Meiosis and Human Genetics

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

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

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

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)?

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: http://www.genome.gov/Pages/Hyperion/DIR/VIP/Glossary/Illustration/chromosome.cfm?key=chromosome

Humans have 23 pairs of chromosomes Note: this is a karyotype – an image of the chromosomes in a cell PD image from: http://en.wikipedia.org/wiki/Image:NHGRI_human_male_karyotype.png

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: http://en.wikipedia.org/wiki/Image:NHGRI_human_male_karyotype.png

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

Mitosis: how cells divide

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 http://images.wellcome.ac.uk/ B0004174, B0004175, B0004176, B0004177, B0004178 Credit Benedict Campbell, Wellcome Images

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

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

How do we reproduce?

Sperm and Egg Sperm fertilizing egg - from Wellcome images http://images.wellcome.ac.uk/ B0002107 Credit Yorgos Nikas, Wellcome Images Sperm and egg drawing - from Wellcome images http://images.wellcome.ac.uk/ N0027724 Credit Miles Kelly Art Library, Wellcome Images

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

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

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

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

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

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).

License information This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/us/ 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 (http://faculty.orangecoastcollege.edu/mperkins). 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. http://faculty.orangecoastcollege.edu/mperkins

History August 2007: Marc Perkins released first version. http://faculty.orangecoastcollege.edu/mperkins (If you modify these slides and redistribute them, add your information to the list)

Home-made mitosis and meiosis figures

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

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

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

Extra Images

Chromosome PD image from: http://www.genome.gov/Pages/Hyperion/DIR/VIP/Glossary/Illustration/chromosome.cfm?key=chromosome

Human karyotype PD image from: http://en.wikipedia.org/wiki/Image:NHGRI_human_male_karyotype.png

Human karyotype CC attribution image from: http://en.wikipedia.org/wiki/Image:PLoSBiol3.5.Fig7ChromosomesAluFish.jpg

Human karyotype PD image from: http://en.wikipedia.org/wiki/Image:Sky_spectral_karyotype.gif

Mitosis GFDL image from: http://en.wikipedia.org/wiki/Image:Chromosomes_during_mitosis.svg

Mitosis GFDL image from: http://en.wikipedia.org/wiki/Image:Chromosomes_during_mitosis.svg

Mitosis PD image from: http://en.wikipedia.org/wiki/Image:MajorEventsInMitosis.jpg