1. Cell Growth and Division

2. Cell Size 8 micrometers in diameter to 1 meter with small diameters.
Most cells are between 2 and 200 micrometers in diameter.
Human Body:
Smallest: sperm cells
Largest: ovum
Longest: nerve cells
Largest Living Cell- Ostrich Egg (unfertilized)

3. Comparison of Cell sizes

4. Cell Size Limitations Cell must be small Rate of Diffusion
Large need more food
Must export waste
Rate of Diffusion
Size :diffusion slower and less efficient.
DNA (molecule where critical information stored) Too large “Information Crisis”
Cell cannot survive unless
enough DNA to support protein needs
cell activities are carried out quickly and efficiently

5. Cell Size Increase
Not enough cell membrane to adequately supply the cell interior with enough oxygen, water, and food.
Result: Cell Death

6. Surface area-to-volume ratio
As cell’s size increases, its volume increases much faster than its surface area.

7. Surface Area and Volume
Surface Area: 6 (# of sides) x A x A
Volume: A x A X A
Cube doubled
Outside Grows by 4 x
Inside grows by 8 x

10. Cell Growth and Reproduction

11. Asexual Versus Sexual Reproduction
Genetically identical offspring
Single Cell
ex. Bacteria
Multi Cellular- Break off and new organism produced
ex. Hydra
Offspring inherit genetic information from each parent.
Most plants and animals, some single celled organisms.

12. Asexual Versus Sexual Reproduction
Survival Strategy
Better the conditions the faster reproduce, better chance of survival,
As long as conditions favorable; genetically identical has advantages
Lack of diversity a disadvantage when conditions change and are not favorable.
Different survival strategy
Finding a mate, growth and development take more time.
Genetic diversity; better tolerate change

13. Both Sexual and Asexual
Ex. Yeast
Mostly asexual, however, may under certain conditions reproduce sexually.

14. Cell Theory All cells come from pre-existing cells
Cell Theory All cells come from pre-existing cells! Cell division results in two cells that are identical to the original parent cell.

15. Prokaryotic Cells Lack nucleus & many organelles
DNA molecule found in cytoplasm
Most contain single, circular DNA with all genetic information

16. Chromosomes Chroma (Greek) “colored”
Chromosomes Chroma (Greek) “colored” Soma “body” Genetic information is bundled into packages of DNA

17. Structure of the Eukaryotic Chromosome
Exist as CHROMATIN—Long strands of DNA wrapped around proteins.
Microscope—Plate of spaghetti

19. Components
Sugar-Deoxy-ribose –derived from ribose sugar-one less oxygen
Phosphate Group -backbone
4 Nitrogen Bases-In complementary base pairs held by hydrogen bonds
Adenine & Thymine
Cytosine &Guanine

20. Chromosomes
Make it possible to separate DNA precisely during cell division

21. A series of events the cells go through as they grow and divide
During cell cycle, a cell grows, prepares for division, and divides to form two daughter cells.
Cell Cycle

22. Prokaryotic Cell Cycle
Regular pattern of growth, DNA replication, and cell division that can take place under ideal conditions
Just beginning to understand process
Form of reproduction called Binary Fission.
Result-two genetically identical cells.

23. Cell Cycle Interphase-Period of cell cycle b/w cell division
most of the cell’s metabolic functions are carried out
chromosomes are replicated
LONGEST of Cell Cycle
Cell Division (M Phase)
Mitosis when nuclear division occurs, leading to the formation of two daughter cells.
The division of the cytoplasm, called cytokinesis, follows mitosis.
Length of cell cycle depend on the type of cell

24. Eukaryotic Cell Cycle

25. Interphase: Cell prepares for Mitosis
Cell grows in size
Carry on metabolism
Chromosomes are duplicated for cell division.

26. Interphase G1 Phase: Cell Growth Most cell growth Increase in size
Synthesize new proteins and organelles

27. Interphase Continued S Phase G2 Phase: Preparing for Cell Division
“S” Synthesis
DNA is synthesized when chromosomes replicated.
Result: Cell has 2x as much DNA
Shortest phase of Interphase
Organelles and molecules required for cell division are produced.
Result: Cell ready for division

28. Helicase-(Enzyme) unzips/breaks hydrogen bonds b/w base pairs
Nitrogen Bases

30. M Phase Produces 2 daughter cells “M” comes from Mitosis
Cell division relatively quick
Includes Mitosis and Cytokinesis
Mitosis-division of the cell nucleus
2 daughter cells produced with genetic information
Cytokinesis-division of the cytoplasm

31. Mitosis: A period of nuclear division

32. Mitosis Interphase Mitosis Cytokinesis Prophase Metaphase Anaphase
Telophase
Cytokinesis

33. Prophase 1st / longest phase of mitosis.
Chromatin coils up (condenses)-chromosomes.
Duplicate chromosomes become visible
Two halves of the double structure are called sister chromatids. (Exact Copies of each other)
Centromere—holds together sister chromatids.

34. Prophase continued… Nucleus disappears
Nuclear envelope and nucleolus disintegrate.
Animals—centrioles migrate to opposite end of the cell.
Centriole—Small, dark, cylindrical structures that are made of microtubules and are located just outside the nucleus.(animal cells only)

35. Prophase continued…
Spindle—A football shaped, cage-like structure consisting of thin fibers made of microtubules.

36. Metaphase: Second stage of mitosis
Chromosomes
Line up at center of cell
Attach to the spindle fibers via centromeres.
Pulled by spindle fibers and line up on the midline (equator).
One sister chromatid’s spindle fiber extends to one pole, and the other extends to the opposite poles (ensures a complete set of chromosomes)

37. Anaphase: Third Phase of Mitosis
Separation of sister chromosomes
Centromeres split apart and chromatid pair separate
Pulled apart by the shortening of the microtubules in the spindle fiber.

38. Telophase: 4th phase of mitosis
Chromosomes reach opposite poles of cell.
Prophase changes are reversed (independent existence).
Chromosomes unwind; Spindle breaks down; nucleolus reappears; new nuclear envelope forms each set of chromosomes; new double membrane begins to form.

39. Cytokinesis Cytoplasm division
Animal Cells—Membrane is drawn inward until the cytoplasm is pinched into two nearly equal parts.
Plant Cells—(cell membrane not flexible enough to draw inward because of rigid cell wall) Cell plate forms b/w the divided nuclei. Gradually, cell plate develops into cell membrane that separates two daughter cells.

40. Result of Mitosis
Two new cells with chromosome sets identical to those of the parents; Carry out same function of parent cells; Grow and divide like parent cells.
Tissues: group of cells that work together to do a specific function.
Organs: group of two or more tissues organized to perform complex activities within an organism.
Organ Systems: Multiple organs that work together to perform specific life function.

42. Cell Cycle

43. Purpose of Cell Division and Mitosis
Keep total cell number in a mature organism relatively constant,
Replace worn-out or damaged cells,
Enable a multicellular organism to grow to adult size.

45. A mistake in the cell cycle can lead to cancer.
Control of Cell Cycle
Cell cycle
24 to 48 hours
less then an hour
never divide only mature
Most muscle and nerve never divide
A mistake in the cell cycle can lead to cancer.

46. Cell Regulation
Injury occurs-cells divide rapidly, healing process begins, as near completion, slows down, everything returns to normal
Cyclin-a protein that regulates timing of cell cycle
Regulatory Proteins-Proteins that control cell cycle (both inside and outside cell)
Functions: slow down or stop cell division, start cell division, etc
Internal Regulators- allow cell to proceed only when certain events have occurred
External Regulators-Respond to events outside cell.
Growth factors-stimulate growth and division of cells.

47. Control of the Cell Cycle
Enzymes
Begin and drive the cell cycle
Control the cycle through its phases.
Cell can lose control (uncontrolled dividing)
failure to produce certain enzymes
production of other enzymes at the wrong time.
Cancer is the result of uncontrolled cell division.

48. Cell Death Death due to injury
Apoptosis-Cell may be programmed to die (self-destruction)
Controlled steps to death
Cell and its chromosomes shrink
Parts of cell membrane break off
Neighboring cells clean up cell’s remains

49. Causes of loss of control of cell cycle
Environmental Factors
Changes in enzyme production
Enzyme production is directed by genes located on the chromosome.
A gene is a segment of DNA that controls the production of a protein.
Many studies point to portion of interphase just before DNA replication as being a key control period.

50. Cancer: A mistake in the Cell Cycle
Expressed as cancer when something prompts the damaged genes into action.

52. Cancer
Cancerous cells form masses of tissue called tumors that deprive normal cells of nutrients.
Late Stages: Cancer cells enter the circulatory system and spread throughout the body (Metastasis), forming new tumors that disrupt the function of organs, organ systems, and ultimately the organism.
Breast Cancer
Brain cancer
Virus attacking
Cancer Cell

53. In Cancer Cells
There is no awareness of surroundings.
Cells do not stop dividing when crowded.
Cells do not stop after a set number of divisions.
Cells do not enter a resting state.
Cells divide faster and take less time to complete the cycle.

54. Cancer: 2nd Leading Cause of death in the United States (heart disease #1)
Environmental and Genetic Factors
Cigarette smoke
Air
Water pollution
Exposure to UV Radiation
Viral Infections
p53 (gene halts cell cycle)

55. Treatments Surgery (tumor removal)
Chemotherapy-Chemical compounds that kill cancer cells and/or slow growth
Interfere with healthy cells
Serious side effects
Radiation

56. Cancer Prevention
Link between healthy lifestyle and the incidence of cancer.
Diets low in fat and high in fiber.
Minimal amounts of fat.
Vitamins and minerals; carotenoids, vitamins A, C, and E and calcium.
Daily exercise
No smoking

58. Cell Differentiation Human body-estimated one hundred trillion cells.
Embryo-developmental stage of a multicellular organism; organism's cells become more and more differentiated and specialized for specific function.

62. Differentiation
During development of an organism, cells differentiate into many types of cells
9959 cell with precisely determined functions

63. Stem Cells and Development
Totipotent-cells that are able to develop into any type of cell found in the body.
Blastocyst- after about 4th day of development human embryo forms; a hollow ball of cells with a cluster of cells inside (inner cell mass); differentiation occurs
Outer cells form tissue that will attach to mom
Inner cells mass becomes the embryo

64. Pluripotent Cells
Cells that can develop into MOST, but not all, of body’s cell types.
Ex. Inner cell mass (can not form tissues surrounding embryo

65. Unspecialized cells from which differentiated cells develop
Stem Cells
Unspecialized cells from which differentiated cells develop

66. Stem Cells Embryonic Stem Cells-found in early embryos
1998 researchers from way to grow in culture
Can make different types of cells; sperm made from embryonic stem cells were used to generate live mice.

68. Adult Stem Cells
Cells that differentiate to renew and replace cells in the adult body-limited potential
Multipotent-cells that can develop into many types of differentiated cells.
Most only produce type of cells of given organ or tissue
Eg-adult stem cells in bone marrow can develop into several types of blood cells; while brain stem cells can produce neurons (nerve cells)

70. Frontiers in Stem Cell Important to human health
Use of undifferentiated cells to repair or replace badly damaged cells and tissues.
Ethical Issues
Embryonic stem cells (from early embryos)
Embryo‘s entitled to rights and protections of human beings.
Government funding-political issue
Ethical issue of life and death
Technology solutions becoming available