1. AP Bio: Thursday 3/15/12 Sexual Reproduction & Meiosis
Homework due tomorrow:
Lab 3B (Meiosis) Analysis Questions
Do Now:
On the handout…
Today’s Goals:
Explain the key steps of sexual reproduction
Review key vocabulary terms
Explain and model the steps and purpose of meiosis
Agenda:
Lecture/Discussion
Lab 3B: Modeling Meiosis w/ Pipecleaners

2. Asexual vs. Sexual Reproduction
Asexual Reproduction
One parent
Parent and offspring are genetically identical (clones)
Reproduce using MITOSIS (euks) or BINARY FISSION (proks) or by BUDDING or FRAGMENTATION
Sexual Reproduction
Two parents
Offspring are genetically different from parents
Reproduce using MEIOSIS (makes eggs and sperm) and FERTILIZATION (egg and sperm join)

3. Sexual Reproduction Life Cycle

4. Major Genetics Terms Gene: Alleles: Chromosome:
A section of DNA that holds instructions for making one protein
Ex: gene for hemoglobin protein
Alleles:
Different versions of a gene
Ex: normal hemoglobin allele vs. mutated hemoglobin allele
Chromosome:
A long strand of DNA, coiled and wrapped up, that contains many genes
Homologous Chromosomes:
 A pair of chromosomes that contain the same genes but not necessarily the same alleles

5. Major Genetics Terms (continued)
Diploid:
A cell that contains TWO COPIES of every chromosome (in homologous pairs)
All human body cells except gametes are diploid.
Haploid:
A cell that contains ONE COPY of every chromosome
Gametes are haploid. 
Gametes:
Egg or sperm cells, used in sexual reproduction.
Contain HALF the number of chromosomes as all other body cells (they are haploid)
Meiosis: The process of making gametes.
1 Diploid cell  4 Haploid cells
Separates homologous chromosomes into different cells
Unlike in mitotic cell division, the resulting daughter cells are NOT identical

7. Meiosis

8. Watch the video…

9. Lab 3B: Meiosis w/ Pipecleaners!

10. AP Bio: Friday 3/16/12 Details of Meiosis
Homework:
Take notes and be ready to present on your assigned problem set question
PS 15 due Wednesday 3/21/12
Do Now:
Get a copy of PS 15 and adjust the date (sorry!)
Read questions 3-7 and pick one or more that you’re interested in
Today’s Goals:
Explain how meiosis creates genetic diversity between gametes
Agenda:
Lecture/Discussion: Details of Meiosis

11. Start:
Start:
Meiosis I:
Mitosis:
Meiosis II:
End:
End:

12. Start: Diploid Cell Start: Diploid Cell End: 4 Haploid Cells
(46 Chromosomes
in Humans)
Start: Diploid Cell
(46 Chromosomes
in Humans)
Meiosis I: chromosomes line up with homologous pairs, which then separate (sister chromatids stay together)
Mitosis: chromosomes line up single file and sister chromatids split
Meiosis II:
sister chromatids split (like mitosis)
End: 4 Haploid Cells
(23 Chromosomes
in Humans)
Cells different from starting cell (half the # of chromosomes)
End: 2 Diploid Cells
(46 Chromosomes
in Humans)
Cells same as starting cell

13. Summary of Meiosis

14. Summary of Meiosis Final result:
DNA is replicated once
Chromosomes and cells are divided twice:
Meiosis I: Homologous chromosomes pair up and separate
Forms 2 haploid cells
Chromosomes still have sister chromatids
Meiosis II: Sister chromatids separate
Final result:
4 haploid gametes with HALF the number of chromosomes as the original cell
Gametes

15. Stages of Meiosis

17. Two Ways meiosis generates genetic diversity between gametes:

18. Two Ways meiosis generates genetic diversity between gametes:
1. Crossing over during Prophase I.
One sister chromatid trades a section of DNA with its homologous partner.
Creates new combinations of alleles on chromosomes.
Can happen at multiple places along the chromosome, allowing for a nearly infinite number of different gametes.

19. Two Ways meiosis generates genetic diversity between gametes:

20. Two Ways meiosis generates genetic diversity between gametes:
2. Independent alignment of homologous pairs during Metaphase I.
A cell with 2 homologous pairs yields 4 possible gametes.
How many are possible with 23 homologous pairs?

21. Sexual Reproduction Generates Genetic Diversity in 3 Ways:
Meiosis: Independent Alignment of Homol. Chromosomes in Metaphase I
Meiosis: Crossing Over
Fertilization: Random Selection of the Diverse Egg and Sperm Cells generated by Meiosis

22. Lab 3B Review…

23. AP Bio: Tuesday 3/20/12 Variations on Meiosis & Reproduction
Homework:
PS 15 due tomorrow. We WILL have class 7:20 sharp.
Do Now:
Hand in Transformation Lab Report and get back other labs
Group #3 – get ready to present
Everyone else – what do you think are some differences between making eggs and making sperm?
Today’s Goals:
Apply knowledge of meiosis to…
Various interesting and weird reproductive situations
Explain Mendel’s Laws of Inheritance
Agenda:
PS 15 Presentations
Chapter 14 – Reading & Worksheet