Which statements about cell division are CORRECT?

1. Which statements about cell division are CORRECT? • statements 1 and 3 • statements 1 and 4 • statements 2 and 3 • statements 2 and 4

2. Today we will learn: • Who is the father of Genetics? • What is heredity? • What are traits? • Phenotypes vs Genotypes • Homozygous vs heterozygous

3. Mendel’s Laws of ___Genetics Why we look the way we look... http://learn.genetics.utah.edu/content/begin/traits/

4. What is heredity? • The passing on of characteristics (traits) from parents to offspring • _Genetics__ is the study of heredity

5. GregorMendel • Austrian monk • Considered the “father of genetics” • The first person to succeed in predicting how traits would be transferred from one generation to another • using the garden pea plant

6. Mendel used peas... • They reproduce sexually • They have two distinct, male and female, sex cells called _gametes_. • Their traits are easy to isolate

7. Mendel crossed them • _fertilization_ - the uniting of male and female gametes • Cross - combining gametes from parents with different traits

8. Types of pollination/fertilization Cross-pollination self-pollination

9. Questions • What did Mendel cross? • What are traits? • What are gametes? • What is fertilization? • What is heredity? • What is genetics?

10. What Did Mendel Find? • He discovered different laws and _rules_ that explain factors affecting heredity.

11. Rule of Unit Factors • Each organism has two _genes_ for each trait • Alleles - different forms of the same gene • Genes - located on chromosomes, they control how an organism develops

12. Rule of Dominance • The trait that is observed in the offspring is the dominant trait (uppercase) • The trait that disappears in the offspring is the recessive trait (lowercase)

13. Law of Segregation • The two alleles for a trait must separate when gametes are formed. • A parent randomly passesonly oneallele for each trait to each offspring.

14. Law of Independent Assortment • The genes for different traits are inherited independently of each other.

15. Genes and Dominance • Mendel came to two conclusions: • Factors that are passed/inherited from one generation to the next determine inheritance. • The Principle of Dominance - states that some alleles are dominant and some are recessive.

16. Questions... • How many alleles are there for each trait? • What is an allele? • How many alleles does a parent pass on to each offspring for each trait

17. Questions... • What do we call the trait that is observed? • What case(upper or lower) is it written in? • What about the one that disappears? • What case is it written in?

18. Phenotype & Genotype • phenotype - the way an organism looks • red hair or brown hair • genotype - the gene combination of an organism • AA or Aaoraa

19. Heterozygous & Homozygous • Heterozygous - if the two alleles for a trait are different (Aa) • _Homozygous - if the two alleles for a trait are the same (AA or aa)

20. Dihybrid vs Monohybrid • Dihybrid Cross - crossing parents who differ in two traits (AAEE with aaee) • Monohybrid Cross - crossing parents who differ in only one trait (AA with aa)

21. Questions... • What is the phenotype? • What is the genotype? • What is homozygous? • What is heterozygous? • What is monohybrid crossing?

22. Which genotype is heterozygous for two traits? • ggTt • GgTt • GgTT • GGTT

23. Punnett Square • Developed by Reginald _Punnett_. • A diagram used to show the probability or chances of a certain trait being passed from one generation to another.

24. Probability • The likelihood of a particular event occurring. Probability • Can be expressed as a fraction or a percent. • Example: coin flip.

25. 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

26. 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:

27. Using a PUNNETT SQUARE • Letters stand for dominant and recessive alleles • An uppercase letter stands for a dominant allele • Lowercase letters stand for recessive alleles

28. 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:

29. Using a PUNNETT SQUARE • The two-letter combinations are the possible genotypes of offspring. • They are: Rr, Rr, rr, and rr genotypes • From this it is possible to determine the probability (chance) that a flower will have a red phenotype (2/4 or 50%) or a white phenotype (2/4 or 50%)

30. Reading Punnett squares • Allele letters are placed above and to the left of the square • Offspring are placed in the square. • Capital letters (Y) represent dominant alleles. • Lower case letters (y) represent recessive alleles.

31. What can you tell me from this punnet square?

32. Punnett square review:

34. What is independent assortment? • Chromosomes/genes separate independently • during the • formation of • gametes.

35. The dihybrid cross • Punnett square on board:

36. Putting it all together! T = Tall Plants Mom and Dad are both heterozygous t = short plant Male gametes T t T TT Tt Female Gametes t tT tt Genotypic ratio: Phenotypic ratio:

37. Let’s Practice! http://www.nature.ca/genome/04/041/0414_e.cfm http://glencoe.mcgraw-hill.com/sites/0078778066/student_view0/chapter5/math_practice.html http://www.zerobio.com/drag_gr11/mono.htm

38. How well did you do today? • Which parts of this Punnett square would contain the genotype that results in the expression of only the recessive phenotype? • parts 1 and 2 • parts 1 and 4 • parts 2 and 3 • parts 3 and 4