1. Cell Reproduction
Chapter 8

2. Henrietta Lacks
cervical cancer
HeLa Cells

3. Cell Division Mitosis Meiosis How body cells divide
Makes exact copy – clone - of parent cell
Identical daughter cells
Meiosis
Makes sex cells – eggs and sperm
Contain only one chromosome of a pair
Half the normal number of chromosomes

4. Prokaryotic cell division
No nucleus or organelles, and only one circular chromosome
Process is called binary fission
Not mitosis since there is no nucleus to divide

6. Eukaryotic cell division
More complicated
More DNA
Chromosomes come in pairs:
homologous chromosomes

8. Cell cycle All the processes from one division to the next:
Interphase – “resting stage”
Mitosis – nuclear division
Cytokinesis – division of the cytoplasm

10. Interphase Cell is busy doing its job – just not dividing Three parts:
Nerve cells spend most of life in interphase
Cancer cells spend little time in interphase
Three parts:
G1 or Gap 1 or growth phase
S phase : Synthesis of DNA ; cell is committed to division
G2 or Gap 2

11. Mitosis Refers specifically to division of the nucleus Four phases:
Prophase
Metaphase
Anaphase
Telophase
PMAT

12. Prophase Chromosomes wind up or condenses
2 meters / cell
Linked by centromere
Sister chromatids
Nucleoli disappear; mitotic spindle forms from the centrioles

19. Prometaphase or late prophase
Transition phase – to cell it is all part of one process
Nuclear membrane disappears
Chromatids attach to fibers of mitotic spindle by means of specialized structure called a kinetochore

23. Metaphase
Chromosomes line up in the center of the cell at the metaphase plate – a disc
Remain this way for about an hour

26. Anaphase Centromere splits
Microtubles of mitotic spindle pull members of each pair of duplicate chromosomes to opposite sides of the cell.

30. Telophase Mitotic spindle disappears Nuclear membranes form
Chromosomes unwind

33. Cytokinesis Division of the cytoplasm Accompanies mitosis
Begins in anaphase and finishes after telophase
Animal cells form a contractile ring using actin – one of the proteins found in muscles.
Indentation is called the cleavage furrow
Pinches the cells apart

37. Plant cells
Mitosis occurs in plants as in animal cells, but cytokinesis is different because of the plant cell wall.
A disc of new membrane called the cell plate forms between the two cells during telophase and expands until it reaches the edges of the cell membrane.
The new cells then make cellulose fibers to form new cell walls.

39. Control of cell division
Cell senescence – cells reproduce only a certain number of times and then stop.
May be due to telomeres –repeating series of bases at the end of chromosomes that decrease with each division
Telomerase
Apoptosis – programmed cell death –”suicide genes”

41. Contact inhibition
Cells divide until they establish contact with other cells on all sides.

43. Other factors Cell size hormones Growth factors Cyclins Genes:
Oncogenes – want these turned off
Oncology – the study of cancer
Tumor suppressor genes – want these turned on

44. Tumors - neoplasms Cells have lost control over cell division
Benign tumors grow only in one area
Cancers invade local tissues (look like a crab) and can metastasize or spread to other areas of the body through the vascular or lymphatic systems