IAS OUR DREAM: Cell Division

events involving meiosis, showing chromosomal ...

I Cancer - Practical Applications and Cellular Reproduction

 A) Definition of Cancer
  1) neoplasm of proliferating cells, cell division out of control, cells
   produced are useless, compete with healthy cells for nutrients
   and oxygen
  2) Benign versus malignant
   a) benign is a sedentary mass of cancerous cells
   b) malignant is a moving mass of cancerous cells
    metastasis
  3) Basic types
   a) carcinoma - arises from body's outer coverings and inner linings
   b) sarcoma - arises from body's supporting structures
   c) lymphoma - arises from lymph system
   d) leukemia - arises from blood marrow in bone, spleen
 B) Causes of Cancer
  1) Carcinogenic chemicals
  2) UV Light
  3) Viruses
  4) Mechanism - mutations and oncogenes
   a) cell growth is no longer under control, mutagenic agents
    cause mutations in proto-oncogenes (genes that encode for
    proteins that stimulate cell division and growth), these genes become
    oncogenes that cause cancer

Problem	Effect
Mutation in proto-oncogene	creates hyperactive protein
Multiple copies of a gene	produces excess amount of protein
Movement of gene locus	no longer under control from original locus, produces excess amount of protein

  5) Mechanism - mutations to tumor-suppressing genes
   a) mutation in a gene that inhibits cell division, produces
    a faulty protein that can not stop cell division
 C) Consequences
  1) alteration of DNA
  2) Cancerous growth - tumor or polyp
 D) Diagnosis
  1) Radiology (x-rays and dyes)
  2) Ultrasound imaging
  3) Endoscopy - fiber optics (example - colonoscopy, inside the esophagus)
  4) Biopsy
  5) Monitoring chemical levels in the blood (blood testing)
  6) Mammogram for breast cancer
   
 E) Treatments
  1) Surgery (physical removal)
  2) Radiation Therapy (Radiation - high energy particle beams)
  3) Chemotherapy (cytotoxic drugs - chemotherapeutic agents)
   disrupts DNA synthesis or  mitosis, affects normal cells also
   some bad side-effects
  4) Hormone therapy - used for cancers associated with sex hormones
   tamoxifen suppresses estrogen used to treat breast cancer
   anti-androgens used to treat prostate cancer (reduce androgen levels)
  5) Boosting the immune system (stimulate the production of cells that
   recognize healthy versus unhealthy or cancerous cells)
  6) Diet
  7) Monoclonal antibodies - silver bullets, respond to protein on cancer cell
   surface and deliver cytotoxic drug
 F) Types of Cancers - some examples of virus related cancers
  1) Leukemia - associated with bone marrow cancer
  2) HIV - associated with cancers in blood vessels (Kaposi's Sarcoma)
  3) Hepatitis B, C virus - associated with liver cancer
  4) Papilloma virus - causes genital warts and benign cancers, associated with cervical cancer
 G) Types of Cancers - some examples of Carcinogen related cancers
  1) Lung cancer - tobacco
  2) oral cancer - chewing tobacco
  3) Bladder and rectal cancer
 H) Types of Cancers - some examples of Light related Cancers
  1) UV light - lesions and melanomas
 I) Other cancers
  Breast cancer in females and males
  Prostate cancer in males
 J) Summary - types and incidence

II Cellular Reproduction

 A) Two types of cell division
  1) Mitosis and Fission- results in exact duplication of parent cell (2N to 2N)
    Binary Fission - special cell division in bacteria
  2) Meiosis - results in production of gametes (2N to 1N)
 B) Mitosis
  1) Functions
   a) cell reproduction
   b) replacement of cells
   c) healing
   d) growth
   e) regeneration (in some organisms)
  2) Phases
   a) Cell cycle (cell division, G1, S - duplication phase, G2)
   b) S phase - duplication of chromosomes, sister
    chromatids bound by centromere
   c) Prophase (appearance of chromosomes)
   d) Metaphase (lining up along the equator)
   e) Anaphase (splitting of the chromosomes)
   f) Telophase (segregation, cell plate appears in plants)
   g) Differs between plants and animals
    animals (see whitefish blastula above)
    plants (onion root tip you will observe in lab)
   h) Cytokinesis (splitting of cytoplasm) not part of mitosis
    in animals
 C) Meiosis - characteristics
  1) Function - sexual reproduction
   a) diploid (2N) adult produce gametes (sperm, eggs = haploid - 1N)
  2) two cell divisions in order to produce haploid gametes
  3) restricted to gonads
 D) Meiosis - mechanics of the phases
  1) Meiosis I: prophase I, metaphase I, anaphase I, telophase I
   a) metaphase I - homologous pairs line up across the equator
    from each other
   b) anaphase I - homologous pairs are split (reduction of
    chromosomes = 2N - 1N condition)
  2) Meiosis II: prophase II, metaphase II, anaphase II, telophase II
   a) metaphase II - chromosomes line up along the equator
    like they were going through a mitotic division
   b) anaphase II - chromatids are split by breaking the
    centromere (in animal cells)
 E) From Meiosis to gamete production
  1) Making sperm

Cell Type	Cell Division	Product
Spermatagonium (2N)	Undergoes Mitosis	Primary Spermatocyte (2N)
Primary Spermatocyte (2N)	Undergoes Meiosis I	2 Secondary Spermatocytes (1N)
Secondary Spermatocyte (1N)	Undergoes Meiosis II	Spermatid (1N)
Spermatid (1N)	Maturation - no cell division	Sperm cell (1N)


  2) Making eggs

Cell Type	Cell Division	Product
Oogonium (2N)	development - no cell division	Primary Oocyte (2N)
Primary Oocyte (2N)	Undergoes Meiosis I	Secondary Oocyte (1N) and First Polar Body (1N)
Secondary Oocyte (1N)	Undergoes Meiosis II (stimulated by fertilization from sperm)	Ovum (1N) and Second Polar Body (1N)


   
 F) Maintaining Genetic Variation
  1) Genetic Recombination
  2) Crossing Over

Saturday, October 3, 2009

Cell Division