Cell Division mitosis and meiosis

1. Cell Divisionmitosis and meiosis

2. Limits to Cell Growth • _____ overload (information crisis) • Surface area to volume ratio (_____ increases MUCH faster than surface area.) • A cell’s s.a. cannot increase fast enough to meet the demands of the internal volume of the cell. In other words, it will not be able to bring in _____ and get rid of ______ fast enough for the cell to survive.

3. Limits to Cell Growth • _____ within a cell can only diffuse so far no matter how big the cell gets. • For example, if a cell’s volume becomes too great, CO2 will never be able to diffuse out of a cell, thereby killing the cell. • Cells need a large s.a. to take in _____ and excrete _____.

4. Limits to Cell Growth Red blood cells have a biconcave surface which increases their surface area making them more efficient at what they do best – exchange gases.

5. Prokaryotic Cell division • Binary fission • The cell simply copies its _____ info, separates that info, then splits in half – no distinct _____ occur. • Binary fission (:41) • Another one (1:03)

6. Cell division • Chromosomes • Made of _____ and _____ • Each species has its own specific number of them. (We have _____ per cell.) What is a chromosome?

7. Cell cycle – interphase • G0phase – occurs in _____ cells (like brain cells) or in cells that no longer will _____ • Most cells stop dividing after about _____ divisions. • G1 phase – cell _____ and produces new _____ and _____. • The “no turning back” phase (restriction point) • S phase – chromosomes are _____ and DNA is _____ • G2 phase – _____ and molecules needed for _____ are produced Interphase (3:45)

8. Cell cycle – interphase Ninety percent or more of the cell cycle is spent in interphase.

9. Cell cycle – prophase • Chromatin _____. • _____ migrate to opposite poles (centrosome). • _____ fibers form. • _____ _____ broken down by enzymes. • Nucleus _____. • Longest phase of mitosis

10. Cell cycle – prophase

11. Cell cycle – metaphase • _____ line up across the equatorial plate. • _____ _____ attach to kinetochores on chromatids.

12. Cell cycle – anaphase • _____ separated by spindle and pulled to opposite _____ of the cell. • Shortest phase of mitosis

13. Cell cycle – telophase • New _____ _____ form around chromosomes. • _____ uncoil and disperse within envelope. • New _____ form in each cell.

14. cytokinesis • Division of the _____ down the middle of the two new cells. • Plant cells form a _____ _____ which will become the cell _____. • Begins during anaphase once the _____ separate.

15. Review of cell cycle Mitosis video (1:30) Another video (1:00)

16. Cell lifespan • Some white blood cells, epithelial cells of small intestine – 1 day or less • Red blood cells – 120 days • Neurons, stem cells, kidney cells, eye cells, some antibodies – lifetime • The point is, all cells have a _____ which varies from one cell type to another. • What is apoptosis? (_____ _____ _____) • About 50-70 billion cells undergo apoptosis daily • Apoptosis video (2:55) • Another one (1:33)

17. Regulating the Cell Cycle • Normally, cells will stop dividing when they _____ each other. • Cells will divide rapidly at sites of _____ (skin cells at a cut). • Cyclins – • A group of _____ that regulate the _____ _____ (CA, CB, CD, CE) • Different cyclins are _____ at different times in the cell cycle. • Regulators – • A group of proteins that respond to events inside (_____ regulators) and outside (_____ regulators) the cell

18. cancer • Occurs when cells lose their ability to control their _____. (They don’t respond to _____.) • Many _____ (more than 50%) have a defect in the regulator p53 (p=protein; 53=molecular mass) • p53 was awarded Molecule of the Year in 1998. What an honor!  • p53 (1) activates DNA repair proteins; (2) halts the _____ _____ when necessary; (3) initiates _____; and (4) prevents _____ (blood vessel formation) • When the gene that controls p53 is damaged, _____ often form.

19. cancer • Differences between benign/malignant/metastatic tumors • What are carcinogens? Cancer explanation (3:50) • What are oncoviruses? • What is cancer? (1:07)

20. meiosis • Homologous chromosomes • Chromosomes that contain the same _____ (example: We get one chromo with the eye color gene on it from _____ and one from _____.) • They don’t have identical genes on them; rather, the genes control the same _____. • Meiosis video (2:58)

21. meiosis • Diploid/Haploid • Terms used to describe cells in terms of their number of _____ • Somatic cells – _____ (46) • Gametes – _____ (23) • Meiosis is a form of reduction division. It only occurs in the _____ (sperm and egg cells). • There are two distinct divisions – meiosis I and meiosis II • Both divisions are pretty much the same as _____ except prophase I.

22. meiosis • Prophase I begins with homologous _____ pairing up to form a _____ (four chromatids). • Crossing-over occurs during this phase. Exchange of _____ takes place between homologous chromosomes leading to greater _____ _____.

23. meiosis • Progression of meiosis in humans: • One cell with _____ chromatids in prophase I  two cells with _____ chromatids in prophase II  four cells with _____ chromosomes • The final result is four _____ different _____ cells.

24. meiosis Crossing Over (:43) Meiosis Video (3:03)

25. Meiosis quiz

26. REVIEW TIME! • Division of prokaryotes is called . . . • The four phases of mitosis in order . . . • Volume or surface area grows faster? • # of chromosomes in human somatic cell?

27. REVIEW TIME! • Two sista ___________ make up a chromosome. • Structures that pull apart chromosomes . . . • The “no turning back phase” . . . • # of chromosomes in human sex cell (gamete)?

28. REVIEW TIME! • New nuclei form in each daughter cell during . . . • Chromatin condenses during . . . • Chromosomes separated during . . .

29. REVIEW TIME! • Organelles that produce spindle fibers . . . • Dormant cells are in the _____ phase. • Interphase is subdivided into _______, _______, and _______.

30. REVIEW TIME! • Chromosomes line up along equatorial plate during? • Nucleus dissolves during . . . • Division of cytoplasm is called . . .