1. Cell Growth and Division
Chapter 10(M)

2. Limits to Cell Size Cells grow and increase in size
Upper limit to the size of a single cell
If cells keep growing
More demands are placed on the DNA
Cells becomes less efficient in moving nutrients and wastes
Cells divide before it becomes too large

3. Cell Size
As a cell increases in size its volume increases faster than its surface area.
Smaller objects have a greater ratio of surface area to volume.

4. Purpose of Cell Division
Cell division  essential for life
Repair replacement of lost or damaged cells
Skin cells are constantly being replaced
Growth cells divide and increase in size, so that organism can grow
To maintain a favorable Surface area to volume ratio
Infant Baby Child Adult

5. Cell Division and Reproduction
Asexual Reproduction
Sexual Reproduction

6. Asexual Reproduction Production of offspring from a single parent
Offspring is identical to parent
Ex bacteria, yeast, unicellular organisms & some multicellular organisms

7. Binary Fission Bacteria

8. Budding Yeast

9. Sexual Reproduction Two parents are involved
Genetic material from each parent combines
Offspring is different from parent

10. The Process of Cell Division
Genetic material - packaged as DNA is distributed to two daughter cells
mitotic chromosome
DNA
chromatin

11. Chromosomes and Cell Division
Chromatin fibers of DNA and protein
Chromosomes Chromatin fibers condense and become visible compact structures
Sister Chromatids before the cell divides the DNA duplicates and forms identical copies

12. Prokaryotes and Eukaryotes
Prokaryotes, the genome is often a single long DNA molecule
Eukaryotes, the genome consists of several DNA molecules
DNA is passed from one generation to the next

13. The Cell Cycle
An orderly sequence of events that extends from the birth of a cell till the time it divides itself
All Eukaryotic cells undergo this cycle
Cycle is divided into
Interphase
Mitotic Phase

14. The Cell Cycle

15. Interphase 90% of the Cell Cycle
G1(gap)phase: cell spends most of its functional life.
Gap bet. DNA syn & cell div
Cell grows, protein & organelles synthesized

16. Interphase 90% of the Cell Cycle
G1(gap)phase: cell spends most of its functional life.
Gap bet. DNA syn & cell div
Cell grows, protein & organelles synthesized

17. Interphase contd. S-Phase the DNA synthesis phase.
DNA molecules are copied or replicated, single stranded DNA in G1 phase to double stranded DNA in G2.
G2 Phase completion of DNA syn. & onset of cell division

18. Mitotic Phase
Division of the nucleus plus cytokinesis,  produces two identical daughter cells
Interphase is not part of mitosis, it encompasses stages G1, S, and G2 of the cell cycle.

19. Interphase Chromatin not visible DNA replicated
New organelles are formed
Cell grows by producing proteins and cytoplasmic organelles
Prepares for cell division.

20. Mitosis Division of the Nucleus Stages Prophase Metaphase Anaphase
Telophase

21. Prophase
Chromosomes condensed and visible with sister chromatids joined together
The nucleoli disappear
Centrioles at opposite poles of cell
The mitotic spindle begins to form
Phase ends with the breakdown of the nuclear membrane

22. Metaphase The second stage
Chromosomes gather in the a plate across the middle of the cell
Mitotic spindle is fully formed
All chromosomes are attached to the spindle microtubules

23. Anaphase The third stage of mitosis
The sister chromatids suddenly separate from their partners.
Each chromatid  daughter chromosomes move toward the poles
Microtubules shorten, bringing the chromosomes closer to the poles.

24. Telophase Cytokinesis follows The final stage of mitosis
The chromosomes reach the poles of the spindle.
The reverse of prophase spindle disappears, nuclear envelopes reform, the chromosomes uncoil and lengthen, and nucleoli reappear.
Two genetically identical daughter nuclei are formed
Cytokinesis follows

26. Cytokinesis Division of the cytoplasm Occurs along with telophase
Two daughter cells separate
Difference in animal and plant cells
Animal Cell cell membrane pinches off to form a cleavage furrow
Plant Cell Cell plate is formed to divide cell into two

27. Animal Cell

28. Plant Cell

29. Regulating the Cell Cycle
Cell division is affected by
Cell Density
Anchorage
Regulatory Proteins

30. Density dependent inhibition
Cultured cells normally divide until they form a single layer on the inner surface of the culture container
If a gap is created, the cells will grow to fill the gap.

31. Anchorage dependence
Cells must be anchored to a substratum, typically the extracellular matrix of a tissue.
Cancer cells are free of both density-dependent inhibition and anchorage dependence.

32. Regulatory Proteins Regulatory proteins Fluctuates during cell cycle
Cyclins timing of the cell cycle
Regulatory proteins
Internal
External  growth factors
Fluctuates during cell cycle

33. Growth Factors Coordination between cells
protein signals released by body cells that stimulate other cells to divide
Body has many different types
Each stimulates only cells with that type of receptor

34. Apoptosis Programmed cell death
Apoptotic cells shrink in size, break into smaller pieces called apoptotic bodies that other body cells recognize and eat.

35. What Causes Cancer?
Cells do not have a properly functioning “cell cycle” control system
Cells divide excessively and result in an abnormal mass of cells
tumor-suppressor genes  gene p53
inhibits cell division
if switched “OFF” can cause cancer

36. Growth Factors and Cancer
Growth factors can create cancers
proto-oncogenes
normal growth factor genes that become oncogenes (cancer-causing) when mutated
stimulates cell growth
if switched “ON” can cause cancer
example: RAS (activates cyclins)
tumor-suppressor genes
inhibits cell division
if switched “OFF” can cause cancer
example: p53

37. Tumors and Cancer Benign mass of normal cells Malignant
Can be removed surgically
Always remain at their original site
Malignant
Mass of cancer cells
Spread to other tissues by entering the circulatory system
Metastasis  spread of cancer cells beyond site

38. Types of Cancer
Carcinoma  external or internal coverings of the body-skin, intestinal linings
Sarcoma bone and muscle
Leukemia and Lymphoma- blood forming tissues

39. Treatment of Cancer Surgery
Radiation therapy high energy radiation disrupts cell division
Chemotherapy drugs that inhibit cell division
Side effects:
Radiation can lead to sterility
Chemotherapy can cause nausea, hair loss