Which animal will stay warm longer, a mouse or an elephant?

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Define in your own words (p. 275) Meiosis Diploid Haploid Gamete Crossing Over Chromosomes

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Daily Question

Draw a chromosome. Explain what a chromosome is.

Why is crossing over important?

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Eukaryotic Chromosomes

All eukaryotic cells store genetic information in chromosomes

Human body cells have 46 chromosomes or 23 identical pairs

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Chromosomes in Dividing Cells

Two sides of a chromosome are called chromatids & are held together by the centromere

5Called Sister Chromatids

Chromosome Structure

Chromosomes contain DNA and Protein packed together to form chromatin.

Chromatin is made of DNA that is wrapped around the protein, histones.

Histone and DNA forms clusters called nucleosomes.

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Boy or Girl?

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Y - Chromosome

X - Chromosome

The Y Chromosome Decides

Daily Question

Explain the differences between homologous chromosomes and sister chromatids.

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Cell Reproduction

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MeiosisFormation of Gametes (Eggs & Sperm)

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Facts About Meiosis Two meiotic divisions ---

Meiosis I and Meiosis II

Original cell is diploid (2n)

Four daughter cells produced that are haploid (1n)

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Meiosis: Two Part Cell Division

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Homologsseparate

Sister chromatidsseparate

Diploid

Meiosis I

MeiosisII

Diploid

Haploid

Meiosis I: Reduction Division

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Nucleus Spindlefibers Nuclear

envelopeEarly Prophase I(Chromosome number

doubled)

Late Prophas

e I

Metaphase I Anaphas

e ITelophase I (diploid)

Interphase

Before Meiosis Begins DNA replication occurs

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Nucleus

Prophase I

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Crossing over occurs- homologous chromosome- Form Tetrad

Tetrads Form in Prophase I

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Homologous chromosomes

(each with sister chromatids)  

Join to form a TETRAD

Crossing-Over

Pieces of genes are exchanged

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Homologous Chromosomes During Crossing-Over

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1. Crossing-over occurs during:A. anaphase 1 B. Metaphase 1C. Prophase 1 D. Prophase 22. Which of the following cells undergo meiosis?A. Sperm Cells B Liver CellsC. Unicellular organismsD. All of the above

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Quiz Explain all parts of a

chromosome, in words and drawings.

Define diploid, chromatin, sister chromatids, and centromere. Extra Credit: What phase is

technically not part of meiosis? Why?

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Metaphase I

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Homologous pairs of

chromosomes align along the equator of the

cell

Anaphase I

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Homologs separate and move to opposite poles.

Sister chromatids remain attached at their centromeres.

Break

What is the difference between Metaphase and Anaphase?

What is the job of the centrioles?

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Telophase I

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Nucleus reassembles.

Spindle fibers disappear

Cytokinesis divides cell into two.

Break

What is the difference between Interphase and Prophase?

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Daily Question

Explain what occurs in Meiosis I, in your own words.

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Meiosis II

Only one homolog of each chromosome is present in the cell.

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Meiosis II produces gametes with one copy of each chromosome and thus one copy of each gene.

Sister chromatids carry identical genetic information.

Gene X

Meiosis II: Reducing Chromosome Number

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Prophase II

Metaphase II

Anaphase II

Telophase II 4 Identical

haploid cells

Prophase II

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Nuclear envelope disappears.

Spindle forms.

Half the number of chromosomes as original in each cell

Break

What is the difference between Prophase I and Prophase II?

What is the difference between the cells at the end oogenesis and spermatogenesis?

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Daily Question

At the very end of meiosis II each cell has 23 chromosomes.

How many chromosomes are created during Interphase?

How many chromosomes does the cell have at the very start of Prophase I?

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Metaphase II

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Chromosomes align along equator of cell.

Anaphase II

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Sister chromatids separate and move to opposite poles.

Equator

Pole

Break

What is the difference between Anaphase I and Anaphase II?

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Telophase II

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Nuclear envelope assembles.

Cytokinesis II

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Gametes (egg & sperm) form

Four haploid cells with one copy of each chromosome

Different combinations of different genes

Hybrid offspring

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Meiosis results in _____A. 2 haploid daughter cells B. 4 haploid

daughter cellsC. 2 diploid daughter cells D. 4 diploid

daughter cells

The picture depicts what stage of meiosis?        

A. Prophase 1 B. Anaphase 1

C. Metaphase 1 D. Metaphase 2

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Name of Process in Gametes

Egg: OogenesisFormation of 1 true egg and 3 polar bodies

Sperm: SpermatogenesisFormation of 4 true sperm cells 39

Winter Break Extra Credit

Make an information pamphlet about one specific genetic diseases. The following must be included:

What is the disease? What does the disease do to the body it is affecting?

When was the disease discovered? Who discovered it? What type of mutation causes the disease? What are the tests to see if a person has the disease? How many people get this disease? Any other important information people need to know

about the disease. Pictures

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Holiday Science

Friday December 19, 2008 Bring some food to share with the class.

It can be anything you enjoy!

If you don’t bring something you can’t eat anything!

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