1. Asexual vs. Sexual Reproduction

2. Asexual Reproduction
Asexual reproduction: production of offspring by 1 parent
New cells are IDENTICAL to parent cell

3. Asexual Reproduction Advantages
Takes less time and energy
Don’t have to find a mate; takes only 1 parent
More likely to survive in a stable environment

4. Sexual Reproduction
Sexual reproduction: production of offspring by combining genetic information from 2 parents

5. More likely to survive in a changing environment
Sexual Reproduction
Advantages
Genetic variation
More likely to survive in a changing environment

6. Chromosomes

7. DNA & Chromosome Structure
DNA is a long molecule and unwound it is called chromatin
DNA can wind up to become chromosomes
Chromatin  chromosome right before cell division

8. Chromosome Structure Uncopied chromosome
Copied chromosome contains 2 sister chromatids
Sister chromatids are IDENTICAL to one another
Held together by a centromere

9. Chromosome Number Each species has a specific number of chromosomes
Humans have 46 chromosomes or 23 pairs
Each pair is called a homologous pair
1 from mom, 1 from dad
Homologous chromosomes carry the same genes

11. Chromosome Number
Cells that have a full set of chromosomes are diploid cells (2N).
All body (somatic) cells are diploid.
Cells that have a half set of chromosomes are haploid cells (N).
All gametes (sperm and egg) are haploid.

12. Cell Division

13. What do you see happening?
Lung cell:
Animation:
What must happen before the cell divides?

14. The Cell Cycle Cell cycle is the life cycle of a cell
Broken into 2 phases:
Interphase
M phase

15. Events of the Cell Cycle
Interphase is made up of 3 sub-phases:
G1: cell grows
S: DNA copies
G2: cell grows and prepares for division

16. Events of the Cell Cycle
M phase is made of 2 sub-phases:
Division of the nucleus & DNA
Cytokinesis: division of the cytoplasm

17. Events of the Cell Cycle

18. Interphase (before Mitosis)
Section 10-2
Spindle forming
Centrioles
Chromatin
Centromere
Nuclear envelope
Centriole
Chromosomes (paired chromatids)
Interphase
Prophase
Spindle
Cytokinesis
Centriole
Metaphase
Telophase
Individual chromosomes
Cell growth
DNA replicates
Anaphase
Nuclear envelope reforming

19. Prophase Chromosomes become visible
Section 10-2
Spindle forming
Centrioles
Chromatin
Centromere
Nuclear envelope
Centriole
Chromosomes (paired chromatids)
Interphase
Prophase
Spindle
Cytokinesis
Centriole
Metaphase
Chromosomes become visible
Centrioles separate and spindle fibers form
Nuclear envelope disappears
Telophase
Individual chromosomes
Anaphase
Nuclear envelope reforming

20. Metaphase Metaphase Chromosomes line up in the middle
Section 10-2
Spindle forming
Centrioles
Chromatin
Centromere
Nuclear envelope
Centriole
Chromosomes (paired chromatids)
Interphase
Prophase
Spindle
Cytokinesis
Centriole
Metaphase
Telophase
Individual chromosomes
Anaphase
Chromosomes line up in the middle
Spindle fibers attach at the centromere of each chromosome
Nuclear envelope reforming

21. Anaphase
Section 10-2
Spindle forming
Centrioles
Chromatin
Centromere
Nuclear envelope
Centriole
Chromosomes (paired chromatids)
Interphase
Prophase
Spindle
Cytokinesis
Centriole
Metaphase
Telophase
Individual chromosomes
Anaphase
Nuclear envelope reforming
Sister chromatids separate and move towards opposite ends of the cell

22. Telophase Chromatids are at opposite ends of cell
Section 10-2
Spindle forming
Centrioles
Chromatids are at opposite ends of cell
Nuclear envelope reforms
Nuclear envelope
Chromatin
Centromere
Centriole
Chromosomes (paired chromatids)
Interphase
Prophase
Spindle
Cytokinesis
Centriole
Metaphase
Telophase
Individual chromosomes
Anaphase
Nuclear envelope reforming

23. Cytokinesis (after Mitosis)
Section 10-2
Spindle forming
Centrioles
Chromatin
Centromere
Nuclear envelope
Centriole
Chromosomes (paired chromatids)
Interphase
Prophase
Spindle
Cytokinesis
Centriole
Metaphase
Telophase
Individual chromosomes
Anaphase
Cytoplasm pinches and divides in half
Two identical daughter cells are formed
Nuclear envelope reforming

24. Cell Size and Cell Cycle

25. Why do cells divide? Too much demand on the cells’ DNA
The larger a cell becomes, the more demand the cell places on its DNA.
Difficult to get nutrients and wastes across the cell membrane
A larger cell has trouble moving substances from the membrane to all parts of the cell.

26. DNA “Overload” Cells only have so much DNA.
When they get bigger, they don’t make more DNA.
So if cells grew indefinitely, the DNA wouldn’t be able to meet all its needs.

27. Exchanging Materials
How fast things can be exchanged depends on the surface area of a cell.
How fast waste is made and nutrients are needed depends on volume of a cell.
As cells get bigger, ___________ increases faster than __________ ________.
volume
surface
area

28. So…what do cells do?
Before a growing cell gets too large, it will divide.
This creates 2 daughter cells.
The process is called cell division.

29. The Cell Cycle
Cell cycle: the life cycle of the cell as they grow and divide
Made up of 2 large phases:
Interphase
M phase

30. Regulating the Cell Cycle
In humans, nerve cells and muscle cells do not continue to divide after they have developed.
That is why spinal cord injuries are not repaired.
Other cells divide rapidly throughout life.
Example: skin cells, hair cells, and cells in the bone marrow that make blood cells

31. Cell Cycle Regulators
Internal regulators: respond to events inside the cell
Example: cell cycle only proceeds when certain events have occurred
Cyclin: a group of proteins that regulates the timing of the cell cycle within cells
The sample is injected into a second cell in G2 of interphase.
A sample of cytoplasm is removed from a cell in mitosis.
As a result, the second cell enters mitosis.

32. Cell Cycle Regulators
External regulators: respond to events outside the cell
Example: Growth regulators are important in wound healing.

33. Fertilization & Differentiation

34. Fertilization Fertilization: joining of egg and sperm
Fertilization restores the diploid number!
1st cell is called a zygote

35. What next?
After fertilization, mitosis continues to produce more cells as you grow.
Aging occurs because mitosis slows down
Cells continue to die but are not able to be replaced as quickly.

36. Differentiation of cells
Cells become specialized to make different types of cells.

37. Differentiation of cells
Different types of cells make different proteins because different combinations of genes are active in each type.

38. Why do cells divide? Multicellular organisms use…
Mitosis to grow and heal
Meiosis to sexually reproduce

39. Differentiation and Stem Cells
What do you know about stem cells?

40. Missouri Stem Cell Research and Cures Initiative
In 2006, Missouri passed the Stem Cell Research and Cures Initiative.
This allowed any stem cell research and therapy in Missouri that is legal under federal law, including somatic cell nuclear transfer to produce human embryos for stem cell production
it prohibits cloning or attempting to clone a human being
Do you agree or disagree with this initiative?

41. Control of the Cell Cycle & Cancer

42. Cell Division and Cancer
DNA codes for proteins that regulate cell division.
If DNA is mutated, cell division can occur out of control.
Cancer: uncontrolled cell division

43. Mutations in DNA can cause cancer
Possible mutagens (causes)
High energy radiation (UV & X-rays)
Chemicals
High temperatures
Mistakes in DNA replication
Viruses
Other environmental factors

44. Cancer cells can produce malignant tumors

45. Skin Cancer Application
How does cancer relate to the cell cycle?

46. Accumulation of mutations lead to cancer
Chromosomes
mutation 1 2 3 4
mutations
Normal cell
Malignant cell
Figure 11.18B

52. Dear 16 Year Old Me…

53. Different types of Cell Divisions
Mitosis
Meiosis
Function
Number of chromosomes in parent cell
Number of daughter cells after cell division
Number of chromosomes in each daughter cell
Type of cell produced
Number of times cell divides
Difference in DNA in parent and daughter cells

54. Different types of Cell Divisions
Mitosis
Meiosis
Two daughter cells are formed from each original cell
Four daughter cells are formed from each original cell
Replication of chromosomes occurs
Cells with reduced chromosome numbers are formed
Cells with the same chromosome number as original cell are formed
Results in forming egg or sperm cells
Results in forming somatic (body) cells
Each original cell divides only once
Each original cell divides twice
Chromosomes move to the center of the cell

55. Karyotypes

56. Karyotyping
Karyotyping: a process used to look at an individual’s chromosomes (can be done before birth)

57. Chromosome number A human has 23 pairs of chromosomes
Chromosomes 1-22 are called autosomes
23rd pair is the sex chromosomes

58. Sex Chromosomes The X chromosome The Y chromosome Large in size
Carries many genes on it
Must have 1 X chromosome to live
The Y chromosome
Small in size
Carries few genes that cause development into males
Only males have a Y chromosome

59. Sex Chromosomes X and Y do NOT refer to the shape of the chromosome.
A normal female is XX.
A normal male is XY.

60. Genetic Disorders
Normal cells have pairs of chromosomes.
If a cell has an extra copy of one chromosome, it is called trisomy.
If a cell is missing one copy of a chromosome, it is called monosomy.