Cell Growth and Division

Cell Growth Living things grow chiefly because of two things.  1. The number of cells increases.

 2. The size of each individual cell increases. Number 1 is actually due to number 2!

Volume vs. Area The volume, the growth of the internal parts of the cell surpasses that of the area, or external parts of the cell.

Limits The growth is limited by two things  The instructions, DNA.  The amount of available materials.

Cell division The point at which the internal exceeds the external = division. Parent Daughter 1 Daughter 2

Rate of growth In ideal conditions, E- coli can double its volume in just 30 minutes. In one day a single bacteria could produce a 14 Kg mass.

In three days the mass of the bacteria would equal that of the…

Disorderly growth Cancer: a disorder in which cells have lost the ability to control their rate of growth. P D1 D2 D3 D2 D3 D1 D2 D3 D2 D3

Cell Division There are two main stages to division of Eukaryotic cells.  Mitosis  Cytokinesis

Mitosis The nucleus of the parent cell is divided into 2.  Each with the same number and type of chromosomes.

Cytokinesis The cytoplasm of the parent cell divides. Two distinct cells are formed.  Daughter cells

Chromosomes Highly organized segments of genetic information. Made up of chromatin.

Chromatin A specific combination of DNA and proteins.

Chromatids Each chromosome has two identical parts, chromatids.  Joined by a centromere.

The two identical parts allow for the production of two identical cells.

The process of cell growth and division is a cycle. Mitosis Cytokinesis Interphase

Mitosis Cytokinesis Interphase

The period between cell divisions 3 phases  G1, S, and G2

1.G1: Cell growth 2.S: DNA replication 3.G2: Preparation for mitosis

Mitosis (4 phases) 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase

Prophase(fig 8-12) Longest phase Centrioles take positions at opposite ends of the cell

Spindle fibers form between the centrioles Chromosomes attach to the spindle

The nucleolus disappears The nuclear envelope breaks down.

Metaphase(fig 8-14) Shortest phase Chromosomes line up along the center of the cell.

Anaphase (fig 8-15) Centromeres split Individual chromatids are pulled to opposite ends of the cell.

Telophase (fig 8-16) Final phase Chromatids uncoil to reveal a mass of chromatin.

Nuclear envelopes reform around the chromatin A nucleolus becomes visible for each daughter cell

Cytokinesis Animal Cells  The cell membrane moves inward pinching the cytoplasm into two cells.

 Each half contains a nucleus  And all necessary organelles Plant Cells  A cell plate forms dividing the cell in half

 The cell plate evolves into a new cell wall for each cell.

Scientific Notation M X 10 n A.1.) 1.0 X cm A.2.) 1.0 X cm B.1.) cm B.2.) 1,000,000 times greater