392 - Chapter 11-4 Outline : Meiosis (pp. 275 – 278)
The word "meiosis" comes from the Greek meioun, meaning à______since it results in a à______.
I. Meiosis
A. Why is Meiosis important?
Consider these questions …
1. How many chromosomes would a human sperm or an egg contain if either one resulted from the process of mitosis?
a. à______
2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo?
b. à______
______
3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have?
c. à______
*Meiosis à______*
B. Chromosome number
1. à______
a. Ex: turkey à ______, fruit fly à ______, human à______
2. Organisms that reproduce sexually have pairs of similar chromosomes
a. Called à ______
b. Similar in size, structure, and carry genes for the à ______
(but may be different forms of the gene)
c. Each member of a pair comes from à______
d. Ex: humans have à ______of homologous chromosomes,
or à ______total
i. à ______in sperm, à ______in egg, pair up
3. Diploid vs. haploid
a. Diploid
i. à ______set of chromosomes
ii. à ______
iii. Humans – 23 sets/pairs, à ______
b. Haploid
i. à ______set of chromosomes
ii. à ______
iii. Humans – one chromo. from each set, à ______
4. Chromosome numbers & cell types
a. Somatic cells
i. à______
ii. à ______
iii. Humans à ______
b. Gametes
i. à______
ii. Usually egg & sperm (or pollen/spores)
iii. à ______
iv. Humans à ______
C. Phases of Meiosis
Meiosis I
1. Interphase I
a. Cells undergo a round of à ______
______
2. Prophase I
a. Each chromosome pairs with its corresponding homologous
chromosome to form a à ______
i. tetrad à ______
b. Homologous chromosomes exchange portions of their chromatids
ii. à ______
3. Metaphase I
a. à ______attach to the chromosomes
b. Tetrads line up in the à ______
4. Anaphase I
a. Fibers pull homologous chromosomes toward à ______
______
b. Centromere à ______
5. Telophase I and Cytokinesis
a. à ______form
b. Cell separates into à ______
Meiosis II
1. Prophase II
a. Meiosis I results in à ______each with
à ______the number of homologous chromosomes as the original
cell
2. Metaphase II
a. Chromosomes line up in the à ______
3. Anaphase II
a. Paired à ______separate and move towards
à ______
b. Centromere à ______
4. Telophase II and Cytokinesis
a. Meiosis II results in à ______
b. Each cell contains à ______the # of chromo. as the original cell
D. Gamete Formation
E. Comparing Mitosis and Meiosis
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