Cells, chromosome, & Cell Division

• Eukaryotic cell with organelles

• Cell membrane• Nucleus• Mitochondria• Lysosomes: Tay-

Sachs Disorder

Cell membrane

• Lipid bilayer• Proteins• Cholesterol• Fluid• Cystic fibrosis:

membrane protein, transport of Cl-

Mitochondria

• Cell Respiration• DNA• RNA• Ribosomes• Genetic disorders• Maternal inheritance

Nucleus

• Chromosomes• Chromatin: DNA and

proteins• Heterochromatin• Euchromatin• Haploid: one set• Diploid: two sets• Homologous

chromosomes

Cell Cycle

• Production of new cells for repair, growth

• Interphase (3 stages)• Mitosis = separation

of chromosomes• Go• Environmental factors• Hormonal factors

Mitosis

Regulation• CDC mutations: 3 checkpoints involved with cyclins• G1/S: cell size, DNA damage, cannot proceed to S• G2/M: Repilication or damage• M: formation of spindle fiber system, not attached

properly• Tumor suppressor genes: P53 program cell death

Meiosis• Only in diploid cells• Diploid to haploid• Replicate DNA once• 2 cell divisions• Production 4 haploid cells• Increase genetic

variability• Recombination• Independent assortment

of homologues• Non-disjunction

Meiosis in humans

Comparison: Mitosis and Meiosis

Genetic Variation

Cell Division Summary

• Mitosis is essential for growth and replacement

• Regulation of cell cycle is important • Cancer is cell cycle regulation with loss of

control• Meiosis produces gametes and genetic

variation• Non-disjunction causes abnormal gametes

and chromosomal inbalance