1. DNA Mitosis

2. Key Concepts for DNA Unit
All cells come from other cells, passing on their DNA from parent cell to daughter cell
The cell cycle consists of a series of stages
Mitosis consists of one cell division, produces 2 identical diploid cells, and produces somatic cells for cell growth and repair.
Meiosis produces different haploid sex cells (gametes)
Uncontrolled cell division results from mutations in the DNA and results in cancer

3. Key Terms Mitosis Telophase Meiosis Cytokinesis Haploid Gamete Diploid
Cell Cycle
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Gamete
Somatic Cell
Fertilization
Zygote
Cancer
Carcinogen
Mutation

4. What makes us get bigger?
Do our cells grow larger and larger or do they divide and multiply???
In most cases living things grow by producing more cells.
There’s no real cell size difference between baby and adult animals.
Adults just have many more cells.

5. REVIEW

6. DNA structure DNA is a long chain of simple units called nucleotides
Nucleotides: base, sugar & phosphate

7. Sugar-Phosphate Backbone
Composed of deoxyribose sugar and a simple phosphate molecule
Forms a strong bond that creates the backbone
Exactly the same in all
DNA

8. DNA Structure There are only 4 types of bases in ALL DNA molecules
Adenine, Cytosine, Guanine, and Thymine
Each bond with complimentary bases in other nucleotides to form the rungs of the DNA ladder.
BASE PAIR RULE
Adenine + Thymine
Cytosine + Guanine

9. DNA Structure

10. DNA Form
DNA nucleotides combine in cells to form long strands in the shape of a double helix
The order of the nucleotides is the determining factor in the expression of genes in organisms

11. Characteristics of DNA
DNA accounts for the genetic variation between different organisms by the use of different
Sequences of DNA segments
Lengths of DNA segments
Numbers of chromosomes and amounts of DNA in an organism

12. Characteristics of DNA
DNA replication is the process through which cells copy DNA for transmission to daughter cells during cell division
The double helix structure allows DNA to easily unzip down the center between nitrogenous bases
Free floating nucleotides attach to each of the separated DNA strands forming 2 new strands of DNA, each an exact copy of the original

13. Characteristics of DNA
A mutation is an unexpected change in a DNA sequence, usually occurring during replication/division
Mutations are common in most organisms (especially simple organisms) though only a small percentage produce noticeable changes in organisms

14. Mutations
Often result from increased levels of stress on cells prior to or during cell division
Stress include: radiation, UV rays, environmental

15. Genetic Hierarchy A group of nucleotides= a gene (45-150 base pairs)
A group of genes = 1 strand of DNA
Several condensed strands of DNA = 1 chromosome

16. The Chromosome Chromosome: A compact spool of DNA
Humans have 46 chromosomes
23 from father
23 from mother
Individuals with Downs Syndrome have 1 extra chromosome

17. Chromosome
Chromosomes are important in the mapping of the human genome
Scientists look at chromosomes to diagnose or predict genetic disorders

18. Genetic disorders
A genetic disorder is a disease or other problem resulting from errors in the transmission of genetic information or the expression of certain negative gene sequences

19. Limits to Cell Growth
There are 3 reasons cells divide rather than continue to grow:
The larger the cell becomes, the more demands the cell places on its DNA
Larger cells have more trouble moving things like nutrients and wastes across the cell’s membrane
Repair of damaged tissue

20. Division of the Cell Cells divide before they get too large.
Cell Division — process by which a cell divides into 2 new cells
Each new cell is IDENTICAL to the original and has the same number of chromosomes
Diploid number = 2n (two sets)

21. The original cell is called the parent cell; 2 new cells are called daughter cells
Before cell division occurs , the cell replicates (copies) all of its DNA, so each daughter cell gets complete set of genetic information from parent cell
Each daughter cell is exactly like the parent cell – same kind and number of chromosomes as the original cell
2 Daughter Cells
Parent Cell

22. Many organisms, especially unicellular organisms, reproduce by means of cell division – called asexual reproduction – Ex: bacteria

23. DNA
DNA is located in the nucleus and controls all cell activities including cell division
Long and thread-like DNA in a non-dividing cell is called chromatin
Doubled, coiled, short DNA in a dividing cell is called chromosome
Consists of 2 parts: chromatid and centromere

24. 2 identical “sister” chromatids attached at an area in the middle called a centromere
When cells divide, “sister” chromatids separate and 1 goes to each new cell

25. Coils up into chromosomes
Chromatin to chromosomes illustration:
Chromatin
Coils up into chromosomes
Duplicates itself
Why does DNA need to change from chromatin to chromosome?
More efficient division

26. Chromosome number
Every organism has its own specific number of chromosomes
Examples: Human = 46 chromosomes or 23 pairs
Dog = 78 chromosomes or 39 pairs
Goldfish = 94 chromosomes or 47 pairs
Lettuce = 18 chromosomes or 9 pairs

27. All somatic (body) cells in an organism have the same kind and number of chromosomes
Examples: Human = 46 chromosomes
Human skin cell = 46 chromosomes
Human heart cell = 46 chromosomes
Human muscle cell = 46 chromosomes
Fruit fly = 8 chromosomes
Fruit fly skin cell = 8 chromosomes
Fruit fly heart cell = 8 chromosomes
Fruit fly muscle cell = 8 chromosomes

28. Mitosis – division of the nucleus into 2 nuclei, each with the same number of chromosomes
Mitosis occurs in all the somatic (body) cells
Why does mitosis occur?
So each new daughter cell has nucleus with a complete set of chromosomes

29. Cell Cycle -- series of events cells go through as they grow and divide
Cell grows, prepares for division, then divides to form 2 daughter cells – each of which then begins the cycle again

30. IPMATC “I play music at the concert” Interphase Prophase Metaphase
Anaphase
Telophase
Cytokinesis
I put my alligator there carefully

31. Interphase—period of cell growth and development
DNA replication (copying) occurs during Interphase
During Interphase the cell also grows, carries out normal cell activities, replicates all other organelles
The cell spends most of its life cycle in Interphase

32. 4 phases of nuclear division (mitosis), directed by the cell’s DNA (PMAT)
Prophase
Metaphase—(Middle)
Anaphase—(Apart)
Anaphase—(Apart)
Telophase—(Two)

33. Prophase Longest part of Mitosis Chromosomes become visible
Centrioles near the nuclear envelope move toward opposite poles
Spindle fibers form
Nucleolus disappears and the nuclear envelope breaks down
Centriole

35. Metaphase (middle)
Chromosomes line up across the center of the cell (metaphase plate)
Spindle fibers connect to chromosomes

37. Anaphase (apart) Chromosome copies divide Centromeres split
move toward opposite sides of the cell
- (pulled by spindle fibers)

39. Telophase (two) Chromosomes uncoil Nuclear envelope re-forms
2 New nuclei are formed
Spindle fibers disappear
Mitosis is complete

41. What’s Next? What we’ve got: Final task:
2 nuclei with duplicate chromosomes in the cytoplasm of a single cell
Final task:
Divide the cytoplasm

42. Cytokinesis — the division of the rest of the cell (cytoplasm and organelles) after the nucleus divides
After mitosis and cytokinesis, the cell returns to Interphase to continue to grow and perform regular cell activities

43. Cytokinesis
In animal cells the cell membrane draws inward and is pinched off forming two separate cells
In plants, a cell plate forms between the nuclei, turns into a separating membrane and eventually a cell wall

45. Summary: Cell Cycle
Interphase Mitosis (PMAT) Cytokinesis
When cells become old or damaged, they die and are replaced with new cells

47. Crash Course on Mitosis

48. Controls on Cell Division
Scientists have observed what is “supposed to happen” in petri dishes. Cells should grow until the bottom is covered and then stop. They are also regulated by the surrounding cells.

49. Cell Division Control
DNA controls all cell activities including cell division
Some cells lose their ability to control their rate of cell division – the DNA of these cells has become damaged or changed (mutated)
These super-dividing cells form masses called tumors

50. Cancer is the result of cells not being able control their growth.
Cancer cells DO NOT respond to the signals that regulate the growth of most cells

51. Benign tumors are not cancerous – these cells do not spread to other parts of the body
Malignant tumors are cancerous – these cells break loose and can invade and destroy healthy tissue in other parts of the body (called metastasis)

52. What causes Cancer?
Smoking tobacco, radiation exposure, viral infections
These all have uncontrolled cell growth in common with one another

53. Cancer is not just one disease, but many diseases – over 100 different types of cancers

55. DNA damage vs mutation
DNA damage is distinctly different from mutation, although both are types of error in DNA.
DNA damage is an abnormal chemical structure in DNA, while a mutation is a change in the sequence of standard base pairs.

56. Cancer

57. Chromosome Appearance & Location
Phase
Chromosome Appearance & Location
Important Events
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
DNA replication, cell grows and replicates organelles
DNA copies itself; chromatin
Nuclear envelope disappears, spindle fibers form
Chromosomes coil up
Chromosomes line up in the middle
Spindle fibers connect to chromosomes
Spindle fibers pull chromosome copies apart to opposite poles
Chromosome copies divide and move apart
Nuclear envelopes reform, 2 new nuclei are formed, spindle fibers disappear
Chromosomes uncoil back into chromatin
Division of the rest of the cell: cytoplasm and organelles
Chromatin