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ChromosomesChromosomesand and CellCell
ReproductionReproduction
The Cell Cycle
The cell cycle is a repeating sequence of cellular growth and division during the life of an organism.
A cell spends 90 percent of its time in the first three phases of the cycle.
CELL GROWTH
DNA SYNTHESIS
GROWTH & PREP. FOR MITOSIS
M PASE
G0 PHASE
A cell will enter the last two phases of the cell cycle only if it is about to divide.
key checkpoints at which feedback signals from the cell can trigger the next phase of the cell cycle (green light).
Cell Cycle Movie/Game
Overview of the cell cycle
Bacterial cells divide to reproduce
Binary fission is a form of asexual reproduction that produces identical
offspring: Mitosis
Chromosome Structure
ChromosomesChromosomes are the coiled are the coiled up version of DNA.up version of DNA.
They consist of DNA and They consist of DNA and proteins: proteins: histoneshistones and and nonhistonesnonhistones
How ChromosomesCoil
Each half of a chromosome is Each half of a chromosome is an exact copy called a an exact copy called a chromatidchromatid..
Chromatids are attached at the Chromatids are attached at the center called a center called a centromerecentromere..
A gene is a segment of DNA that codes for a protein or RNA molecule.
Cell TypesCell Types
Somatic CellsSomatic Cells
GametesGametes
Chromosome NumbersChromosome Numbers
Types: Autosomes and Sex Types: Autosomes and Sex Chromosomes (XX or XY).Chromosomes (XX or XY).
Humans: 22 pair of Humans: 22 pair of homologous chromosomes homologous chromosomes and 1 pair of sex and 1 pair of sex chromosomes.chromosomes.
Chromosome Numbers
All of the cells in the body, other than gametes are Diploid (2n=46 in humans).
Gametes contain only one set of chromosomes: Haploid (n=23 in humans).
Different species have Different species have different numbers of different numbers of chromosomes.chromosomes.
Change in chromosome number
Humans who are missing even one of the 46 chromosomes usually do not survive.
Humans with more than two copies of a chromosome, result in a condition called trisomy.
Abnormalities in chromosome number can be detected by analyzing a karyotype.
Nondisjunction during the production of gametes results in gametes having more or less chromosomes than normal.
Pictures called karyotypes can detect problems after conception.
Karyotypes Explained
When control is lost: cancer
Cancer is the uncontrolled growth of cells.
Mutations in genes that control cell division may result in cancer.
Cancer Biology
All the Details
The Phases of MitosisThe Phases of MitosisInterphaseInterphase
ProphaseProphase
MetaphaseMetaphase
AnaphaseAnaphase
TelophaseTelophaseCytokinesis Cytokinesis
II PPrefer refer MMy y AAwesome wesome TTeacher…eacher…CCool!ool!
MITOSIS
The Jazzy Version of
Mitosis
ProphaseProphase1.Chromosomes
coil and become visible.
2.Nuclear envelope & nucleolus breaks down.
3. Mitotic Spindle fibers begin to form.
MITOTIC SPINDLE
CENTRIOLES
CENTROMERE
NUCLEAR ENVELOPE
HOMOLOGUES
MetaphaseMetaphase 1.Chromosomes
line up along the equator of the cell.
2.Spindle fibers attach to kinetochore.
3.Centrioles migrate to the poles of the cell.
AnaphaseAnaphase
1.Spindle fibers begin to shorten.
2.Chromatids separate.
3.Chromatids begin moving toward the poles of the cell.
TelophaseTelophase1.Nuclear envelope reforms.
2.Cleavage furrow forms pinching the cytoplasm.
3.Chromosomes uncoil.
4.Cytokinesis begins.
Cytokinesis
During telophase, cytokinesis occurs.
During cytokinesis, the cytoplasm of the cell is divided in half, and the cell membrane grows to enclose each cell.
Cleavage In
Action
MeiosisMeiosisUSA 300,000,000 strong and growingUSA 300,000,000 strong and growing
Meiosis produces gametes and Meiosis produces gametes and reduces the number in chromosomes reduces the number in chromosomes in half.in half.
The following presents mitosis on the The following presents mitosis on the left and the corresponding meiosis left and the corresponding meiosis phase on the right….notice the phase on the right….notice the differences.differences.
First Link First
Prophase Prophase IProphase Prophase IGENTEIC RECOMBINATION
INDEPENDENT ASSORTMENT
SYNAPSIS
Metaphase Metaphase IMetaphase Metaphase I
Anaphase Anaphase IAnaphase Anaphase I
Telophase Telophase I Telophase Telophase I
& Cytokinesis & Cytokinesis I & Cytokinesis & Cytokinesis I
None Prophase II None Prophase II
None Metaphase IINone Metaphase II
None Anaphase IINone Anaphase II
None Telophase II None Telophase II
& Cytokinesis II& Cytokinesis II
Formation of GametesFormation of Gametes
SpermatogenesisSpermatogenesis
spermatids
OogenesisOogenesis
OVUM
Third LinkComparison ofOOGENESIS
&SPERMATOGENISIS
So How Do Mitosis and Meiosis So How Do Mitosis and Meiosis Compare?Compare?
..
Comparison of Mitosis and Meiosis
Types of ReproductionTypes of Reproduction
Sexual and AsexualSexual and Asexual
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