1. Cell Growth and reproduction chapter 5
Anna Morrison

2. Energizer Getting Through
Materials move through cells by diffusion. Oxygen and food move into cells while waste products move out of cells. How does the size of a cell affect how efficiently materials get to all parts of a cell?
Work with your partner. One of you draw a square 2 inches by 2inches. Your partner will draw one half of this size. How much longer do you think it would take to get from the cell membrane to the center of your square compared to that of your partner? What is the advantage of cells being small?

3. Recall: The Cell Theory
All living organisms are composed of one or more cells. Cells are the smallest unit of living organisms. Cells arise only from previously existing cells.
How does this apply to cell growth and reproduction?
Cells have to have an organized way to reproduce and grow if they are going to make up ALL living organisms!

4. What Limits the Size of a Cell?
Ratio of surface area to volume
Surface area is the area covered by the cell (plasma) membrane
Volume refers to the space taken by the inner contents of the cell (organelles in the cytoplasm and the nucleus)

5. Where does the cell cycle occur?
The cell cycle occurs in eukaryotic cells.
Prokaryotic cells undergo binary fission.

6. Interphase G1: cell grows, carries out normal cell functioning
S: cell copies (duplicates) its DNA
Chromosomes: structures that contain the genetic information that is passed from generation to generation of cells
Chromatin: the relaxed form of DNA in the cell’s nucleus
G2: cell prepares for division of the nucleus and “takes inventory”

7. Mitosis
Mitosis includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis)
Mitosis occurs only if the cell is large enough and the DNA is undamaged.

8. Cells divide at different rates
The rate of cell division varies with the need for those types of cells.
Some cells are unlikely to divide (G0).

9. Surface Area to Volume Ratio
Volume increases faster than surface area.

10. Surface Area to Volume Ratio
Since the volume increases much more rapidly than the surface area, the cell might have difficulty supplying nutrients and expelling enough waste products.
The cell’s small size allows it to SUSTAIN itself more readily.
Diffusion over large distances is slow and inefficient because it relies on random movement of molecules and ions.

11. IT STOPS GROWING OR DIVIDES!
Cell Cycle
What happens when a cell reaches its size limit?
IT STOPS GROWING OR DIVIDES!

12. Mitosis
During mitosis, the cell’s replicated genetic material separates and the cell prepares to divide into two cells.
Accurate separation of the cell’s replicated DNA allows the genetic information to pass into the new cells intact.

13. Chromosomes Chromosomes condense at the start of mitosis.
DNA wraps around proteins (called histones) that condense it.
DNA double helix
DNA and histones
Chromatin
Supercoiled DNA

14. Chromosomes DNA plus proteins is called chromatin.
chromatid
telomere
centromere
Condensed, duplicated chromosome
DNA plus proteins is called chromatin.
Chromosomes are shaped like an X
Each half of this X is called a sister chromatid
Contains identical copies of DNA
Sister chromatids are held together at the centromere
Telomeres protect DNA and do not include genes

15. Mitosis: Prophase
During prophase, chromatin condenses into tightly coiled chromosomes.

16. Mitosis: Prophase
As prophase continues, the nucleolus seems to disappear.
Microtubules, called spindle fibers, form in the cytoplasm.
In animal cells, centrioles (microtubles) migrate to the poles of the cells.

17. Mitosis: Metaphase
During metaphase, the chromosomes line up in the middle, or equator, of the cell.

18. Mitosis: Anaphase
During anaphase, sister chromatids separate to opposite sides of the cell.

19. Mitosis: Telophase
During telophase, the new nuclei form and chromosomes begin to uncoil, relax, or decondense.

20. Mitosis: Cytokinesis
After mitosis is complete, during cytokinesis, the cell divides the cytoplasm and forms two identical daughter cells.
Cytokinesis differs in plant and animal cells.
In animal cells, the membrane pinches closed.
In plant cells, a cell plate forms.

21. Binary fission is similar in function to mitosis.
Asexual Reproduction
Asexual reproduction is the creation of offspring from a single parent.
Binary fission produces two daughter cells genetically identical to the parent cell.
Binary fission occurs in prokaryotes.
parent cell
DNA
duplicates
cell begins
to divide
daughter
cells

22. Asexual Reproduction
Environment determines what form of reproduction is most advantageous.
Asexual reproduction is an advantage in consistently favorable conditions.
Sexual reproduction is an advantage in changing conditions.

23. Some eukaryotes reproduce through mitosis.
Asexual Reproduction
Some eukaryotes reproduce through mitosis.
Budding forms a new organism from a small projection growing on the surface of the parent.
bud
Hydra
Yeast

24. Asexual Reproduction
Fragmentation is the splitting of the parent into pieces that each grow into a new organism.
Vegetative reproduction forms a new plant from the modification of a stem or underground structure on the parent plant.

25. Multicellular organisms depend on interactions among different cell types.
vascular
tissue
leaf
stem
lateral
roots
primary
root
SYSTEMS
root system
shoot system
Tissues are groups of cells that perform a similar function.
Organs are groups of tissues that perform a specific or related function.
Organ systems are groups of organs that carry out similar functions.
CELL
TISSUE
ORGAN

26. Specialized cells perform specific functions.
Cells develop into their mature forms through the process of cell differentiation.
Cells differ because different combinations of genes are expressed.
A cell’s location in an embryo helps determine how it will differentiate.
Outer: skin cells
Middle: bone cells
Inner: intestines

27. Stem cells are unique body cells.
Stem cells have the ability to
divide and renew themselves
remain undifferentiated in form
develop into a variety of specialized cell types

28. Multicellular Life Stem cells are classified into three types.
totipotent, or growing into any other cell type
pluripotent, or growing into any cell type but a totipotent cell
multipotent, or growing into cells of a closely related cell family

29. Multicellular Life Stem cells come from adults and embryos.
Adult stem cells can be hard to isolate and grow.
The use of adult stem cells may prevent transplant rejection.
The use of embryonic stem cells raises ethical issues
Embryonic stem cells are pluripotent and can be grown indefinitely in culture.
First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming an inner cell mass. These cells are then removed and grown with nutrients. Scientists try to control how the cells specialize by adding or removing certain molecules.

30. Multicellular Life
The use of stem cells offers many currently realized and potential benefits.
Stem cells are used to treat leukemia and lymphoma.
Stem cells may cure disease or replace damaged organs.
Stem cells may revolutionize the drug development process.