Understanding Cell Division: Mitosis and DNA Replication Explained

1. Unit 1.6 Cell Division

2. Requirements for Cell DivisionBioflix: Mitosis • Receipt of a cell signal to direct the cell to divide 2. DNA replication 3. Mitosis…DNA distribution to identical nuclei. 4. Cytokinesis

3. Which of the following are differences between cell division and mitosis? • A: Mitosis require DNA replication but cell division does not. • B: Cell division includes cytokinesis but mitosis only includes nuclear division. • C: Neither cell division nor mitosis occurs in plant cells. • D: Mitosis is part of interphase but cell division happens after interphase.

4. Uncoiled DNA in eukaryotic and prokaryotic cells.

5. Note the difference between chromosomes and chromatin. Do you understand how the different structure attests to the different functions?

6. HHMI: DNA Packaging (Movie on website-Too big to embed in the PPT)

7. After DNA replication, the DNA tightly coils into a chromosome.

8. After replication each chromosome consists of two identical DNA molecules (called chromatids) that can be distributed into two different cells Identical

9. Prior to DNA replication, there are _____ chromosomes in a pair. After DNA replication, there are ______ chromosomes in a pair. A: 2, 2 B: 2, 4 C: 1, 2 D: 1, 4

10. Identical chromatids • A: are 2 different chromosomes attached to each other. • B: are exact copies of one DNA molecule that are attached to each other. • C: arise from the ribosomes. • D: are broken down by lysosomes. • E: are chromosomes that carry different genes.

11. Cell cycle composed of interphase, mitosis and cytokinesis. Interphase has three distinct phases: • G1: cell growth and differentiation: • S: synthesis and replication of chromosomes. • G2: synthesis of molecules, other than DNA, needed for cell division. • G0: Cells that never divide, such as nerve cells

12. Which of the following occurs with DNA during interphase, mitosis and cytokinesis? A: Divides by half each time the cell divides. B: Doubles each time the cell divides. C: Doubles first and then divides by half each time the cell divides.

13. Mitosis…why bother? • Embryonic development • Growth • Tissue repair • Asexual reproduction

14. Asexual reproduction (via mitosis) and sexual reproduction (meiosis and fertilization) are different in that • A) individuals reproducing asexually transmit 100% of their genes to their progeny, whereas individuals reproducing sexually only transmit 50%. • B) asexual reproduction produces offspring that are genetically identical to the parents, whereas sexual reproduction gives rise to genetically distinct offspring. • C) asexual reproduction involves a single parent, whereas sexual reproduction involves two. • D) asexual reproduction only requires mitosis, whereas sexual reproduction always involves meiosis. • E) all of the above

15. Mitosis: equal distribution of DNA into daughter cells • 5 phases of mitosis • Prophase • Prometaphase • Metaphase • Anaphase • Telophase

16. Overview of Mitosis Meanwhile, the cytoskeleton spindle forms and the nucleus dissolves.

17. Early Prophase • Chromosomes condense • Mitotic spindle grows out of the MTOC. • Centrosomes migrate towards the poles

18. Later Prophase • Nuclear envelope disintegrates • Spindle fibers attach to the chromosomes

19. Centrosomes Mitotic spindle Microtubule

20. Nuclear envelope breaking up

21. Metaphase • The centromere-spindle complexes align in the equator of the cell.

22. Spindle microtubules 46 replicated chromosomes

23. Spindle microtubules from one pole Spindle microtubules from opposite pole

24. 46 chromosomes line up in center of cell

25. Anaphase • Chromatid separation. • Identical DNA molecules move towards opposite poles

26. Chromatid disjunction: identical DNA molecules (chromatids) are pulled apart

27. Spindle fibers from one pole attached to DNA molecule Spindle fibers from opposite pole attached to identical DNA molecule

28. Telophase • Nuclear envelope reforms. • Spindle disappears. • DNA reverts to chromatin • Nucleolus reforms.

29. 46 DNA molecules Pole Pole 46 DNA molecules

30. 46 identical chromosomes in each cell!

31. Nuclear envelopes

32. Identical daughter cells

33. Describe the events that occur in the four phases of mitosis.

34. Mitotic Spindle • Three types of microtubules; • Kinetochore: attach to each chromatid • Polar or Non-kinetochore: overlap with each other • Astral: attach the centrosome to the cell pole

35. Cytokinesis is different in animal and plant cells.

36. Starting with a fertilized egg (zygote), a series of five cell divisions (mitosis) would produce an early embryo with how many cells? • A) 4 • B) 8 • C) 16 • D) 32 • E) 64

37. Progression through the cell cycle is controlled by proteins.

38. Cyclins: family of proteins that activate a kinase that allows cell cycle to proceed.

39. Progression past G2 is controlled by interaction between cyclin-dependent kinases (CDK) and cyclins.

40. All cancer arises from one cell

43. 2 different errors in cell cycle genetic control result in same uncontrolled growth of cancer cells:Oncogenes speed up cell division.Tumor suppressor genes slow it down.

44. Accumulation of mutation

45. What is the name of the process by which cancer cells break off of tumors and spread to other parts of the body? • A: mutagenesis • B: metastasis • C: carcinogenesis • D: metamitosis • E: angiogenesis

46. Metastasis of cancer cells due to loss of density dependence/anchorage dependence.

47. The following have been diagnosed with cancer: • A: One of my parents • B: My sister or brother • C: My aunts or uncles • D: more than one of the above • E: none of the above

48. Do you… • A. Smoke? • B. Suntan during the winter? • C. Each processed meats like cold cuts or hotdogs? • D. Drink alcohol? • E: More than one of the above???

49. Some cancer statistics from ACS, 2011

50. Cancer diagnoses and deaths, 2011