Human Genetics and genetic disorders

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:”

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.

Another view…

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?