meiosis and human genetics. outline of the day 1.turn in your lab reports at the front –more than...
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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
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