CELL REPRODUCTION Chapter 8 CHROMOSOMES CELL DIVISION MEIOSIS.
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8 Notes November 01, 2011
8 Cell ReproductionSection 1 ChromosomesSection 2 Cell DivisionSection 3 Meiosis
8-1 ChromosomesObjectives
Describe the structure of a chromosome.
Identify the differences in structure between prokaryotic chromosomes and eukaryotic chromosomes.
Compare the numbers of chromosomes in different species.
Explain the differences between sex chromosomes and autosomes.
Distinguish between diploid and haploid cells.
Chromosome StructureChromosomes are rod-shaped structures made of DNA and protein.
In eukaryotes, DNA wraps around proteins called histones to help maintain the compact structure of chromosomes.
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Chromosome Structure
Chromosome structure, continued
Chromosomes in prokaryotes are simpler in structure than chromosomes in eukaryotes.
Chromosome Numbers
Each species has a characteristic number of chromosomes in each cell.
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Number of chromosomes in various organisms
Sex Chromosomes and Autosomes
Sex chromosomes are chromosomes that determine the sex of an organism.
All of the other chromosomes in an organism are autosomes.
Chromosome numbers, continued
Diploid and Haploid Cells
Cells having two sets of chromosomes are diploid (2n).
Haploid cells (1n) have only one set of chromosomes.
Chromosome numbers, continued
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8-1 Study Guide
8 Notes November 01, 2011
8-2 Cell Division
Describe the events of cell division in prokaryotes.
Name the two parts of the cell that are equally divided during cell division in eukaryotes.
Summarize the events of interphase.
Describe the stages of mitosis.
Compare cytokinesis in animal cells with cytokinesis in plant cells.
Explain how cell division is controlled.
Objectives
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Cell division is the process by which cells reproduce themselves.
Cell division in prokaryotes
Binary fission is the process of cell division in prokaryotes.
Cell division in prokaryotes, continued
Cell Cycle
The cell cycle is the repeating set of events in the life of a cell. The cell cycle consists of cell division and interphase.
Cell Division in Eukaryotes
Cell division in eukaryotes includes nuclear division, called mitosis, and the division of cytoplasm, called cytokinesis.
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InterphaseInterphase consists of growth (G1), DNA replication, and preparation for cell division (G2).
Cell Division in Eukaryotes, continued
Stages of Mitosis
Mitosis is divided into stages: prophase, metaphase, anaphase, and telophase.
Mitosis results in two offspring cells that are genetically identical to the original cell.
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Stages of Mitosis, continued
Cytokinesis
During cytokinesis in animal cells, a cleavage furrow pinches in and eventually separates the dividing cell into two cells.
In plant cells, a cell plate separates the dividing cell into two cells.
Control of Cell Division
Cell division in eukaryotes is controlled by many proteins.
Control occurs at three main checkpoints.
When Control is Lost: Cancer
Cancer may result if cells do not respond to control mechanisms.
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8-2 Study Guide
8 Notes November 01, 2011
8-3 MeiosisObjectives
Compare the end products of meiosis with those of mitosis.
Summarize the events of meiosis I.
Explain crossing-over and how it contributes to the production of unique individuals.
Summarize the events of meiosis II.
Compare spermatogenesis and oogenesis.
Define sexual reproduction.
Formation of Haploid Cells
Meiosis is a process of nuclear division that reduces the number of chromosomes in new cells to half the number in the original cell.
Meiosis produces haploid gametes.
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Meiosis is a process of nuclear division that reduces the number of chromosomes in new cells to half the number in the original cell.
Meiosis leads to four haploid cells (gametes) rather than two diploid cells as in mitosis.
Formation of Haploid Cells, continued
Meiosis I
Meiosis I includes prophase I, metaphase I, anaphase I, and telophase I.
Crossing-over, which is when portions of homologous chromosomes exchange genetics material, occurs during prophase I and results in genetic recombination.
Meiosis I
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Meiosis IIMeiosis II includes prophase II, metaphase II, anaphase II, and telophase II.
Four new haploid cells result.
Stages of Meiosis
Development of Gametes
Spermatogenesis is the process by which sperm cells are produced.
Oogenesis is the process that produces mature egg cells.
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Meiosis in Male and Female Animals
Sexual Reproduction
Sexual reproduction is the formation of offspring through meiosis and the union of a sperm and an egg.
Offspring produced by sexual reproduction are genetically different from the parents.
8-3 Study Guide
8 Notes November 01, 2011
8 Notes November 01, 2011
Additional Instructor's Notes from previous explanations.
8 NotesCell Reproduction8-1 Chromosomes
when?histones - structure. Like a bobbin, spindle, or spool
✓
Function - non-histones
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ChromatidCentromereChromatin
Dipoid Number of 2: Cell during S phase of Interphase. DNA is copied (red chromatids)
Prophase of Mitosis: Chromatin shortens, coils, and thickens. Becomes chromosomes.
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MoreBetter?
Sex chromosomes
autosomes
do not confusewith sex cells.
X Y
Sex Chromosomes
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homologous pairs of chromosomes
fertilization
zygoteegg
sperm
Same size, shape, and the type of information they carry
Karyotype23 pair of chromosomes in humans
1 pair-Sex Chromosomes
22 pair of autosomes
diploid
haploid
2n
1n Sex Cells
Somatic Cells
What are these numbers in Humans?
1 N = 23
2 N=46
erase below!
PaternalMaternal
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8-1 Review
8-2 Cell DivisionProkaryotes
Binary fissionBacteria
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Cell Cycle
m Phase
Mitosis
Meiosis
- results in 2identical nuclei.
-how sex cells aremade. 1/2 DNA (from each homologous chromosome) ends up in each nucleus
asexual
asexual
sexual-union ofGametes
-clones?Identical Genetically) offspring
Sperm egg zygote
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P M A TP Prophase
MITOSIS4 phases
Metaphase
Anaphase
Telophase
AM
T
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Prophase
-
1. TAKE THE FENCE DOWN (NUCLEAR MEMBRANE)2. SHORTEN, COIL AND THICKEN3. CENTROSOMES APPEAR - ANCHORS4. ROPES (SPINDLE FIBERS)KINETECHORE AND POLAR FIBERS
Metaphasechromosomes line up at mid line
AnaphaseChromatids separate
spindle fibers (kinetechore) shorten
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Telophase: opposite events of prophase
Cleavage furrow
After M phase, cytokinesis follows
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Mitosis
Go - cells exit cell cycle. Still alive, but do now divide anymore
Cells are idle.
Cancer- loss of control
of cell cycle.
Carcinogen - cancer causing agent
.
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8-2 Review
8-3 Meiosis
Meiosis - Meiosis I
metaphase I
synapsis -homolgous chromosomes line up
tetrad - resulting shape of the four chromatids of the two homolgous pair
Crossing Over - results in increased genetic diversity
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Crossing Over occurs when chromosomes that make a a tetrad exchange portions of their chromatids during synapsis. Crossing over results in an exchange of genes and in new contibinations of genes.
anaphase I
telophase I
IndependentAssortment
and Cytokinesis
Meiosis II
ChromatidsSeparate
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telophase II
Cytokinesis
4 haploid offspring
spermatogenesis
Immature sperm are spermatids
oogenesis.
1 Egg (haploid)
3 Polar Bodies
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each symbol represents a pair of homologous chromosomes. This cell is therefore diploid
"S" phase of interphase
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The cell has just divided
anything wrong?
Telophase, followed by cytokinesis
Meiosis I
Meiosis II
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8-3 Section Review
8 Notes November 01, 2011