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1. Cell Growth and Reproduction Biology Agriculture
2. Cell Growth All cells come in different sizes and shapes.
Diffusion in fast and effective over short distances.
It become slow and inefficient over long distances.
If a cell and a mitochondria 20cm in diameter ? it would take months before it would receive molecules that entered the cell membrane.
3. Cell Growth Surface area-to-volume ratio
Area: the surface included in a set of lines.
Volume: space occupied as measured in cubic inches.
Ratio: the relationship in quantity, amount, or size between two or more things.
4. Cell Growth Due to the surface area-to-volume ratio cells divide before they become to large.
DNA is what directs the cell when it is becoming to large.
5. Cell Reproduction Cell division in necessary to form multi-cellular organisms.
Production of offspring from one parent cell.
Formation of offspring from the union of two gamete cells .
6. Asexual Reproduction Steps:
Chromosomes duplicate (called replication)
Both attach to a site located in the cell
They are forced apart.
Cell membrane constricts them till they separate.
7. Asexual Reproduction Some examples include:
8. Sexual Reproduction Results from the joining of two highly specialized cells.
Ovum Cells or Egg Cell
Sperm cell and ovum combine to form a Zygote.
9. Chromosomes Chromatids:
Long strands of DNA.
Made of two sister chromatids.
Held together by a centromere
10. Diploid (2n) Cells A cell with two of each kind of chromosomes are called Diploid Cells.
11. Haploid (n) Cells A cell with one kind of each chromosome is called a Haploid cell.
12. Mitosis Cells undergo mitosis as they reach their maximum cell size.
There are four steps in mitosis:
13. Mitosis: Stage 1 ? Prophase.
Chromatids coil up into visible chromosomes.
Centrioles migrate to the polar ends of the cell
Spindle Fibers begin to form.
14. Mitosis: Stage 2 ? Metaphase
Chromosomes become attached to the spindle fibers by their centromeres.
They are lined up across the center of the cell.
15. Mitosis: Stage 3 ? Anaphase
Sister chromatids begin to separate
Chromatids are pulled apart, and separate from each other.
16. Mitosis: Stage 4 ? Telophase
New cells prepare for their new existence.
Chromosomes uncoil and direct metabolic activity
Spindle Fibers break down
Double membrane forms between them
17. Mitosis Cytokinesis
Animals ? Plasma Membrane pinches in along the equator of the cell.
18. Mitosis Cytokinesis
Plants - Cell Plate is laid across the equator.
Cell walls form around the plate
19. Results of Mitosis As a result,
Each daughter cell receives and exact copy of the chromosomes present in the parent cell.
They copy their chromosomes during Interphase.
They become a diploid cell 2n
The process can then start over.
20. Results of Mitosis Process that guarantees that genetic continuity.
The two new cells formed will carry out the same functions of the parent cell.
They will grow and divide just like the parent cells.
21. Results of Mitosis As a result of cell division we have groups of cells working together, until they create and organism, i.e.
22. The Cell Cycle Cell Cycle:
The sequence of growth and division in the cell.
A cell goes though two periods:
A period of growth
A period of division
23. The Cell Cycle