Download Cell Division.notebook

Cell Division.notebook
September 23, 2015
Chromosomes &
Cell Division
(Cell Reproduction)
I. Formation of New Cells by Cell Division
A. Prokaryotic Cell Reproduction
Asexual Reproduction ­ Binary Fission
(identical offspring ­ DNA is the same!)
Bacteria
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B. Eukaryotic Cell Reproduction
Gene ­ Segment of DNA that codes for a protein
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II. How does chromosome number and structure affect development?
Somatic cell → body cell
Gamete cell → sex cell (sperm or egg)
A. Sets of Chromosomes
Homologous Chromosomes ­ a set or pair of chromosomes that are the same size, shape, and genetic content (DNA)
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Diploid ­ Somatic cells with 2 sets of chromosomes (2n)
Haploid ­ Sex cells with 1 set of chromosomes (n)
Human somatic cell (2n) ­ 46
Human sex cell (n) ­ 23
What is fertilization?
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Egg (____)
+
Sperm (____)
=
Zygote (_____)
Chromosome Numbers of Various Organisms
2n (diploid)
Organism
Mosquito
6
10
Corn
Adder's Tongue Fern
n (haploid)
1,020
Frog
13
Orangutan
24
Dog
78
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B. Sex Chromosomes
1. Autosomes ­ chromosomes that do not determine sex/gender of an organism
2. Sex Chromosomes ­ chromosomes that determine sex/gender of an organism
*The male determines the sex of the child!
Exceptions: 1. Grasshoppers (no Y chromosome)
females ­ XX
males ­ XO
2. Birds, Moths, & Butterflies
females ­ XO
males ­ XX
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C. Change in Chromosome Number
Karyotype ­ picture of chromosomes
How do you make a karyotype?
Boy or Girl???
How are karyotypes used by geneticists?
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C. Change in Chromosome Structure
Mutation Activity
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Mitosis ­ cell division of somatic cells
*Asexual Reproduction
*End product ­ 2 daughter cells
that are genetically identical
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Interphase
*A cell is in this phase 90% of the time
*DNA is replicated
*Busiest phase
*G1, S, & G2 portion of cell cycle
Mitosis ­ division of the nucleus
*Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
Prophase
*Chromosomes become visible
*Centromeres connecting sister chromotids
*Spindle fibers forming
*Nuclear envelope is disappearing
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Metaphase
*Sister chromatids line up in the
middle (at the equator)
Anaphase
*Centromeres break apart & spindle
fibers pull sister chromatids to
opposite poles
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Telophase & Cytokinesis
*Last phase of mitosis
*Nuclear membrane reforms
*Cytoplasm divides (cytokinesis)
*Two daughter cells formed that are genetically identical
*Chromosomes turn back into chromatin
*Cell plate forms in plant cells & develops into cell wall
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Meiosis ­ cell division of sex cells
(gametes ­ egg & sperm)
Males ­ Spermatogenesis
*Occurs in testes
*End product is 4 cells (sperm) with half the
number of chromosomes as the parent cell
Female - Oogenesis
*Occurs in ovaries
*End product in females is 1 cell (egg) with half the
number of chromosomes as the parent cell & 3 polar
bodies that are wasted (not used)
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Phases of Meiosis
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Review Sites
http://www.pbs.org/wgbh/nova/miracle/divi_flash.html
http://www.cellsalive.com/
The End of Today's Lesson!
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Homework: Phases of Mitosis
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1
5
19
12
23
30
22
36
49
37
62
50
73
63
1. Identify each phase of mitosis occurring within each cell.
2. Determine the percentage of each phase. (# of phase/total of all phases x 100)
3. Which phase has the highest percentage? Explain how this relates to the overall cell cycle.
Interphase Prophase Metaphase Anaphase Telophase
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Mitosis Lab
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