent a trait in each body cell Pair of chromosomes Gene 1Gene 2 Same Trait

8. Fertilization FERTILIZATION: we get genes from each of our parents The only way traits are passed onto offspring MOMDAD Offspring

9. Dominant Genes Genes that keep other genes from showing their traits EX: plant size “T” is for the tall gene for a tree Uppercase letters only

10. Recessive Genes The genes that do not show their traits when dominant genes are present Lowercase letters only EX: plant size “t” is the gene for a short tree

11. Dominant vs. Recessive Pure Dominant – an organism with 2 dominant genes for a trait Pure Recessive – an organism with 2 recessive genes for a trait Heterozygous – an organism with 1 dominant and 1 recessive gene for a trait –The dominant gene will overpower the recessive gene. –The dominant gene will be expressed

12. Example: Palm Tree Height DominantRecessive Gene is depicted with a capital letter Ex: T Gene is depicted by a lower case letter Ex: t TT = pure dominant tt = pure recessive Tt = heterozygous TT or Tt tt TALL SHORT

13. Punnett Square A way to show which genes can combine when and egg and sperm join Letters are used in place of genes Large letter = dominant gene (F) Small letter = recessive gene (f) Mother’s Genes Father’s Genes

14. Homework p. 11-12 211s

15. Daily Trivia Elephants can “hear” through their feet.

16. Agenda DT Agenda HW Check Finish Notes Punnett Squares Homework

17. Punnett Square Large letter goes first in heterozygous organisms (Ff) Let’s do a cross between a pure dominant male (sperm) for free earlobes (FF) and a female (egg) who is heterozygous for free earlobes (Ff) FFfFf FFfFf FFFF F f F is dominant over f

18. What are the expected results? F Free Earlobes Ff Free Earlobes Ff Free Earlobesf Attached Earlobes FfFf F f

19. Expected vs. Observed Results ExpectedObserved Can be calculatedActually seen PredictedNot Predicted Genotype: The combination of genes one has Phenotype: the physical trait that you can see What you expect to observe What you actually observed

20. Dominant/Recessive One allele is dominant over the other (capable of masking the recessive allele) PP = purple pp = white Pp = purple

21. Problem: Dominant/Recessive In pea plants, purple flowers (P) are dominant over white flowers (p) show the cross between two heterozygous plants. PpPp P p pp Pp PP - PP (1); Pp (2); pp (1) - ratio 1:2:1 - purple (3); white (1) - ratio 3:1 GENOTYPES: PHENOTYPES:

22. Punnett Square 5 Steps –Type of cross –Key –Cross –Square –Answer the question Practice Problems on the board Pages 13-16

23. Homework 2 Worksheets