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Human Geneticsand genetic disorders
If we were to crack open ANY one of your non-gamete cells…
If we were to crack open ANY one of your non-gamete cells…
These chromosomes contain all of your 20,000 to 25,000 of your genes
Which if organized looks like
Quick quiz
• Is this a boy or a girl?
• What phase of the cell cycle is shown in the circle?
• What phase is the cell in when the chromosomes look like they do in the box?
• Is this a boy or a girl?
• What phase of the cell cycle is shown?
Key terms
• Karyotype• Sex chromosomes vs. autosomes• Gamete vs. somatic cell
X-chromosome inactivation• Why is this necessary?
Polygenic traits
• Height inheritance is not as straightforward, as it is inherited by multiple genes working together.
Blood type is a unique trait in that there are three alleles, two of which are co-dominant
Genetic Disorders
Single gene mutations
• Can be either on an autosome or a sex chromosome– The latter would be termed sex-linked– Why is this a huge disadvantage to males?
What is atypical about this person?
Chromosomal mutations
• Result from non-disjunction during anaphase I
Pedigree charts
• Show passage of a given trait through a family.– They reveal mode of inheritance
= Huntington’s Disease
1. How many girls did II-1 and II-2 have? How many have Huntington’s Disease?
2. How are individuals III-2 and II-4 related? I-2 and III-5?
3. How many children did individuals I-1 and I-2 have?
4. There are no carriers for Huntington’s Disease- you either have it or you don’t. With this in mind, is Huntington’s disease caused by a dominant or recessive trait?
5. Is this disease on x-chromosome, y-chromosome, or on an autosome?
Describe the “mode of inheritance:”
Describe the “mode of inheritance:”
Hemophilia, the royal disease• Hemophilia is a hereditary bleeding disorder.• Caused by a recessive gene on the X chromosome.
• There are about 20,000 hemophilia patients in the United States.
• The severity of hemophilia is related to the amount of the clotting factor in the blood. About 70% of hemophilia patients have less than one percent of the normal amount and, thus, have severe hemophilia.
Color Blindness
• 1/10 males have, 1/100 females have. Why the difference?
• Individuals are unable to distinguish shades of red-green, usually, sometimes purple or blue.
• Are you color blind?