1. Meiosis and Human Genetics

2. Outline of the day Turn in your lab reports at the front
More than 10 minutes late = bad
Any questions on last week’s lab?
Quiz
Introduction to the lab
Lab!
Check out
Get a stamp
Make sure I mark you down for attendance

3. Quiz
Ends 8 minutes after it’s started
Ends at: ____

4. Lab this week! Exploring genetics! Mitosis and meiosis Reproduction!
How we grow and how genes get into gametes!
Reproduction!
A paper-and-pencil activity where we “create” kids!
Genetic traits
Looking at ourselves!
Sampling bacteria for next week

5. Why do children look like their parents?
To answer this we’ll need to look at three things:
Where are genes?
How do animals grow?
How do animals produce gametes (sperm and eggs)?

6. Our genes are on chromosomes
Chromosomes are big packets of DNA
Each chromosome has many genes on it
Segments of DNA that code for a protein
PD image from:

7. Humans have 23 pairs of chromosomes
Note: this is a karyotype – an image of the chromosomes in a cell
PD image from:

8. So what’s the deal with genes?
We have two copies (ALLELES) of each gene (one on each chromosome)
These copies can either be different or the same
PD image from:

9. Some sample genes / alleles
Cystic fibrosis:
F = normal allele (healthy)
f = diseased allele
normal allele is dominant
Flower color in snapdragons
R = red flower
r = white flower
incompletely dominant

10. Mitosis: how cells divide

11. Cell division Mitosis: One cell to two cells Missing image:
Embryonic development series showing 1 cell to
gastrulation
Mitosis: prophase, prometaphase, metaphase, anaphase, telophase - from Wellcome images B , B ,
B , B , B Credit Benedict Campbell, Wellcome Images

12. Mitosis Homologous chromosomes Allele Sister chromatids
One cell:
Chromosomes replicate
Sister chromatids
One cell:
Mitosis (cells divide)
Two cells:
Each cell ends up with an identical set of chromosomes
i.e., One copy of each homologous chromosome
Art by Marc Perkins

13. OK, let’s do this ourselves
Let’s make some people!
Work through the first two steps of the handout
STOP when you get to meiosis

14. How do we reproduce?

15. Sperm and Egg
Sperm fertilizing egg - from Wellcome images B Credit Yorgos Nikas, Wellcome Images
Sperm and egg drawing - from Wellcome images N Credit Miles Kelly Art Library, Wellcome Images

16. How do we create our gametes?
Meiosis!
Production of haploid cells from diploid cells
Haploid = 1 copy of each chromosome
Diploid = 2 copies of each chromosome

17. Chromosomes replicate
Homologous chromosomes
One cell:
Meiosis
Chromosomes replicate
Sister chromatids
One cell:
First cell division
Sister chromatids
Two cells:
Second cell division
Four cells:
Art by Marc Perkins

18. OK, let’s now try all of this ourselves! Let’s make some people!

19. Directions for agar plates
Missing text:
Description of what to do with the agar plates.

20. Before you leave Clean up your work area
Show me your lab report so I can stamp it
Need to have all data fields filled in
Complete at home and then turn in at the beginning of next lab
Remember that we’ll have a quiz at the beginning of the next class
6-7 questions on today’s lab
3-4 questions on the lab we’ll do next week

21. Notes for the instructor:
I replaced the lab in the lab manual with one of my own design for this topic. My lab focused on walking students through mitosis and meiosis with paper models of chromosomes, and then using this modeling to introduce genetics (e.g., Punnett squares). Contact me if you’re interested in seeing this lab.
Add any relevant cleanup instructions to the final slide (that slide is a generic one I’m adding to each presentation).

22. License information
This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA.
The slides in this presentation were originally created by Marc C. Perkins (
You are free to use, modify, and distribute these slides according to the terms of the Creative Commons license (e.g., you must attribute the slides, no commercial uses are allowed, and future distributions must be licensed under a similar license).
Attribution should be given to Marc C. Perkins (and any later editors), including a link back to Marc’s current website. This applies both while distributing the slides and during use of the slides; attribution during use can be satisfied by, for instance, placing small text on at least one of the slides that has been shown (see below for an example).
Slides in this presentation based on those created by Marc C. Perkins.

23. History
August 2007: Marc Perkins released first version.
(If you modify these slides and redistribute them, add your information to the list)

24. Home-made mitosis and meiosis figures

25. Chromosomes replicate
Homologous chromosomes
One cell:
Meiosis
Chromosomes replicate
Sister chromatids
One cell:
First cell division
Sister chromatids
Two cells:
Second cell division
Four cells:
Art by Marc Perkins

26. Chromosomes replicate
Homologous chromosomes
Meiosis
One cell:
Chromosomes replicate
Sister chromatids
One cell:
First cell division
Two cells:
Sister chromatids
Second cell division
Four cells:
Art by Marc Perkins

27. Mitosis Homologous chromosomes Allele Sister chromatids
One cell:
Chromosomes replicate
Sister chromatids
One cell:
Mitosis (cells divide)
Two cells:
Each cell ends up with with an identical set of chromosomes
i.e., One copy of each homologus chromosome
Art by Marc Perkins

28. Extra Images

29. Chromosome
PD image from:

30. Human karyotype
PD image from:

31. Human karyotype
CC attribution image from:

32. Human karyotype
PD image from:

33. Mitosis
GFDL image from:

34. Mitosis
GFDL image from:

35. Mitosis
PD image from: