2 2 Cell Cycle Cell cycle- The sequence of stages through which a cell passes between one cell...
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Transcript of 2 2 Cell Cycle Cell cycle- The sequence of stages through which a cell passes between one cell...
MitosisBody Cell Reproduction
2 2
Cell Cycle
Cell cycle- The sequence of stages through which a cell passes between one cell division and the next. (The cycle begin growth and division. )
Cell Cycle The cell spends most of its time in
interphase.
Stage 1- G1- cell grows, organelles may begin to duplicate, cytoplasm increases and protein synthesis occurs
Stage 2- S- DNA replicates
Stage 3- G2-cell continues to grow, organelles double, and microtubules synthesize
Mitosis Mitosis is a type of cell division
that generates two identical daughter cells.
Mitosis occurs in body cells.
Body cells are called somatic cells.
Mitosis Mitosis is a part of the cell cycle. It has 4
phases. (PMAT)
Human cells have 46 chromosomes or 23 pairs. This is called a diploid number. (2N)
Mitosis requires only one parent -asexual reproduction.
How do little elephants grow up to be BIG elephants?
Why do animals shed their skin?
Three reasons why cells reproduce by mitosis:
1. Growth 2. Repair 3. ReplacementSkin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.
Cell that reproduce by asexual reproduction reproduce constantly.
Animated Mitosis Cyclehttp://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
Interphase occurs before mitosis begins
• Chromosomes are copied (# doubles)• Chromosomes appear as threadlike coils
(chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase
CELL MEMBRANENucleus
Cytoplasm
Interphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Prophase 1st step in Mitosis
• Mitosis begins (cell begins to divide)• Centrioles (or poles) appear and begin to
move to opposite ends of the cell. • Spindle fibers form between the poles.
CentriolesSister chromatids
Spindle fibers
Prophase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Spindle fibers
Metaphase 2nd step in Mitosis
• Chromatids (or pairs of chromosomes) attach to the spindle fibers.
Centrioles
Spindle fibers
Metaphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Anaphase 3rd step in Mitosis
• Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.
Centrioles
Spindle fibers
Anaphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Telophase 4th step in Mitosis
• Two new nuclei form. • Chromosomes appear as chromatin
(threads rather than rods).• Mitosis ends.
NucleiNuclei
Chromatin
Telophase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Cytokinesisoccurs after mitosis
• Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- ReviewInterphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
24
Cell Cycle
Questions Sec 1 1. What is a gene? 2. What are chromosomes? 3. Describe a prokaryotic chromosome. 4. Describe a eukaryotic chromosome. 5. What is chromatin? 6. What is a chromatid? 7. What is a centromere?
Questions Sec. 2 and 3
1. Define Cell Cycle.1. 2. What is mitosis? 3. What is cytokinesis? 4. What is a spindle
fiber?
Questions Sec. 2 and 3
1. Define Cell Cycle.1. 2. What is mitosis? 3. What is cytokinesis? 4. What is a spindle
fiber?
CHROM…words
Chromatin – uncoiled DNA + proteins (threads)
Chromosome – coiled DNA + proteins (Looks like an X)
Chromatid – only half of a chromosome
Sister chromatids – Two chromatids joined together, by a centromere, to form a chromosome
Mitosis Animation
http://www.cellsalive.com/mitosis.htm