Cancer, Haploid/Diploid Cells and Somatic/Gametic Cells Biology K. Beris

Normal and Abnormal Cell Growth Enzymes control cell division Cancer: Cell death or uncontrolled cell growth (or uncontrolled dividing of cells) Caused by a lack of or too much of enzymes Caused by defective genes Thought to be caused by changes in genes controlling mitosis

Normal and Abnormal Cell Growth, cont. Contact inhibition Cells stop dividing when they come in contact with each other Abnormal cells continue to grow They form masses of tissues called tumors Cancer cells mass of tissue  tumor If malignant, the cancer can spread

Normal and Abnormal Cell Growth, cont. Causes of cancer: Anything that damages the genes that control the cell cycle Cigarette smoke Air and water pollution UV radiation

Differences between Diploid and Haploid Cells Each species has a certain number of chromosomes Example: Humans have 46 chromosomes Homologous chromosomes Pairs of chromosomes with similar information Example: humans have 23 pairs of homologous chromosomes (23 from each parent)

Differences between Somatic and Gametic Cells Somatic Cells Body cells Contain two of each chromosome Diploid number Example: human somatic cells have 46 chromosomes (the diploid #) Gametic Cells: Sex (reproductive) cells Contain only one of each chromosome Haploid number Example: human gametes only have 23 chromosomes (haploid #) Male gamete—sperm Female gamete—egg or ovum