1. Genetics & Heredity

2. Who was Gregor Mendel?

3.  Austrian monk who studied mathematics and science  As a boy he could predict the possible types of flowers and fruits that would result from crossbreeding two plants in his father’s garden

4. Who was Gregor Mendel?  Curiosity about the connection between the color of a pea flower and the type of seed that same plant produced inspired him to begin experimenting with garden peas in from one generation to the next.

5. What is GENETICS?

6. The study of how traits are inherited through the interactions of genes.

7. What is a GENE?

8.  The material that controls which traits are expressed in an organism  Genes come in pairs and offspring inherit one copy of each gene from each parent

9. HEREDITY The passing of traits from parent to offspring

10. ALLELE ALLELE  The different forms of a trait that a gene may have  One form of a gene

11. TRAIT  Ways of looking, thinking, or being  Traits that are genetic are passed down through the genes from parents to offspring

12. Describe DOMINANT  A trait that covers over, or dominates, another form of that trait  Trait that always shows up, even when only one of the two alleles is in the dominant form  Shown by a capital letter

13. Describe RECESSIVE  A trait that is covered over, or dominated, by another form of that trait and seems to disappear  Hidden when the other copy of the gene contains the dominant allele.  A recessive allele shows up only when there is no dominant allele present  Shown with a lower-case letter

14. What is HOMOZYGOUS?

15.  Both alleles [forms of the gene] are the same (TT)  When offspring inherit two dominant genes, (one dominant gene from each parent) they are said to be homozygous dominant  When offspring inherit two recessive genes, (one recessive gene from each parent) they are said to be homozygous recessive

16. What is HETEROZYGOUS?

17.  When alleles occur in different forms (Tt)  When offspring inherit one dominant gene and one recessive gene, they are said to be heterozygous  Since the dominant gene will be expressed, they are said to be heterozygous dominant

18. GENOTYPE An organism's genetic makeup Tt TT tt

19. PHENOTYPE Outward physical appearance and behavior of an organism

20. What is a PUNNETT SQUARE?

21.  A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine  A way to show phenotype & genotype  A chart that shows all the possible combinations of alleles that can result when genes are crossed

22. What is a PUNNETT SQUARE?  Letters stand for dominant and recessive alleles  An uppercase letter stands for a dominant allele  Lowercase letters stand for recessive alleles

23. Describe CO-DOMINANCE

24.  When an organism has two different alleles for a gene that does not follow the dominant/recessive pattern  The organism shows a trait that is a blend of the traits represented by the two alleles  Also called INCOMPLETE DOMINANCE

25. Describe CO-DOMINANCE For example: The gene for the color of some flowers has one allele for red and one for white. When both alleles are present, neither is dominant, and the flower color is pink

26. Using a Punnett Square

27. What is a PUNNETT SQUARE?  A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine  A way to show phenotype & genotype  A chart that shows all the possible combinations of alleles that can result when genes are crossed

28. What is a PUNNETT SQUARE?  Letters stand for dominant and recessive alleles  An uppercase letter stands for a dominant allele  Lowercase letters stand for recessive alleles

29. Example: Tall is the dominant trait in pea plants Therefore T = tall and t = short

30. We also know that an organism gets 1/2 its genes from its mother and 1/2 from its father. So, lets look at some possibilities: Remember: T = tall t = short

31. What if Mom gives up a tall gene and Dad gives up a short gene? What letter represents the tall gene? What letter represents the short gene? So the offspring?

32. What if Mom gives up a tall gene and Dad gives up a tall gene? What letter represents the tall gene? So the offspring?

33. What if Mom gives up a short gene and Dad gives up a short gene? What letter represents the short gene? So the offspring?

34. Now for the possibilities Tt is called hybrid or heterozygous. In a hybrid the dominant trait always shows. The offspring would be tall (phenotype). Phenotype = physical makeup - what it looks like TT is called pure or homozygous. The offspring would also be tall. tt is called pure or homozygous The offspring would be short. This is the ONLY way a recessive trait shows.

35. Using a PUNNETT SQUARE To set up a Punnett square, draw a large square, and then divide it into 4 equal sections (also squares). It should look something like this:

36. Using a PUNNETT SQUARE

37. Rr pure or hybrid? homozygous or heterozygous rrpure or hybrid homozygous or heterozygous

38. Using a PUNNETT SQUARE Place one of the parents on top, and one on the left. You should get a something similar to this:

39. Using a PUNNETT SQUARE Finally, take each letter in each column and combine it with each letter from each row in the corresponding square. You should now have a picture close to this:

40. Using a PUNNETT SQUARE  The two-letter combinations are the genotypes of offspring