Meiosis-A prelude to reproduction. I.Terminology A.karyotype –1. human 46 –2. homologous pairs –3. diploid condition –4. note various sizes and shapes.

Meiosis-A prelude to reproduction

I. Terminology

• A. karyotype– 1. human 46

– 2. homologous pairs

– 3. diploid condition

– 4. note various sizes and shapes

– 5. genome

B. Chromatin

• 1. heterochromatin• 2. eucrhomatin• 3. 1.8 meters

C. Relationship between chromatin and chromosome

• 1. chromatin• 2. chromosomes• 3. histone proteins• 4. nucleosome

100µm

4. Scaffolding proteins

2µm

ScaffoldingProteins

DNA

5. Summary of chromosome complexity

C. Terms of chromosome structure

• 1. Dyad• 2. Centromere• 3. Sister chromatids

D. Homologous chromosome pairs

• 1. sister vs. nonsister chromatids

• 2. paternal vs. maternal• 3. genes vs. alleles

How many chromosomes do you see?

83%

17%

0%0%

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1. 42. 83. 104. No clue

E. Synapsis

1. Definition

2. Forms tetrads

3. Function-analogy of identical twins

4. Crossing over

5. Importance in evolution

F. Diploid vs. haploid

• 1. 2N vs. 1N• 2. Reproductive cells are haploid• 3. Why?• 4. Importance of meiosis

II. Meiosis overview

• A. Two separate divisions– Meiosis I reduction division– Meiosis II “mitotic-like”

division

• B. Where does it occur?– Animals– Plants

• C. What does meiosis produce?– Animals– Plants

III. Meiosis I

• A. Prophase I• B. Metaphase I• C. Anaphase I• D. Telophase I• E. End products

IV. Meiosis II

• A. Prophase II• B. Metaphase II• C. Anaphase II• D. Telophase II• E. Final products

V. Comparison between mitosis and meiosis

Event Mitosis Meiosis I Meiosis II

Synapsis occurs

Sister chromatids separate

Homologous chromosomes separate

Crossing over occurs

Tetrads form

Haploid cells form

Identical daughter cells form