1. Chapter 6 Meiosis and Mendel

2. 2 major different groups of cells: Somatic CellsGerm Cells Body cells DNA from these cells not passed on Diploid cells Found in reproductive organs Develop into gametes DNA passed on to kids Haploid cells Gametes = sex cells  Egg & sperm

3. Diploid = 2 copies of a chromosome Haploid = 1 copy of a chromosome

4. They are homologous chromosomes  the same type of info from each parent Chromosomes come in pairs  1 from mom, 1 from dad

5. Your chromos can either be autosomes or sex chromos Autosome = any chromo that isn’t a sex chromo Sex chromo = X & Y

6. So how do we get gametes? Meiosis! Meiosis is a lot like mitosis, but there are 2 divisions so we can end up with ½ the chromos

7. Meiosis I  cell goes through PMAT Homologous chromos get separated New combos of chromos in haploid cells because arrangement is random

8. Crossing over during Meiosis I helps create genetic diversity

9. Meiosis II  PMAT again (but no interphase this time) Sister chromatids get separated End with 4 cells that are all different

10.  This has to do with 1. size of cell 2. division of resources Males end up with more sperm from the process than women do eggs

11. Comparing mitosis and meiosis MitosisMeiosis 2 identical cells Diploid cells Happens over lifetime Used for growth & repair 4 different cells Haploid cells Only at certain times in life Used for reproduction

13. More dead guys to add to our “Important People” chart PersonOriginTime Frame Importance Gregor Mendel AustrianMid 1800’s “Father of Genetics” –bred pea plants to observe inheritance Reginald Punnett BritishEarly 1900’s Developed the Punnett Square

14. Important words…. TermMeaning GeneticsStudy of biological inheritance TraitsCharacteristics that are inherited PurebredGenetically uniform (kids are the same as parents) HybridGenetically different CrossMating of 2 organisms

15. Mendel would cross purebred plants  if he saw change it came from his experiment Original plants were the P (parental) generation Offspring are called F 1 (first filial)

16. Mendel noticed some traits would disappear in F 1, but show up in F 2 The “hidden” trait usually showed up in a 3:1 ratio in F 2

17. 2. Organisms inherit 2 copies of each gene (1 from each parent) Mendel’s conclusions… so far 1. Traits are inherited as independent units Law of Segregation 3. Only 1 copy of each gene in gametes  they have to segregate

18. More important words…. TermMeaning GeneDNA w/instructions for protein AlleleDifferent forms for the same gene Homozygous2 of the same allele for a gene Heterozygous2 different alleles for a gene GenotypeGenetic makeup PhenotypePhysical traits Heterozygous Homozygous

19. The principle of dominance = some alleles are dominant, others are recessive Dominant will always appear, even with 1 copy Recessive will only show if NO dominant trait

20. Dominant allele = capital letter Ex. tall = T Recessive allele = lower case letter Ex. short = t

22. Punnett Square = a grid to predict genotypes from a cross Parent 1’s alleles Parent 2’s alleles Phenotypic Ratio = 3 brown: 1 blue Genotypic Ratio = 1 BB: 2 Bb: 1 bb Hetero vs. Hetero Monohybrid cross : one trait cross

23. Hetero vs. Homo

24. Homo vs. Homo

25. Testcross = cross between an unknown and a recessive phenotype

26. Dihybrid cross: two trait cross Mendel found traits didn’t affect each other Law of independent assortment: allele pairs separate independently during gamete formation

27. Probability = the likelihood that a particular event will occur Punnett squares/inheritance are related to probability

28. Heads = 1 Ex. Coin Flip Total options = 2 = ½ or 50% Past outcomes DO NOT affect future ones