cell cycle. cell theory: * all living things composed of cells * cells are the basic units of...
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BIOLOGY 1Cell Cycle
Cell Review
Cell Theory:
* All living things composed of cells
* Cells are the basic units of structure and function in living things.
* New cells are produced from existing cells
Cell Review
Nucleus of the Cell:Controls most cell processes and contains the hereditary information. This is found as Deoxyribonucleic Acid (DNA)
Chromatin: DNA bound to protein – granular and visible in the nucleus.Chromosomes: Chromatin that condenses in preparation for cell division.DNA: Coded instructions for making proteins.
Cell Review
Microtubules: They aide in cell division, separating chromosomes (known as centrioles in animal cells).
Cell Division
PROKARYOTE CELL DIVISION
EUKARYOTE CELL DIVISION
Asexual Reproduction Growth and replacement of old and/or dying cells
DNA = One Circular Chromosome and Plasmids
DNA = 10-50 chromosomes per cell
Humans = 46 (23 identical pairs)
Cell Division called the Cell CycleCell Division called Binary Fission
Cell ReplicationCell Cycle:
Phase 1: Interphase
Phase 2: Mitosis
Phase 3: Cytokinesis
G1 - primary growth phaseS – synthesis; DNA replicatedG2 - secondary growth phase
Cell Replication (Cell Cycle)
Phase 1: InterphaseG1 - primary growth phase
S – synthesis; DNA replicated
G2 - secondary growth phase
Cell Matures: Growth and Organelles
DNA copied/replicated
Cell Structures needed for division made Centrioles
Mitosis: Prophase
Chromatin condenses into chromosomes Mitotic spindle forms and attaches to
centromeres Nuclear membrane/nucleolus broken
down.
Mitosis: Prophase
dissolving
Centrioles
Mitosis: Metaphase
Chromosomes line up at the equator of the cell
Mitosis: MetaphaseCentriole
Centriole
CentromereEquator
Mitosis: Anaphase
Sister Chromatids pulled apart to opposite poles of the cell.
Anaphase
Equator
Review
Mitosis: Telophase
Sister Chromatids completely at opposite poles
Nuclear envelope forms Nucleolus appears Cytokinesis occurs
Mitosis: Telophase
Equator
Cell Replication (Cell Cycle)
Phase 3: Cytokinesis
Division of cell into two – Division of the cytoplasm by a
cleavage furrow
Cleavage Furrow
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Name the Stages of Mitosis:
Interphase
Early prophase
Mid-ProphaseLate Prophase
Metaphase
Late Anaphase
Early Anaphase
Early Telophase, Begin cytokinesis
Late telophase, Advanced cytokinesis
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Cell ChromosomesKaryotype A picture of the
chromosomes from a human cell arranged in pairs by size
First 22 pairs are called autosomes
Last pair are the sex chromosomes
XX female or XY male
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Boy or Girl?
Y - Chromosome
X - Chromosome
The Y Chromosome Decides
Meiosis – Formation of Gametes
(Eggs and Sperm)
Spermatogenesis (formation of sperm)
Females:
Males:
Oogenesis (formation of eggs)
Two Stages: Meiosis I and Meiosis IIDuring Meiosis I – Homologs form Tetrads and crossing over occurs, all resulting cells are still diploid (2N) 46 chromosomes
During Meiosis II – Chromosomes are split and all cells become haploid (1N) 23 chromosomes
Why is this important?Entire process called reduction division
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Homologs form Tetrads Homologous chromosomes(compare to sister chromatids)
Join to form a tetrad
Called Synapsis
(compare to a centromere)
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Crossing-Over Homologous
chromosomes in a tetrad cross over each other
Pieces of chromosomes or genes are exchanged
Produces Genetic recombination in the offspring
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Crossing-over multiplies the already huge number of different gamete types
Crossing-Over
Cell Cycle and Meiosis
Lets compare Mitosis and Meiosis –
What do you know?
46 chromatids(92
chromosomes, paired after replication – held by a synapsis/centromere)
46 chromosomes each side
Mitosis: 46
chromosomesMeiosis: 23
chromosomes
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Mitosis Meiosis
Number of divisions
12
Number of daughter cells
2 4
Genetically identical?
Yes No
Chromosome #Same as parent
Half of parent
Where Somatic cells Germ cells
WhenThroughout
lifeAt sexual maturity
RoleGrowth and
repairSexual
reproduction
Comparison of Divisions