Biology Outline

Biology Outline

  • Submitted By: blahblah82
  • Date Submitted: 01/15/2009 7:29 PM
  • Category: Science
  • Words: 1186
  • Page: 5
  • Views: 365


o Found in many organisms, including plants, algae, fungi, and nearly all prokaryotes. Animal cells do not contain cell walls.
o Lies outside the cell membrane. Most cell walls allow water, oxygen, carbon dioxide and other substances to pass through.
o The main function of the cell wall is to provide support and protection for the cell.
o Made from fibers of carbohydrate [CELLULOSE-carbohydrate fiber] and protein. The cell produces these substances, which are then released at the surface of the cell membrane and assembled to form the wall.

o Identified by Robert Brown [1831]
o The nucleus controls most cell processes and contains the hereditary information of DNA.
o All eukaryotic cells, including the plant and animal cells, contain a nucleus.
o Contains all the cell’s DNA [holds the coded instructions for making proteins and other important molecules.
o The nucleus is important because making proteins is one the main functions of cells.

Chromatin and Chromosomes
o Chromatin: The granular material visible with in the nucleus, it consists of DNA bound to protein. Most of the time it is spread through out the nucleus.
o Chromosomes: When a cell divides, chromatin condenses to form chromosomes. They are distinct, threadlike structures containing the genetic information that is passes from one generation of cells to the next.

o Nucleolus: Most nuclei also contain a small dense region known as the nucleolus. This is where the assembly of ribosomes begins, ribosomes aid in the production of proteins within the cell.

Nuclear Envelope
o Nuclear envelope: A double-membrane layer that surrounds the nucleus. The nuclear envelope is dotted with thousands of nuclear pores, which allow material to move into and out of the nucleus. The nucleus sends a steady stream to the rest of the ell through the nuclear pores.

o Cytoskeleton: helps to support the cell. The...

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