10.1-Cell Growth, Division, & Reproduction Limits to Cell Size
The larger a cell becomes, the more demands the cell places on its DNA. In addition, a larger cell is less efficient in moving nutrients and waste materials across its cell membrane.
Information Overload Living cells store critical information in DNA. As a cell grows, that information is used to build the molecules needed for cell growth. As size increases, the demands on that information grow as well. If a cell were to grow without limit, an “information crisis” would occur.
Exchanging Materials Food, oxygen, and water enter a cell through the cell membrane. Waste products leave in the same way. The rate at which this exchange takes place depends on the surface area of a cell. The rate at which food and oxygen are used up and waste products are produced depends on the cell's volume. The ratio of surface area to volume is key to understanding why cells must divide as they grow.
Division of the Cell
Before a cell grows too large, it divides into two new “daughter” cells in a process called cell division. Before cell division, the cell copies all of its DNA
It then divides into two “daughter” cells. Each daughter cell receives a complete set of DNA. Cell division reduces cell volume. It also results in an increased ratio of surface area to volume, for each daughter cell.
Cell Division & Reproduction The production of genetically identical offspring from a single parent is known as asexual reproduction Offspring produced by sexual reproduction inherit some of their genetic information from each parent
Asexual Reproduction In multicellular organisms, cell division leads to growth. It also enables an organism to repair and maintain its body. In single-celled organisms, cell division is a form of reproduction. Asexual reproduction is reproduction that involves a single parent producing an offspring. The offspring produced are, in most cases, genetically identical to the single cell that produced them.
Asexual reproduction is a simple, efficient, and effective way for an organism to produce a large number of offspring Both prokaryotic and eukaryotic single-celled organisms and many multicellular organisms can reproduce asexually
Sexual Reproduction In sexual reproduction, offspring are produced by the fusion of two sex cells—one from each of two parents. These fuse into a single cell before the offspring can grow. The offspring produced inherit some genetic information from both parents. Most animals and plants, and many single-celled organisms, reproduce sexually.
