1. Cell Growth and Reproduction

2. Limits to Cell Growth
Two reasons cells cannot continue to grow larger indefinitely:
(1) The larger a cell becomes, the more demands the cell places on its DNA. As cell gets bigger, it does not make extra copies of DNA.
(2) Cell has more trouble moving enough nutrients and wastes across the cell membrane.

3. Cell Reproduction
Before it becomes too large, a growing cell divides forming two “daughter” cells.
The process by which a cell divides into two new daughter cells is called cell division.

4. Cell Division
The Cell Cycle is a series of events a cell goes through as it grows and divides.

5. Cell Division
Before the cell divides, it must first copy its genetic information before cell division begins.
Two stages for cell division:
(1) mitosis – division of the nucleus
(2) cytokinesis – division of the cytoplasm

6. Mitosis
Reproduction by mitosis is asexual, because the daughter cells are genetically identical to the parent cell

7. Chromosomes
Chromosomes are composed of DNA and proteins and pass genetic information from one generation to the next
Humans have 46 chromosomes (23 pairs). One of each pair from mom and one from dad

8. Chromosomes
Chromosomes are visible only during cell division, when they condense into compact, tightly coiled structures

9. Chromosome VS Chromatid
Before cell division occurs, each chromosome is replicated or copied. Because of this, each chromosome has two identical “sister” chromatids.
When the cell divides the sister chromatids separate from each other, so that one chromatid goes into each of the new cells

10. Chromosomes
In humans, only chromosome pairs reproduce via mitosis, because these chromosomes include somatic (body) cells. Examples of somatic cells include: muscle, blood, bone, and skin cells.

11. Chromosomes
The purpose of mitosis in multicellular organisms is growth and repair of damaged tissues. The purpose of mitosis in unicellular organisms is replication (creating a new organism).

12. Cell Cycle
The cell cycle is the series of events that cells go through as they grow and divide
Consists of 4 phases:
1. M phase – mitosis and cytokinesis
2. S phase – chromosome replication
3. G1 and G2 phases – “gaps” of time with intense growth and activity

14. Interphase Consists of three phases: 1. G1 phase 2. S phase

15. G1 Phase
The G1 phase is a period of activity in which cells do most of their growing. Cells increase in size and synthesize new proteins and organelles.

16. S phase
The S phase is a period in which chromosomes are replicated and the synthesis of DNA (DNA replication) occurs

17. G2 Phase Shortest of the three phases of interphase
Many organelles and molecules required for cell division are produced.
When G2 phase is over, cell is ready to enter M phase and begin cell division

19. Mitosis – time of cell reproduction
Mitosis process can last from a few minutes to several days. Four phases included:
Prophase
Metaphase
Anaphase
Telophase

20. Prophase Prophase is the longest phase of mitosis
Chromatin condenses into chromosomes
Nuclear envelope dissolves
Centrioles move to poles
Spindle fibers form
Centromere = Center of chromosome
Centrioles = organize spindle, that will help separate chromosomes during division
Spindle = microtubules that guide chromosomes

21. Prophase

22. Metaphase - short Chromosomes line up at the equator
Microtubules connect centromere to spindle

23. Anaphase
Centromeres split and sister chromatids separate to become individual chromosomes

24. Telophase
Chromosomes uncoil and nucleus reappears

25. Cytokinesis
Cytokinesis = division of cytoplasm making 2 new daughter cells
Animal cells
Plasma membrane pinches along equator
Forms 2 new cells
Plant Cells
Cell plate laid across equator
Cell membrane forms around each cell
New cell walls form

27. Results of Mitosis
2 new cells with identical chromosomes as parent cell
Unicellular organisms
Organism multiplied
Multicellular organisms
Cell growth and reproduction
Tissue – groups of cells that work together
Organs – tissues organize in various combos
Organ Systems – multiple organs

28. Cancer Malignant growth resulting from uncontrolled cell division
May be caused by environmental factors
Or by changes of enzyme production
Genes are segments of DNA that controls the production of a protein portion just before DNA replication. This is the key control period

29. Cancer: Mistake in Cell Cycle
Form masses of tissues called tumors – deprive normal cells of nutrients
Cancer cells enter circulatory system and spread – form new tumors
2nd leading cause of death
1st heart disease

30. Cause Genetic and environmental Different countries different types
Cigarette smoke
Air and water pollution
UV rays
Viral infections

31. Prevention Life Healthy Lifestyle Diets low in fat and high in fiber
Fruits, veggies, grain products
Vitamins and minerals
A,C,E, Calcium
Exercise