control of cell replacement
DESCRIPTION
Density-dependent inhibition Low amounts of growth factor proteins Growth Factor Secreted by cells stimulating division Enough cells, reaches GF saturation, inhibition. Control of cell replacement. Cancer - Disease of the cell cycle. Excessive division (out of control); tumor - PowerPoint PPT PresentationTRANSCRIPT
Control of cell replacement
• Density-dependent inhibition– Low amounts of
growth factor proteins
• Growth Factor– Secreted by cells
stimulating division
• Enough cells, reaches GF saturation, inhibition
Cancer - Disease of the cell cycle
• Excessive division (out of control); tumor– Benign; removed if pushing against vital organs– Malignant; disrupts normal tissue & organ function
• Metastasis; spreads to other tissues via bloodstream & lymph
• Carcinoma– Epithelial cells (e.g. skin,
intestinal lining)
• Sarcoma– Connective or supportive
tissue• (e.g. bone, cartilage,
muscles, fat, blood vessels)
• Leukemia– Blood or bone marrow;
specifically WBC’s
• Lymphoma– Originates in lymphocytes
(immune cells)
Chromosomes, sex cells, and meiosis
• Somatic cells (typical body cell) have 46 chromosomes, or 23 matched pairs
• Homologous chromosomes or homologues– Both have genes that code
for the same characteristics– Will be at the same location
or locus– e.g. if we think chromosomes
as sets of instructions or manuals, we have two versions, and loci would be chapters
Why do we have two versions?
• We inherit one from each parent
• of the 23 pairs in humans– 22 pairs are autosomes– 1 pair are sex
chromosomes• XX females• XY males
If we have two sets, than how do our gametes only have one set?
• Tetrad = homologues come together, synapsis, (each with sister chromatids)
• Crossing over = mixing or exchange of genes between homologues
• Note: no Interphase– No duplication of chromosomes
Fertilization of sperm and egg produces variety of offspring
• 3 places for variation– Tetrad formation and
crossing over• Prophase I
– Independent assortment• Depends on orientation of
chromosomes during Metaphase I & II
– Random fertilization• Preferably outside of
family
• Sites of crossing over = chiasma– Prophase I
Karyotype = inventory of chromosomes in mitotic metaphase
Karyotyping process
• centrifuge?
• Purpose / result of hypotonic solution?
• Digital arrangement of chromosomes by size & shape
• Stained and compared
Meiotic abnormalities
• Trisomy 21
Down Syndrome
Cause?
Nondisjunction
chromosome pair does not seperate
Nondisjunction can also affect sex chromosomes
• XXY: male with some female characteristics and underdeveloped sterile testes
• XO: female, typically sterile, shorter, decreased development (treated with estrogen supplements)