1. Bellwork: 3/7 Put your phone up  Week 3/4 - 3/8
Males & females have different sex chromosome (X & Y). Do you know what sex chromosomes females have?
Males?
Explain the difference between dominant, recessive, and codominance.

2. Today:
Bellwork
Part 5 Notes
PTC Test

3. Materials
Unit Book
PTC Paper

4. This Week: Monday: Monster Tuesday: Part 4 Notes
Wednesday: Blood Typing Packet
Thursday: Part 5 Notes & PTC
Friday: PS Review & Movie

5. Next Week: Monday: Movie Tuesday: Study Guide
Wednesday: Kahoot & Review
Friday: Test

6. Homework
None 

7. Unit 6: Mendelian Genetics

8. Part V: Incomplete Dominance & Sex-Linked Traits

9. Incomplete Dominance
Definition: When one allele is not completely dominant over the other
Common in plants, as well as, animal/human skin color & hair color
Mixing of the alleles

10. Human Chromosomes Humans have 23 pairs of chromosomes
1-22 chromosome pairs
Are autosomal chromosomes (not related to gender)
23rd chromosome pair are the sex chromosomes
XX = female
XY = male

12. Sex-Linked Disorders Very few genes found on the Y chromosome
Most genes on the Y chromosome associated with maleness (male reproductive organs)
More than 100 have now been mapped

13. Role of Father in Passing of Sex-Linked Traits
Father determines gender
Donates Y chromosome to sons
Donates X chromosome to daughters
Fathers cannot pass sex-linked traits
So the mother passes sex-linked traits

14. Role of Mother
Pass sex-linked alleles (X) to both daughters and sons

15. Sex-Linked Traits More Common in Males
Females have fewer sex-linked disorders because…
It only shows up if homozygous recessive
Females have two X chromosomes
Males have only one X chromosome
If they have one disorder allele then they have the disorder
More common to have sex-linked disorders

16. Common Sex- Linked Disorders
Color Blindness
Most commonly red-green color blindness
X-linked recessive disorder
Individuals with this color blindness see fewer than 25 colors
Results from some or all of the receptors that respond to red and green being weakened or absent

17. Common Sex- Linked Disorders
Hemophilia A
Causes lack of blood clotting
X-linked recessive disorder
Symptoms
Tend to bruise easily
Internal bleeding can cause problems with muscles & joints

18. Common Sex- Linked Disorders
Duchenne Muscular Dystrophy
Disease that results in the progressive weakening of skeletal muscles
X-linked recessive disorder

19. Common Sex- Linked Disorders
Fragile X Syndrome
Attributed to autism and mental retardation
Causes large protruding eyes, ears and an elongated face
X-linked recessive disorder

20. Answer ?s in Note Guide

21. PTC Gene Taster (dominant) vs. Non-taster (recessive)
PTC gene codes for a taste receptor on the tongue
Tasters have the evolved gene of tasting bitter compounds
Most toxins in the environment are bitter which has led to the evolution of the PTC gene to detect the toxins