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Unformatted text preview: BIO115
Cellular Reproduction Dr. Jessica Pamment Overview Overview
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Relevance of cellular reproduction The cell cycle Mitosis Meiosis Functions of Cell Division
• In unicellular organisms a single division produces two new organisms • In multicellular organisms many rounds of division are required to make a new individual • Division required throughout life of multicellular organisms to replace old/damaged cells The Functions of Cell Division The
100 µm 200 µm 20 µm (a) Reproduction (b) Growth and development (c) Tissue renewal Asexual Reproduction by Mitosis Asexual Reproduction by Mitosis Asexual reproduction http://video.search.yahoo.com/search/video;_ylt=A0PDoS71H09NIx0AG3OJzbkF?ei=UTF8&p=regeneration %20of%20sea%20star%20arms&fr2=tabimg&fr=yfpt701 Asexual Reproduction Asexual Reproduction
• Results in clones (genetically identical individuals) • Mitosis is underlying mechanism • Takes place in prokaryotes, unicellular eukaryotes and some multicellular organisms Asexual Reproduction in hydra 0.5 mm Parent Bud (a) Hydra Eukaryotic Chromosomes
• Humans have approx. 21,000 genes/cell • Genes are located on chromosomes • Humans contain 46 chromosomes in each cell (except gametes, these contain 23) Eukaryotic Chromosomes Eukaryotic 20 µm The amazing feats of DNA packaging! • In a mammalian cell…. • The DNA, if stretched out, is 2 m in length • The nucleus is approx. 6 µ m • This means the DNA is 333, 333 times longer than the nucleus is in diameter!!! DNA Packaging DNA Packaging in a eukaryotic chromosome
Level 1 Level 2 Level 3 Levels of DNA Packaging • DNA is wrapped around proteins to make chromatin • Chromatin is coiled further into chromosomes Chromosome Chromosome Duplication and Distribution The Cell Cycle The Cell Cycle
• Is the life of a cell from when it is just formed until it undergoes its own division • Duration varies between organisms Phases of the Cell Cycle Phases of the Cell Cycle
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Mitotic phase: Mitosis (division of nucleus) Cytokinesis (division of cytoplasm) Interphase: accounts for 90% cycle Cell grows & chromosomes duplicate The The Eukaryotic Cell Cycle Chromosome Changes During Cell Division Chromosome Mitosis in Plant Cell Mitosis Nucleus Chromatin condensing Chromosomes Cell plate 10 µm 1 Prophase 2 Late prophase 3 Metaphase 4 Anaphase 5 Telophase Mitosis in an Animal Cell Mitosis G2 of Interphase Prophase Prophase Metaphase Anaphase Telophase and Cytokinesis The The Eukaryotic Cell Cycle Control of Eukaryotic Cell Cycle Control of Eukaryotic Cell Cycle G1 checkpoint G1 Control system S M G2 M checkpoint G2 checkpoint Cancer cells Cancer cells • Single cell undergoes transformation
transformed cell, it can proliferate Cancer Development Cancer Development • If body’s immune system doesn’t destroy • Tumor is mass of abnormal cells • Benign tumor cells remain in original site, is not aggressive • Malignant tumor cells become invasive and patient has cancer The Growth and Metastasis of a Malignant Breast Tumor Tumor Cancer Treatments Cancer Treatments
• Surgery • Radiation therapy for localized tumors • Chemotherapy for metastatic tumors uses drugs to destroy cancer cells Half of all Americans will develop cancer during their lifetime.
http://seer.cancer.gov/statfacts/html/all.html#risk Cancer Prevention and Survival Cancer Prevention and Survival
• Cancer can strike everyone • Some people are genetically predisposed • Lifestyle can reduce your chances • Regular checkups for prevention Summary Summary
• Cell division by mitosis results in two genetically identical daughter cells • Mitosis used by unicellular organisms to reproduce and by multicellular organisms to grow and repair tissues and mitotic phases • The cell cycle consists of the interphase G1 Cytokinesis Mitosis MITOTIC (M) PHASE G2 S Prophase Telophase and Cytokinesis Anaphase Metaphase Late prophase Summary Summary
• The eukaryotic cell cycle is regulated by a molecular control system • Checkpoints are found at 3 different phases • Loss of cell cycle controls results in cancer cells The cell cycle is linked to cancer because cancer always entails: a.Too much time spent in S phase b.A slowdown in mitosis c.Unrestrained cell division d.A misalignment of chromosomes e.Not enough time spent in M phase Cell division has two separable components: Mitosis is the movement of a cell’s .……into opposite parts of the cell, while cytokinesis is the physical separation of one cell into two……… In mitosis, the apportioning of DNA comes about through the separation of ..…., each of which then becomes a fully functional……. in one of the newly formed daughter cells. A gene can be described as: a.A protein that contains enough information to carry out a task b. A hormone that prompts some action inside a cell c. A series of DNA bases that transfer energy within a cell d. A series of DNA bases that contain information for production of a protein e. A protein that delivers information to a ribosome Biology and Society
• The recent availability of genetic tests for susceptibility to some types of cancer has led some patients to take extreme measures, such as having a mastectomy when there is a risk, though not a certainty, of developing breast cancer. Issues to consider
• Is the doctor responsible for educating the patient about all of the preventive and diagnostic measures? • Should the patient’s wishes always be followed, regardless of the outcome? • How accurate would the testing have to be for you to decide to go ahead with a mastectomy? • HeLa cells are an immortal cell line derived from Henrietta Lacks, who died from cervical cancer in 1951. • Her doctor used her cancer cells without her permission and now this cell line is one of the most widely used cell lines in biology research. • In 1990 the Supreme Court of California ruled a •
person’s discarded cells/tissues were not their property and could be commercialized. Thoughts???? ...
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