Biology CH. 8

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BiologyCH. 8

• Cell Division

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CH. 8 Cell Division

• I. Cell Growth

A. Growth - increase in size and number of
cells
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B. Rate of Cell Growth

• - varies among cells

- bacteria are the fastest 20 min.
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Binary Fission - Bacteria
DNA replicated
Membrane added
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Binary Fission - Bacteria
constriction
fission
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- in humans

• - skin cell reproduce quickly
• - nerve cells reproduce very slowly

Human kidney cells dividing
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C. Controls of Cell Growth

• 1. External (Environment)
• - food, temperature, oxygen, disease,
  pollution, etc.
• 2. Internal (Heredity)
• - DNA, nucleus

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Surface Area Volume Ratio
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The Size of Cells and Their Components
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II. Cancer

• - disease in which cells have lost the ability to
  control their own growth

Cervical Cancer Cell Dividing
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A. Characteristics of Cancer Cells

• 1. Rapid cell division
• 2. Undifferentiated cells
• 3. Metastasis
• - cells don't stick together and can move
  elsewhere

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Undifferentiated Cancer Cells
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Metastasis
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B. Causes of Cancer

• - genes controlling cell division have
  mutated (changed)
• 1. Carcinogens
• - cancer causing agents
• - nicotine, asbestos, PCB's, etc.
• 2. Radiation
• - UV (sunlight), X-rays, radon, etc.
• 3. Some viruses
• 4. Hereditary factor

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MelanomaEarly Signs
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III. Cell Division

• - Mitosis
• division of the nucleus into 2 identical nuclei
• - Cytokinesis
• division of the cytoplasm to form 2 daughter
  cells

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Functions of Mitosis
Organs
Fertilized egg (zygote)
Multicell stage
Mitotic cell division Differentiation
Mitotic cell division
Tissues
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Asexual Reproduction by Mitosis
New Individuals
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Asexual Reproduction by Mitosis

• Budding
• Nucleus divides by mitosis
• Bud forms on cell

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A. Chromosomes

• - made of DNA and protein
• - stores genetic information (genes)

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Chromosome
DNA double helix
Chromatin
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1. Chromatin

• - active form of chromosomes
• - long, thin strands of DNA and protein

Chromatin
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2. Chromatid

• - one of 2 replicated halves of
  chromosomes

- Centromere point of attachment of 2
sister chromatids
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Human Chromosomes
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B. The Cell Cycle

• - 3 parts
• 1. Interphase
• 2. Mitosis
• 3. Cytokinesis

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The Cell Cycle
G0 nondividing
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C. Interphase

• - period of time between cell division
• - takes up 80 - 90 of a cell's life
• - normal cell activity and growth

Nucleus
Nuclear Membrane
Chromatin
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C. Interphase

• - period of time between cell division
• - takes up 80 - 90 of a cell's life
• - normal cell activity and growth

1. Cell growth 2. DNA replication 3. Synthesis
of organelles and centrioles
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D. Mitosis

• - 4 stages (P, M, A, T)

Prophase
Anaphase
Metaphase
Telophase
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1. Prophase

• - first and longest stage
• a. Chromatin condenses to form chromosomes
• b. Centrioles move to opposite ends of
  the cell - animal cells only

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• c. Spindle fibers form
• - protein fibers that aid in movement of
  chromosomes
• d. Nuclear membrane and nucleolus disappear

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2. Metaphase

• - second and shortest stage
• - chromosomes line up along the middle of the
  cell

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3. Anaphase

• - centromeres split and chromosomes move
  apart to opposite sides of the cell

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4. Telophase

• - last stage
• - "reverse" of prophase
• a. Chromosomes revert to chromatin
• b. Spindle fibers disappear
• c. Nuclear membrane and nucleolus reform

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E. Cytokinesis

• 1. Animal Cells
• - Cell membrane pinches in forming 2
  daughter cells

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2. Plant Cells

• - Cell plate forms between 2 daughter cells

Cell plate
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Which stage of mitosis?
Early Anaphase
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Which stage of mitosis?
Prophase
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Which stage of mitosis?
Metaphase
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Which stage of mitosis?
Telophase
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Which stages of mitosis?
Prophase
Interphase
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Which stage of mitosis?
Metaphase
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Which stage of mitosis?
Prophase
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Which stage of mitosis?
Telophase
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Which stage of mitosis?
Anaphase
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Which stage of mitosis?
Interphase
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The End