1. Chapter 7
PowerPoint by Jacob Rondinella

2. 7-1 The Human Genetic System
A good specimen to study genetics is the fruit fly Drosophila Melanogaster .
First studied the fruit fly  Why?
Thomas Hunt Morgan
It can produce a new generation in just a few weeks.
Fruit fly is small  and you could have many in a small area.
Simple genetic system  8 Chromosomes.

3. Male Drosophila Melanogaster

4. xy xx ♂ ♀ □ = ♂ (Male) ○ = ♀ (Female)
Karyotype - pictures of chromosomes grouped together
In a human Karyotype  22 pairs of chromosomes are homologous.
Homologous means similar in size, shape, and genetic content.
1 pair is your sex chromosomes
xy xx
♂ ♀
In order to study inheritance of human traits  Scientists create a family of history in the form of a pedigree chart. Fig 7-4 p. 149
Diagram that follows the inheritance or a single gene through several generations in a family.
□ = ♂ (Male)
○ = ♀ (Female)

5. Karyotype

6. Pedigree Chart

7. Dominant/Recessive Alleles Ex) Rh Blood group  Z alles
+ (Dominent)
- (Recessive)
Rh+ Rh+ Rh+ RH - } both show some Phenotype
Rh – Rh -  Shows reccome phenotype
Multiple Alleles  type of gene that is determined by more then two alleles.
EX) ABO Blood group  three Alleles Ia, Ib, i
Are codomijent over i
 the allele does not produce antigens

8. A - IA IA or IAi
B - IBIB or IBi
AB - IAIB
O - ii
Universal Rec. AB
Universal Donor O

9. 7-2 Sex-Linked Inheritance
23 pairs of chromosomes are found in somatic cells
22 pair are called autosomes  They are homologous
1 pair  sex chromosomes
Sex Linked= inheritance found only on the X or Y chromosome

10. Sex linked genes are almost always located on the X chromosomes.
Because males have just one X chromosomes, any X chromosome linked gene a male inherits, recessive or dominant is expressed.
Because males pass their X chromosomes along to their daughter  Sex linked genes will tend to move from father to daughter.

11. Color blindness – Inability to see certain colors.  10% of males in U
Color blindness – Inability to see certain colors.  10% of males in U.S. have colorblindness
♂  X Y comes from Dad
Comes from mom.
Hemophilia – Unable to produce one of the clotting factor proteins that helps blood to clot.
1/1000 Males
1/1,000,000 Females

12. Duchenne Musculer Dystropy - Sudden weakness of muscles because the body produces a defective protein  death will result
1/3000 males

13. 7-3 Human Genetic Disorders
Found on autosomes (22 pair) ablinism, Cystic Fibrosis Tay-Sachs, Sickle cell Anemia, PKU, Huntington.
Albinism –
Chrom 11 (recessive)
Unable to produce melanin (skin pigment for skin color)
Cystic Fibrosis- chromosome 7 (recessive)
Most common fatal genetic disease.
European ancestry – 1/2500
Defective protein that interferes with chloride ion movement. Thick heavy mucus in lungs.

14. Albino alligator

15. Tay-Sachs –
Fatal genetic disorder.
Common to Jewish families
Rapid breakdown of nervous system.
Sickle Cell Anemia -
Blood disorder where the blood cells look sickle shaped.
African ancestry
If you are a carrier of sickle cell, you are immune to malaria

16. PKU -
Phenylketonuria 1/15000 recessive
Will cause mental retardation
There is a test  if you have PKU as a baby  you are given a special diet.
Huntington Disease –
Dominant chrom 4
Symptoms occur in late 30’s – 40’s
Lose control of muscles
Takes 15 years to die.

17. Chromosome # Disorders
Non disjunction – chromosome pair fails to separate correctly during meiosis.
Abnormal numbers of chromosomes are produced in the sex cells.
Tuner Syndrome – a sperm or egg is produced without a sex chromosome XO  in zygote (45 chromosomes only)
Only females can be afflicted
Some organs do not develop
Other than not being able to have children, the person is fine.

19. Kline Feter Syndrome – Extra chromosomes (47)
XXY
Males  Underdeveloped sexual organs
Slight mental retardation
Down Syndrome –
Trisomy – nondisjunction on chrom 21
Extra copy of chrom 21
Heart/circ problems slight sever mental retardation.
47 chromosomes

20. Prenatal Testing Amni0centesis- taking fluid from the placenta
Chorionic Villus Sampling- tissue surrounding the fetus is removed and examined