Matthew Mekari

Honors Biology per.7

11/14/04

Ch. 4 Outline

  1. The Cell Theory

A. Cells, themselves alive, are the basic living unit of organization of all organisms are the basic unit of life.

B. Cells arise from other cells.

C. All organisms are composed of more than one cell.

  1. Three Common Features of A Cell
  2. A boundary that separates the inside of the cell from the rest of the world
  3. A set of genes.
  4. A cell body
  1. Parts of the cell
  2. Nucleus- In eukaryotic cells, the membrane-enclosed structure that contains most of a cell’s genetic information in the form of DNA. The nucleus is the library of the cell. The nucleus houses all the information needed for a cell to produce proteins.
  3. Nucleoid- In the prokaryotes, the restricted part of the cell that contains the cell’s DNA; it is not surrounded by a membrane.
  4. Cytoplasm- The part of the cell outside the nucleus but inside the membrane.
  5. Cytosol-The part of the cytoplasm not contained within membrane-enclosed organelles. Most of the cell’s biochemical work occurs within the cytosol.
  6. Endoplasmic reticulum- An elaborate structure needed for cell reproduction, since it is important in the synthesis of proteins and lipids, which the cell exports. One part of the endoplasmic reticulum- the rough endoplasmic reticulum-is studded with ribosomes and makes proteins mainly destined for export to the outside or the outer surface of the cell. Another part of the endoplasmic reticulum- the smooth endoplasmic reticulum- contains no ribosomes and appears to function in the synthesis of lipids.
  7. Organelles- A subcellular structure that performs a specialized task; in eukaryotic cells, many organelles are enclosed by membranes, which isolate the contents or the organelle from the rest of the cytoplasm.
  1. Cellular membranes
  2. Four major roles of cellular membranes:
  3. Membranes are essential boundaries that separate the inside from the outside.
  4. Membranes regulate the contents of the spaces they enclose.
  5. Membranes seve as the “workbench” for a variety of biochemical reactions, especially those involving the metabolism of lipids and the secretion of proteins.
  6. Membranes participate intimately in energy conversions.
  7. The Fluid Mosaic Model
  8. The basic structure of the membrane is a liquid bilayer, with two sheets of phospholipids arranged tail to tail.
  9. Proteins are dispersed through the membrane like the individual pieces of stone or tile in a mosaic. Proteins contribute to ,membrane structure and function. Some proteins span the membrane, while others are confined to the inner and outer surfaces.
  10. The membrane is fluid; both protein and lipid molecules move freely within the plane of the membrane.
  11. The liquid bilayer serves as a hydrophobic barrier, confining hydrophilic molecules to the inside or the outside of a cell (or organelle).
  12. Some membrane proteins help transport specific molecules across the membrane.
  1. Diffusion
  2. Simple diffusion- The random movement of like molecules or ions from an area of high concentration to an area of low concentration.
  3. Concentration gradient- The presence of an area of high concentration adjacent to an area of low concentration.
  1. Osmosis
  2. Osmosis is the movement of water across any selectively permeable membrane in response to a concentration gradient.
  3. A hypotonic solution has a total concentration of solutes lower that that within a cell.
  4. A hyertonic solution has a total concentration of solutes higher than that within a cell.
  5. An isotonic solution has a total concentration of solutes that is the same as the cell’s interior.