Bellwork 37 Put your phone up Week 34
Bellwork: 3/7 Put your phone up Week 3/4 - 3/8 1. 2. 3. 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: 1. Bellwork 2. Part 5 Notes 3. 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) • 23 rd 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 sexlinked 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=b. V 6 N 1 t. LIPQA
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
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