2. Ch.8 continued Sexual reproduction

3. What does the term homologous mean? What does the term homologous mean? Same or same function Same or same function How many chromosomes are there in this picture? How many chromosomes are there in this picture? 2, 4 chromatids 2, 4 chromatids

4. Are the versions (alleles) of the genes identical on homologous chromosomes? Are the versions (alleles) of the genes identical on homologous chromosomes? Not necessarily, notice in the picture the darker and lighter version of the genes. Not necessarily, notice in the picture the darker and lighter version of the genes. Are genes always at the same location (locus) on the homologues? Are genes always at the same location (locus) on the homologues? Yes, Blue,green and purple are always in the same location Yes, Blue,green and purple are always in the same location What do we call the chromosomes that are the same for both females and males (1-22)? What do we call the chromosomes that are the same for both females and males (1-22)? Autosomes Autosomes The X and Y are called the _____ chromosomes The X and Y are called the _____ chromosomes Sex chromosomes Sex chromosomes

5. What does diploid mean? What does diploid mean? The cell has two sets of homolgous chromosomes, one set from mom and one from dad. The cell has two sets of homolgous chromosomes, one set from mom and one from dad. What does haploid mean? What does haploid mean? One set of chromosomes. One set of chromosomes. What are the two types of gametes produced during meiosis (sexual cell division) and are they haploid or diploid? What are the two types of gametes produced during meiosis (sexual cell division) and are they haploid or diploid? Sperm and egg are haploid Sperm and egg are haploid When do human cells become diploid? When do human cells become diploid? After fertilization - sperm (23) meets egg(23) = zygote (46) After fertilization - sperm (23) meets egg(23) = zygote (46)

6. The stages of meiosis are different from mitosis When are the chromosomes duplicated? When are the chromosomes duplicated? S phase of interphase S phase of interphase What do you notice happening during prophase? What do you notice happening during prophase? Crossing over Crossing over What do you think is happening during crossing over? What do you think is happening during crossing over? Pieces of homologous chromosomes are breaking off and exchanging Pieces of homologous chromosomes are breaking off and exchanging How do the chromosomes line up at the equator? How do the chromosomes line up at the equator? They line up as homologous pairs They line up as homologous pairs

7. The stages of meiosis The stages of meiosis Unlike mitosis which had 1 division, how many divisions in meiosis? Unlike mitosis which had 1 division, how many divisions in meiosis? 2 How do the chromosomes line up this time, in division 2? How do the chromosomes line up this time, in division 2? In a single file since the homologous chromosomes were already separated. In a single file since the homologous chromosomes were already separated.

8. What are some of the differences between mitosis and meiosis? What are some of the differences between mitosis and meiosis? MitosisMeiosis 1 division2 divisions Chromosomes line up at single file Chromosomes line up as homologous pairs Produces 2 identical diploid cells Produces 4 different haploid cells

9. What is the difference between these two pictures? What is the difference between these two pictures? Left both blues are on the left, right blue and red are on opposite sides Left both blues are on the left, right blue and red are on opposite sides How many different possibilites for human combinations? How many different possibilites for human combinations? 2 23 = 8 million combinations with our 23 homologous chromosomes 2 23 = 8 million combinations with our 23 homologous chromosomes How does this show independent assortment? How does this show independent assortment? Where the one set of chromosomes (large set) goes has nothing to do with where the other set(Small set) goes. Where the one set of chromosomes (large set) goes has nothing to do with where the other set(Small set) goes.

10. Independent assortment Independent assortment More independent assortment More independent assortment

11. What type of chromosomes are these? What type of chromosomes are these? Homologous Homologous How do we know they are homologous? How do we know they are homologous? They have the same genes, only the versions are different. They have the same genes, only the versions are different.

12. What versions of the genes did the mouse on the right inherit? What versions of the genes did the mouse on the right inherit? The recessive white coat and red eyes. The recessive white coat and red eyes. What about the mice on the left? What about the mice on the left? We don’t know because they have the dominant traits theymay have the recessive homologuos chromosome as well. We don’t know because they have the dominant traits theymay have the recessive homologuos chromosome as well.

13. What is happening in this picture? What is happening in this picture? Crossing over Crossing over What is the chiasma? What is the chiasma? The location where crossing over happens. The location where crossing over happens.

14. How many different combinations from crossing over? How many different combinations from crossing over? 4, 2 the same as original, 2 recombinants 4, 2 the same as original, 2 recombinants

15. What process is being illustrated? What process is being illustrated? Karyotyping Karyotyping

16. What is the sex of this person? What is the sex of this person? Female Female Do they have the normal number of chromosomes? Do they have the normal number of chromosomes? Yes Yes Are there any genetics problems? Are there any genetics problems? You can’t tell from this karyotype You can’t tell from this karyotype

17. Is this a normal Karyotype? Is this a normal Karyotype? No, one too many chromosome 21s - Down’s Syndrome No, one too many chromosome 21s - Down’s Syndrome

18. What does this graph show? What does this graph show? As age of mother increases the number of Down’s syndrome births increases As age of mother increases the number of Down’s syndrome births increases

19. When meiosis goes wrong, what is it called? When meiosis goes wrong, what is it called? Nondisjunction Nondisjunction What happened to the number of chromosomes in each gamete? What happened to the number of chromosomes in each gamete? Two have one too many, two have one too few. Two have one too many, two have one too few.

20. How many gametes are affected by nondisjunction in meiosis II? How many gametes are affected by nondisjunction in meiosis II? Two, one has n+1 and one has n-1 Two, one has n+1 and one has n-1 When the egg with too many is fertilized by a normal sperm the zygote will have ___ extra chromosome(s) When the egg with too many is fertilized by a normal sperm the zygote will have ___ extra chromosome(s) 1

21. What causes Klinefelter’s syndrome? What causes Klinefelter’s syndrome? One or more extra X chromosomes One or more extra X chromosomes Why might that cause infertility? Why might that cause infertility? Mismatched chromosomes cannot line up correctly at metaphase Mismatched chromosomes cannot line up correctly at metaphase

22. What is the sex of this person? What is the sex of this person? Male with Klinefelter’s syndrome Male with Klinefelter’s syndrome

23. Which of the sex syndromes is most likely to happen? Which of the sex syndromes is most likely to happen? Metafemale Metafemale

24. X0 - Turner’s syndrome The fact that women with Turner’s syndrome have heart problems tells you what about the X chromosome? The fact that women with Turner’s syndrome have heart problems tells you what about the X chromosome? There must be gene on the X for heart formation There must be gene on the X for heart formation

25. Which chromosomal defect is the worst? Which chromosomal defect is the worst? A deletion A deletion Which defect is probably the least problematic? Which defect is probably the least problematic? Inversion Inversion

26. What is the Philadelphia Chromosome? What is the Philadelphia Chromosome? When chromosome 22 has a piece of 9 - leading to a type of leukemia When chromosome 22 has a piece of 9 - leading to a type of leukemia What causes Cri du Chat? What causes Cri du Chat? A deletion on chromosome 5 A deletion on chromosome 5

27. Gender testing Gender testing