Cell Division

1. Cell Division Mitosis vs. Meiosis Ch. 10 & Ch. 11-4

2. True or False • Mitosis occurs in sex cells and meiosis occurs in body cells. • Centrioles are involved in cell division in both plants and animals. • Each human body cell has 23 chromosomes. • Chromosomes are tightly coiled DNA. • Each chromosome has 2 sister chromatids.

3. Why do cells divide? 1) ______________: • increase number of cells by cell division • replace worn out or damaged cells; occurs via _________ 2) ______________: • _________ reproduction = production of offspring from one parent (in ________); ____________ • _________ reproduction = formation of a new individual from union of 2 sex cells (fertilization of sperm and egg); occurs via ___________

4. Cell Cycle • the sequence of cell growth and division that occurs in a cell (Interphase) ___ -> ___ -> ___ -> Mitosis/meiosis ____ = rapid growth ____ = DNA synthesis/replication ____ = centrioles replicate

5. _________ is DNA wrapped around proteins called _________. A _________ has two sister _________ held together by a ___________. Chromtain, Chromatid, Chromsome

7. 4 Phases of Mitosis • _________ - Chromosomes appear; nuclear membrane disappears; centrioles start migrating to opposite ends; spindle fibers start forming • _________ - Chromosomes line up on spindle fibers along the equator of the cell. • _________ - Centromeres split apart and sister chromatids separate. • _________ - Chromatids reach the opposite ends; chromosomes unwind; spindle breaks down; nuclear membrane reappears; _________ (splitting of cytoplasm);

10. 4 phases of mitosis

11. Phases of Mitosis Analogy Interphase (G1, S, G2) __________________ • Prophase (_________) • Metaphase (___________________) • Anaphase (_______________________) • Telophase (__________________)

12. Difference between animal and plant cell division • Plant cell forms ______ (new cell wall forms on each side of cell plate) during Telophase whereas animal cell cytoplasm pinches in along the equator. • Plant cells DO NOT have _________.

14. Mitosis ________ reproduction _______cells (body cells) ___ division __ daughter cells formed Daughter cells are identical to parent cells Chromosome # is ___________(_______) No pairing of _________ chromosome No _______________. Meiosis ________ reproduction __________ cells (eggs & sperms = _________) ____ divisions __ daughter cells formed Daughter cells are NOT identical to parent cells Chromosome # is _____ (________) Pairing of ___________ chromosome __________ btwn _________ chromosome may occur Mitosis vs. Meiosis

15. # of Chromosomes • Humans have ____ chromosomes in a body cell. ________ • Humans have ____ chromosomes in reproductive cells such as sperm or egg. ________

16. Fertilization ________ sperm (___) + egg (___) _______ (a fertilized egg ) (___) -> embryo

17. Meiosis

18. True or False • Mitosis occurs in sex cells and meiosis occurs in body cells. • Centrioles are involved in cell division in both plants and animals. • Each human body cell has 23 chromosomes. • Chromosomes are tightly coiled DNA. • Each chromosome has 2 sister chromatids.

19. Homologous chromosomes • Each pair of homologous chromosomes has genes for the ________ ( such as hair color/eye color) arranged in the _________. It may not be exactly identical though b/c of different __________ (forms of genes). • Homologous chromosomes may cross-over during the __________ of ________.

20. Crossing Over(during Prophase I)

21. Meiosis I Homologous chromosomes pair up and cross over during ___________. ________________split. ___ lines Chromosomes # is ________. Meiosis II Homologous chromosomes do not line up. _______________ split. ___ line Similar to _______ Chromosome # stays as ________. How is Meiosis I different from Meiosis II?

24. True or False • Homolgous chromosomes line up during the metaphase of mitosis. • Crossing over occurs between 2 sister chromatids. • In meiosis II, sister chromatids split, not homologous chromosomes. • Mitosis produces haploid cells and meiosis produces diploid cells. • Cytokinesis occurs during the anaphase of mitosis and meiosis.

25. What is Cancer? • ____________ cell division caused by damage to ______ regulating the cell division cycle. • Types of Cancer • _______ - a sedentary mass of cancerous cells • ________ - a moving mass of cancerous cells metastasis

26. Causes of Cancer • Carcinogenic chemicals, _______, ______ • Mechanism – ___________. • ________ agents cause mutations in genes that encode for proteins that regulate cell division and growth; cell growth is no longer under control. • Picture of lung cancer

27. Cancer Statistics • Of the children born in 1999, one-third will contract cancer at some time during their lives; one-fourth of the male children and one-third of the female children will someday die of cancer. • Most of us have had family or friends affected by the disease. • In 2002, an estimated 550,000 Americans died of cancer.

28. Non-disnjunction • chromosomes fail to separate during _________ (an error in ________) • Leads to genetic disorders such as ________, ________ and ________.

29. Disorders caused by non-disjunction Ex: _________- one too few chromosomes -Turner Syndrome (XO) _________- one too many chromosomes -___________ (trisomy 21) -________________ (XXY)