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)
Each adult human consist of about 1013 (10,000,000,000,000) cells. These cells live in a gigantic "commune".
The human body contains about 200 different types of cells. Each cell has a very specialized role. Some examples:
Unicellular blood cells:
Some "tissues" in humans are populations of single cells that circulate throughout the body via the circulatory system. Examples: Erythrocytes: red blood cells transport oxygen and carbon dioxide [Image link: light micrograph]. Phagocytic white blood cells: "eat" foreign materials, infectious agents, debris [Movie link: 509K 'mov.' file, from Cells Alive! Web site. Used with permission.]
Multicellular tissue cells:
Look at any human organ, such as the liver [Image link: light micrograph]. Then look at higher magnification -- it is made of individual liver cells [Image link: light micrograph]. View an electron micrograph of one liver cell [Image link: electron micrograph]. These are often used in textbooks as examples of "typical" cells, because they lack specialized structures that make other cells so distinctively recognizable. Actually, liver cells are biochemical specialists, converting thousands of chemicals into other chemicals so that your body can either digest or excrete them. Think "detoxification center" and you'll have a good image of a liver cell. Liver cells can be damaged by excess alcohol. Look at the liver cells [Image link: light micrograph] in this image -- can you spot any changes from the healthy cells seen above?
Each cell type has a characteristic lifetime, after which it commits suicide (apoptosis). Some examples:
Neutrophils live about 1 day. [Image: light micrographs, including animation]
Each cell is totally responsible for it's own "housekeeping" duties:
maintenance and repair
acquiring food from blood or lymph
disposal of wastes into blood or lymph
synthesis and regulation of all its large biomolecules
dividing (when allowed to do so) to create new cells by the process of mitosis, and not dividing unless properly signaled (cells that divide without responding to normal signals produce CANCER).
carrying out its own specialized tasks, such as: contracting, making antibodies, firing nerve impulses, secreting digestive enzymes, etc. Examples: (1) nerve cells (communications specialists); (2) heart muscle cells (contraction specialists) [electron micrographs from Dennis Kunkel Microscopy. Used with permission].
Each cell must be able to communicate with other cells and respond appropriately to signals that regulate its activity.
Each cell must differentiate from one common ancestral cell, the fertilized egg, by a complex process of differentiation and development. Example: Developing embryo, starting from single fertilized egg. [Movie: 3.1 meg 'mov.' file, from Univ. of Penn. Health System Web site]
