Chapter  10  Section  10.1

Cell Growth, Division, and Reproduction

Limits  to  Cell  Size DNA Overload •  As the cell grows, the

DNA does not so there becomes an “information crisis”. o  There is a greater demand

on the “genetic library”.

Limits  to  Cell  Size Exchanging Materials •  As the cell increases in size It becomes very difficult to get

food, water, oxygen to all parts of the cell and difficult to remove waste.

•  This rate of exchange depends entirely on the “surface area” and “volume” of the cell.

Surface  Area  to  Volume  Ratio  in  cells

Division  of  the  cell •  Before the cell becomes too

large, it will divide to INCREASE the surface are/volume ratio. o  This will make the cell MORE

efficient as the exchange of materials (food, water, oxygen, waste)

o  Each cell will get a COMPLETE copy of the genetic material (DNA).

Comparing  Asexual  and  Sexual  Reproduction

Asexual Reproduction •  The production of genetically identical offspring

from a single parent. One cell divides into two. •  Occurs in many single celled organisms. (bacteria &

protozoans) •  Some multicellular organisms, like Hydra, will

produce a “bud” which is also a form of this type of reproduction.

•  Allows the organism to reproduce quickly, but can be a disadvantage if environmental conditions change because genetically identical individuals CAN’T adapt quickly.

Comparing  Asexual  and  Sexual  Reproduction

Sexual Reproduction •  Fusion of two separate parent cells called

“reproductive cells – sperm/egg”. •  The offspring inherit some characteristics

from each parent. •  Most animals/plants reproduce in this way. •  Allows genetic diversity, so some

individuals may survive if environmental conditions change.