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.

Today: Bellwork Part 5 Notes PTC Test

Materials Unit Book PTC Paper

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

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

Homework None 

Unit 6: Mendelian Genetics

Part V: Incomplete Dominance & Sex-Linked Traits

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

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

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

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

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

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

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

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

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

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 https://www.youtube.com/watch?v=bV6N1tLIPQA

Answer ?s in Note Guide

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