Mitosis- Chapter 6

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Mitosis- Chapter 6

• Sections 1-3

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Objectives-

• Identify four examples of cell division in
  eukaryotes and one example in prokaryotes.
• Differentiate between a gene, a DNA molecule, a
  chromosome, and a chromatid.
• Compare haploid and diploid cells.
• Differentiate between homologous chromosomes,
  autosomes, and sex chromosomes.
• Predict how changes in chromosome number or
  structure can affect development.

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Why do cells divide?

• Repair
• Growth development
• Make gametes (sex-cells sperm or egg)

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Asexual Reproduction

• Reproduction by
• Binary Fission
• Fragmentation
• Vegetative Propagation
• Genetically identical offspring
• Dont need partner to reproduce

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Binary Fission
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Fragmentation
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Sexual Reproduction

• Reproduction requires gametes
• Genetically different offspring

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Sexual Reproduction- Simple version

• Daddys sperm meet Mommys egg
• This sperm eats a hole for itself into the egg
  to get its DNA in
• This fertilized cell is called a zygote
• This zygote divides and grows into a baby by
  Mitosis

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Prokaryotes vs Eukaryotes

• Prokaryotes use asexual reproduction
• Eukaryotes may use asexual OR sexual reproduction
• Prokaryotes reproduce more quickly
• Eukaryotes reproduce more slowly

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Prokaryotes vs Eukaryotes
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Focus on Eukaryotes (us)

• Gene- part of DNA that codes for particular
  trait
• Chromosome- made of coiled DNA and protein

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More Important Terms

• Centromere- center point where two chromatids are
  attached
• Chromatid- half of a chromosome

Chromosome
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Eukaryote Cell Division
http//www.cellsalive.com/cell_cycle.htm
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Cell Cycle
S phase (DNA synthesis chromosome duplication)

• Consists of
• Interphase
• Mitosis

Interphase (90 of time)
G1
G2
Mitotic phase (M) (10 of time)
Mitosis
Cytokinesis
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Interphase

• Cell spends 90 of its time here
• G1- 1st growth phase
• S- synthesis of DNA
• G2- 2nd growth phase
• There are checkpoints throughout the cell cycle

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Mitosis- (growth/repair)

• Begins with 1 diploid cell, ends with 2 diploid
  cells
• Diploid twice the number of chromosomes (2N)
• One chromosome set comes from mom, the other from
  dad
• All of our body cells are diploid (except for
  sperm and egg)

Remember produces 2 genetically identical cells!
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Basic Steps of Mitosis

• PMAT
• P- Prophase
• M- Metaphase
• A- Anaphase
• T- Telophase

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Prophase

• Nuclear membrane dissolves
• Chromosomes become visible

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Metaphase

• Chromosomes align on the equator
• Spindle fibers form and attach to centromere

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Anaphase

• Centromeres break
• Chromatids move toward the poles as spindle
  fibers shorten

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Telophase

• Nuclear envelope forms
• Cleavage furrow in animals
• Cell plate in plants
• Daughter cells form when Cytokinesis (cell splits
  into two) occurs

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Cleavage Furrow
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Cell Plate
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When Mitosis goes bad

• Cell Cycle checkpoints dont work properly
• Cell can divide when it shouldnt
• Cell can mutate
• A benign (harmless) tumor can form
• Cancer may develop

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Cell Cycle CheckPoints
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What is Cancer?

• Named for organ or tissue where its found
• Cells that divide out of control due to a
  mutation in the DNA
• These out of control cells can destroy/invade
  normal cells and tissues
• Cancer can spread from a malignant (harmful)
  tumor
• Metastasis is cancer cells that have spread

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Figure 12-17x1 Breast cancer cell
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Common Types of Cancer
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Cancer Treatment

• Radiation can be used for skin cancer
• Chemotherapy involves drugs that stop Mitosis
  throughout the body
• Chemotherapy drugs not only try to kill cancer
  cells but it makes wounds slower to heal, hair to
  be lost, immune system to be weakened

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Cancer Caution Signs

• Change in potty habits
• A sore that does not heal
• Unusual bleeding or discharge
• Thickening of tissue or new lump
• Indigestion
• Obvious changes to moles or warts
• Nagging cough that lasts for a month or more

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Cancer Prevention-what YOU can do

• Not smoking
• Limiting time in the sun
• Eating high-fiber, low-fat diet
• Visit Doctor regularly
• Perform regular self-examinations