1. Essential knowledge 2.E.1:
Timing and coordination of specific events are necessary for the normal development of an organism, and these events are regulated by a variety of mechanisms. a. Observable cell differentiation results from the expression of genes for tissue-specific proteins. b. Induction of transcription factors during development results in sequential gene expression. c. Programmed cell death (apoptosis) plays a role in the normal development and differentiation.

2. Essential knowledge 3.A.2:
In eukaryotes, heritable information is passed to the next generation via processes that include the cell cycle and mitosis or meiosis plus fertilization. a. The cell cycle is a complex set of stages that is highly regulated with checkpoints, which determine the ultimate fate of the cell. b. Mitosis passes a complete genome from the parent cell to daughter cells. c. Meiosis, a reduction division, followed by fertilization ensures genetic diversity in sexually reproducing organisms.

3. Essential knowledge 3.B.2:
A variety of intercellular and intracellular signal transmissions mediate gene expression.
Signal transmission within and between cells mediates
gene expression.
b. Signal transmission within and between cells mediates
cell function.

4. Essential knowledge 2.D.1:
All biological systems from cells and organisms to
populations, communities and ecosystems are affected by complex biotic and abiotic interactions involving exchange of matter and free energy.
Cell activities are affected by interactions with biotic and abiotic factors.
b. Organism activities are affected by interactions with
biotic and abiotic factors.
c. The stability of populations, communities and ecosystems is affected by interactions with biotic and abiotic factors.

5. Essential knowledge 3.C.2:
Biological systems have multiple processes that increase genetic variation. a. The imperfect nature of DNA replication and repair increases variation. b. The horizontal acquisitions of genetic information primarily in prokaryotes via transformation (uptake of naked DNA), transduction (viral transmission of genetic information), conjugation (cell-to-cell transfer) and transposition (movement of DNA segments within and between DNA molecules) increase variation. c. Sexual reproduction in eukaryotes involving gamete formation, including crossing-over during meiosis and the random assortment of chromosomes during meiosis, and fertilization serve to increase variation. Reproduction processes that increase genetic variation are evolutionarily conserved and are shared by various organisms.

6. Essential knowledge 3.D.4:
Changes in signal transduction pathways can
alter cellular response.
Conditions where signal transduction is blocked or defective can be deleterious, preventative or prophylactic.

7. Mitosis in Animal and Plant Cells The Cell Cycle & Cancer
Outline
The Cell Cycle
Interphase
Mitotic Stage
Cell Cycle Control
Apoptosis
Mitosis & Cytokinesis
Mitosis in Animal and Plant Cells
The Cell Cycle & Cancer
Prokaryotic Cell Division

8. Just prior to next division:
The Cell Cycle
An orderly set of stages and substages between one division and the next
Just prior to next division:
The cell grows larger
The number of organelles doubles
The DNA is replicated
The two major stages of the cell cycle:

9. Interphase Most of the cell cycle (up to 90%) is spent in interphase
G1 Phase:
Recovery from previous division
Cell doubles its organelles
Accumulates raw materials for DNA synthesis
S Phase:
DNA replication (synthesis)
Chromosomes enter with 1 chromatid each
Chromosomes leave with 2 identical chromatids each
G2 Phase:
Between DNA replication and onset of mitosis

10. Interphase
Nerve cells and muscle cells do not complete cell cycle, don’t continue to divide
Cells are said to be arrested in the G0 stage
This is when a cell is performing it’s normal functions

11. Mitotic (M) Stage Includes: Mitosis (karyokinesis) Cytokinesis
Nuclear division
Daughter chromosomes distributed to two daughter nuclei
Cytokinesis
Cytoplasm division

12. Cell cycle controlled by internal and external signals
Growth factors
Received at the plasma membrane
Internal signals
Family of proteins called cyclins
Increase and decrease as cell cycle continues
Without them cycle stops at G1, M or G2
Allows time for any damage to be repaired

13. Cells do not usually divide unless signaled by other cells to do so
Cell-cycle control system is a cyclically operating set of proteins that triggers and coordinates major events of cell cycle

14. The Cell Cycle Control System
The sequential events of the cell cycle
Are directed by a distinct cell cycle control system, which is similar to a clock

15. The clock has specific checkpoints
Where the cell cycle stops until a go-ahead signal is received

16. These control points occur during G1, G2 and M phase of cell cycle
The control system receives intracellular signals telling it that key processes are completed and to proceed
Control system also receives extracellular messages to tell if signal molecules of other cells are present, and general environmental conditions
Signal transduction is a series of molecular changes that converts a signal on target cell’s surface into a specific response inside the cell

17. Often defined as programmed cell death
Apoptosis
Often defined as programmed cell death
Mitosis and apoptosis are opposing forces
Mitosis increases cell number
Apoptosis decreases cell number
Cells harbor apoptosis enzymes (caspases)
Ordinarily held in check by inhibitors
Signal protein P53
Stops cycle at G1 when DNA damaged
Initiates DNA attempt at repair
If successful, cycle continues to mitosis
If not, apoptosis is initiated

18. Mitosis: Preparation DNA is in very long threads
Chromosomes
Stretched out and intertangled between divisions
DNA is associated with histone proteins
Before mitosis begins:
Chromatin condenses (coils) into distinctly visible chromosomes
Each species has a characteristic chromosome number
Humans 46
Corn 20
Goldfish 94

19. Most familiar organisms diploid Have two chromosomes of each type
Chromosome Number
Most familiar organisms diploid
Have two chromosomes of each type
Humans have 23 different types of chromosomes
Each type is represented twice in each body cell (Diploid = 2n)
Only sperm and eggs have one of each type (haploid = 1n)
# of different pairs of chromosomes
The n number for humans is n=23
Two representatives of each type
Makes a total of 2n=46 in each nucleus
One set of 23 from individual’s father (paternal)

20. Chromosome Structure At end of S phase:
Each chromosome internally duplicated
Consists of two identical DNA chains
Sister chromatids
Attached together at a single point (centromere)
During mitosis:
Centromeres holding sister chromatids together simultaneously break
Sister chromatids separate
Each becomes a daughter chromosome

21. Each duplicated chromosome has two sister chromatids with identical genes, which separate during cell division

22. Mitosis in Animal Cells
Just outside nucleus is the centrosome
This is the microtubule organizing center
Organizes the mitotic spindle
Contains many fibers
Each composed of a bundle of microtubules
In animals, contains two barrel-shaped centrioles
Oriented at right angles to each other within centrosome
Each with 9 triplets of microtubules arranged in a cylinder

23. Mitosis consists of four (five) distinct phases
Prophase
Prometaphase

24. Metaphase
Anaphase
Telophase

25. Mitosis in Animal Cells: Prophase
Chromatin has condensed
Chromosomes distinguishable with microscope
Visible as double chromosome (two sister chromatids attached at centromere)
Nucleolus disappears
Nuclear envelope disintegrates
Spindle begins to take shape
Form microtubules in star-like arrays – asters

26. Biology, 9th ed,Sylvia Mader
Chapter 09
Prophase
The Cell Cycle
Chromatin coils and condenses to form chromosomes
Nuclear envelope dissolves
Spindle forms as microtubules grow out from centrosomes (centriole + cytoplasmic material)

27. Mitosis in Animal Cells: Prometaphase
Centromere of each chromosome develops two kinetochores
Specialized protein complex
One over each sister chromatid
Physically hook sister chromatids up with specialized microtubules (kinetochore fibers)

28. Mitosis in Animal Cells: Metaphase & Anaphase
Chromosomes are pulled around by kinetochore fibers
Forced to align across equatorial plane of cell
Appear to be spread out on a piece of glass
Metaphase plate
Represents plane through which mother cell will be divided
Anaphase
Sister chromatids separate
Now called daughter chromosomes
Pulled to opposite poles along kinetochore fibers

29. Some spindle microtubules
Attach to the kinetochores of chromosomes and move the chromosomes to the metaphase plate

30. Biology, 9th ed,Sylvia Mader
Chapter 09
Metaphase
The Cell Cycle
Chromosomes move to center of cell and centromeres line up along the equator
Spindle fibers extend from poles to the centromere of each chromosome (Mitotic spindle formed)

31. Mitosis in Animal Cells: Telophase
Spindle disappears
Now two clusters of daughter chromosomes
Still two of each type with all types represented
Clusters are incipient daughter nuclei
Nuclear envelopes form around the two incipient daughter nuclei
Chromosomes uncoil and become diffuse chromatin again

32. Biology, 9th ed,Sylvia Mader
Telophase
Chapter 09
The Cell Cycle
Cell elongates
Nuclear envelope reforms around chromosomes located at each pole to form daughter nuclei, nucleoli reappear
Chromosomes uncoil
Spindle dissolves
Cytokinesis begins

33. Mitosis produces two genetically identical diploid cells
Used for growth and development, repair and regeneration, and asexual reproduction

34. Cytokinesis: Animal Cells
Division of cytoplasm
Allocates mother cell’s cytoplasm equally to daughter nucleus
Encloses each in it’s own plasma membrane
Often begins in anaphase
Animal cytokinesis:
A cleavage furrow appears between daughter nuclei
Formed by a contractile ring of actin filaments
Like pulling on a draw string

35. Cytokinesis: Plant Cells
Rigid cell walls outside plasma membrane do not permit furrowing
Begins with formation of a cell plate
Many small membrane-bounded vesicles
Eventually fuse into one thin vesicle extending across the mother cell
The membranes of the cell plate become the plasma membrane between the daughter cells
Contents of vesicles become the middle lamella between the two daughter cells

36. The Cell Cycle and Cancer
Abnormal growth of cells is called a neoplasm
Benign neoplasms are not cancerous
Encapsulated
Malignant neoplasms are cancerous
Not encapsulated
Readily invade neighboring tissues
May also detach and lodge in distant places – metastasis
Results from mutation of genes regulating the cell cycle
Carcinogenesis – development of cancer
Tends to be gradual
May be years before cell is obviously cancerous

37. Characteristics of Cancer Cells
Lack differentiation
Have abnormal nuclei
Form tumors
Mitosis controlled by contact with neighboring cells – contact inhibition
Cancer cells have lost contact inhibition
Undergo metastasis
Original tumor easily fragments
New tumors appear in other organs
Undergo angiogenesis (vascularization)

38. Cancer cells
Exhibit neither density-dependent (contact) inhibition nor anchorage dependence

39. In density-dependent (contact) inhibition
Crowded cells stop dividing
Most animal cells exhibit anchorage dependence
In which they must be attached to a substratum to divide

40. Malignant tumors invade surrounding tissues and can metastasize
Exporting cancer cells to other parts of the body where they may form secondary tumors

41. Origins of Cancer: Oncogenes
Mutations in DNA repair mechanisms
Oncogenes
Proto-oncogenes promote the cell cycle in various ways
Tumor suppressor genes inhibit the cell cycle in various ways
Both normally regulated in coordination with organism’s growth plan
Cancer is a disease of the cell cycle – the cell cycle control system functions improperly

42. Normal genes that promote the cell cycle
Proto-oncogenes
Normal genes that promote the cell cycle
May be genes for growth factors, or the receptors for these growth factors
Faulty receptors may stimulate cell cycle without growth factors
Abnormal growth factors may be
“hyperactive” and overstimulate cell cycle

43. Scientists have identified ~ 100 oncogenes
ras oncogenes are frequently involved with cancers

44. Tumor Suppressor Genes
Genes that normally inhibit the cell cycle, often acting as inhibitors of cyclins or proto-oncogenes
When faulty, these genes result in cell cycles going unchecked, and excessive cell division
RB gene is known to be faulty in many types of cancers (inhibits a proto-oncogene)

45. Origins of Cancer: Telomerase
Chromosomes normally have special material at each end called telomeres (end parts)
These get shorter each cell division
When they get very short
The cell will no longer divide
Almost like running out of division tickets
Mutations in telomerase gene:
Keeps adding new telomeres
Allow cancer cells to continually divide
Like counterfeit tickets

46. Prokaryotic Cell Division
Prokaryotic chromosome a ring of DNA
Folded up in an area called the nucleoid region
1,000 X length of cell
Replicated into two rings prior to division
Replicate rings attach to plasma membrane
Binary fission
Splitting in two between the two replicate chromosomes

47. Mitosis in Animal Cells The Cell Cycle & Cancer
Review
The Cell Cycle
Interphase
Mitotic Stage
Cell Cycle Control
Apoptosis
Mitosis & Cytokinesis
Mitosis in Animal Cells
The Cell Cycle & Cancer
Prokaryotic Cell Division