Topic+3

**Heredity and the source of variation**
Here's an [|epigenetics activity] you can try at home! || Errors in Meiosis and Crossing-Over HW: Non-disjunction & [|Genes&Blood Type] || HW: Read on [|Meiosis](all modules) & [|Using Karyotypes page] || Sample for the "Human Traits Survey" ||
 * [[image:bpenewb.gif]] || 4/25: Incomplete Dominance; Multiple alleles, Cancer & Epigenetics Review; Introduce DNA Structure (Homework) ||
 * || 4/22: Review Cancer Genetics; Introduction to [|Epigenetics]; HW: Read [|DNA Is Not Destiny _ Living World _ DISCOVER Magazine.pdf] Answer these questions (I'll collect them) [|DNAisnotDestinyArticlequestions_000.doc]
 * || 4/20: Quiz-Meiosis and Basic Inheritance; Go Over Blood Typing & Incomplete Dominance; Introduce "[|Cancer and Heredity]" ||
 * || 4/16 Blood-type Lab HW: Finish blood type lab analysis. Quiz on Monday: Meiosis and Basic Inheritance ||
 * || 4/14 Meiosis Stages in more detail, check foldable notes. Segregation & Independent Assortment (Mendel Intro).
 * || 4/10:Introduction to Meiosis; Check out [|Meiosis animation] and create a "foldable".
 * || 4/8: Heredity basics and problem-solving. HW: Monohybrid problems ||
 * || 4/3: Traits intro and coin toss lab. ||
 * || 4/1: Complete the[| Tour of the Basics: //What is a Trait?//]

**__Enduring Understandings__**

 * **Inheritance is controlled by the expression of genes and their interaction with the environment.**
 * **Variation is the result of mutation and genetic recombination through sexual reproduction.**
 * **Most traits are controlled by complex patterns of inheritance.**
 * **The effects of mutations can be beneficial, harmful, or neutral and depend on environmental pressures.**
 * **Several factors including genetic drift and natural selection affect the relative frequencies of traits between populations.**

Meiosis Notes:

Purpose: To produce sex-cells (gametes) with half of the organism's genetic information. For examples, in human beings (46 chromosomes), sperm and eggs are created through Meiosis and have 23 chromosomes each.

Why is it important? -Meiosis = Genetic recombination -Sexual Reproduction with conservation of chromosome numbers. (i.e., if meiosis didn't exist, human's chromosomes would double each generation: 46, 92, 184, etc.)

Where does Meiosis take place? -Males -> Testes -Females -> Ovaries

When does it take place? -Males -> Puberty until slightly after death -Females -> Starts in the mother's womb. Process suspended when baby reaches fetal stage. Meiosis resumes at puberty and ends at menopause. (Menopause exists to prevent older women from getting pregnant, because the older the person, the higher the chance of irregular meiosis resulting in birth defects. Also, older women have a higher chance of death due miscarriage.)

How does it take place? Phases: -interphase -prophase 1 -metaphase 1 -anaphase 1 -telophase 1 -prophase 2 -metaphase 2 -anaphase 2 -telophase 2

(I didn't really get much down for the "How" bit, so if anyone else has anything to add or change to the notes in general, feel free to do so. -Shang)

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