10.1 Cell Growth

• Living things grow because it produces more and more cells.

• Are the cells of an adult larger than the cells of a baby?

NO!!! Adults just have more cells than babies do.

Limits to Cell Growth

• Volume increases faster than surface area

• The larger a cell becomes, there are more demands put on that cell. “DNA overload.”– Nutrients and waste have a hard time going in

and out of the cell.

Hammond population and highways

Ratio of Volume to Surface Area

Surface area= (length x width x 6) cm2

Volume= (length x width x height) cm3 Ratio of volume S.A. to Volume= SA/ Volume

What happens when a cells gets too large?

• Cell division- process whereby the cells divide into two daughter cells

• Before the cell divides all the DNA is copied.

• Each new daughter cells gets its own “genetic library” they each get all the DNA.

10.2 Cell Division

• Process in which the cell divides into two daughter cells. Each has the same exact information as the original cell. – Before cell division occurs the cell must

replicate or copy all its DNA.– Solves the problem of DNA overload by

dividing (reduces the cell’s volume)– Allows efficient exchange of materials with

the environment.

Chromosomes

• Structures found in the nucleus of a cell that contain genetic information.

• Human cells have 46 chromosomes

• 23 chromosomes from mom

• 23 chromosomes from dad

Make up of a chromosome

• A chromosome is composed of two identical chromatids attached by a centromere. Each chromatid is made up of tightly wound DNA wrapped around histones.

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Chromosomes

• DNA coils around a special protein called a HISTONE.

• DNA and HISTONE make

up NUCLEOSOMES.

Cell Cycle

• A cell grows, prepares for division, and divides to form two daughter cells…each of which repeat the cycle again.

• From One mitosis to the next mitosis

• Interphase, Cell division (mitosis), cytokinesis

Interphase

• G1=cell growth

• S phase= DNA is replicated

• G2=cell prepares for mitosis

• Kind of like intermission…can’t really see this happening, but happens behind the scene.

Interphase

Mitosis

• Process in which the nucleus of a cell divides.• Divided into four phases

– Prophase-1st, longest phase. Chromatin condenses and chromosomes become visible.

– Metaphase-2nd phase (shortest) chromosomes line up at center of cell

– Anaphase-3rd phase chromatids split and separate to opposite poles

– Telophase-4th phase. Almost two new cells, but not completely separated.

Mitosis

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

• The cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes.

Fine TUNING what you’ve learned.

• http://www.youtube.com/watch?v=ODwt6OdN-8Y

10.3 Regulating the Cell Cycle

• Cyclin Protein Regulators- regulate the timing of the cell cycle.– Internal Regulators- make sure that mitosis

has waited for chromosomes to replicate all the DNA.

– External Regulators- speed up or slow down mitosis.

Cancer

• Uncontrolled cell growth is called cancer

• Most healthy cells will stop dividing when they come into contact with one another.

• Cancer cells do not stop when touch another cell. Grows until the nutrient supply is gone.

Cancer

What do cells do incase of injury?

• Cells rush to the cite of the wound and rapidly divide.

• They start to slow down when they get close to each other.

• When do they stop?– When they touch one another…– At this time…you most likely have a scab.

On that note…we are done with this chapter.