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Explore the intricate process of cell division, mitosis, and the implications of abnormal cell growth leading to cancer. Learn about the significance of chromosomes, genetic variation, and the role of checkpoints in the cell cycle. Discover common types of cancer, treatment options, and preventive measures for a healthier lifestyle.
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Mitosis- Chapter 6 Sections 1-3
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.
Why do cells divide? • Repair • Growth & development • Make gametes (sex-cells; sperm or egg)
Asexual Reproduction • Reproduction by • Binary Fission • Fragmentation • Vegetative Propagation • Genetically identical offspring • Don’t need partner to reproduce
Sexual Reproduction • Reproduction requires gametes • Genetically different offspring
Sexual Reproduction- Simple version • Daddy’s sperm meet Mommy’s 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
Prokaryotes vs Eukaryotes • Prokaryotes use asexual reproduction • Eukaryotes may use asexual OR sexual reproduction • Prokaryotes reproduce more quickly • Eukaryotes reproduce more slowly
Focus on Eukaryotes (us) • Gene- part of DNA that codes for particular trait • Chromosome- made of coiled DNA and protein
More Important Terms • Centromere- center point where two chromatids are attached • Chromatid- half of a chromosome Chromosome
Eukaryote Cell Division http://www.cellsalive.com/cell_cycle.htm
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
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
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!
Basic Steps of Mitosis: “PMAT” • P- Prophase • M- Metaphase • A- Anaphase • T- Telophase
Prophase • Nuclear membrane dissolves • Chromosomes become visible
Metaphase • Chromosomes align on the equator • Spindle fibers form and attach to centromere
Anaphase • Centromeres break • Chromatids move toward the poles as spindle fibers shorten
Telophase • Nuclear envelope forms • Cleavage furrow in animals • Cell plate in plants • Daughter cells form when Cytokinesis (cell splits into two) occurs
When Mitosis goes bad • Cell Cycle checkpoints don’t work properly • Cell can divide when it shouldn’t • Cell can mutate • A benign (harmless) tumor can form • Cancer may develop
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
Lymph vessels Tumor Glandular tissue Metastasis A tumor grows from a single cancer cell. Cancer cells invade neighboring tissue. Cancer cells spread through lymph and blood vessels to other parts of the body Figure 8.9
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
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
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