meiosis and human genetics

Meiosis and Human Genetics

Outline of the day

1. Turn in your lab reports at the front– More than 10 minutes late = bad

2. Any questions on last week’s lab?

3. Quiz

4. Introduction to the lab

5. Lab!

6. 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

• 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 divisionMitosis: 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

• Each cell ends up with an identical set of chromosomes– i.e., One copy of each homologous chromosome

Homologous chromosomes

Chromosomes replicate

Sister chromatids

Mitosis (cells divide)

Two cells:

One cell:

One cell:

Allele

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

MeiosisHomologous chromosomes

Chromosomes replicate

Sister chromatids

First cell division

Two cells:

One cell:

One cell:

Sister chromatids

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

MeiosisHomologous chromosomes

Chromosomes replicate

Sister chromatids

First cell division

Two cells:

One cell:

One cell:

Sister chromatids

Second cell division

Four cells:

Art by Marc Perkins

MeiosisHomologous chromosomes

Chromosomes replicate

Sister chromatids

First cell division

Two cells:

One cell:

One cell:

Sister chromatids

Second cell division

Four cells:

Art by Marc Perkins

Mitosis

• Each cell ends up with with an identical set of chromosomes– i.e., One copy of each homologus chromosome

Homologous chromosomes

Chromosomes replicate

Sister chromatids

Mitosis (cells divide)

Two cells:

One cell:

One cell:

Allele

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