Chapter 3aOverview of the

cell, and structure of the plasma

membrane

http://www.youtube.com/watch?v=gFuEo2ccTPA

The cell is the basic structural and functional unit of life

Amoebas are single-cellular

Humans, dogs, trees are multi-cellular

Human body has 50 to 100 Trillion cells

200 types

First to observe cells – Robert Hooke in 1600s (1665) (he observed cork)

Anton van Leeuwenhoek observes single cell organisms in pond water 1674

1838 Matthias Schleiden concludes all plants are made up of cells

1839 Theodor Schwann concludes all animals are made up of cells

1855 Rudolph Virchow proposed all cells come from existing cells

These discoveries were very important, before ‘cell theory’ which includes all these discoveries, people accepted the theory of spontaneous generation

Four concepts that are known as the Cell Theory

1. A cell is the basic structural and functional unit of life.

2. The activity of an organism depends on the individual and collective activities of its cells

3. Principle of complementarity, (its function depends on its form)

4. Continuity of life has a cellular basis

Cubelike Tilelike Disk-shaped Spherical Branching Cylindrical

Figure 3.2

All cells are composed chiefly of carbon, hydrogen, nitrogen, oxygen, and trace amounts of several other elements

All cells have the same basic parts and some common functions

Human cells have 3 Main PartsHuman cells have 3 Main Parts

1. Plasma membrane Outer boundary of the cell

2. Cytoplasm Intracellular fluid packed with organelles

3. Nucleus Controls cellular activities

Separates intracellular fluids from extracellular fluids

Plays a dynamic role in cellular activity

Thin, Double layer (bilayer) of lipids with imbedded, dispersed proteins

Bilayer consists of phospholipids, cholesterol, and glycolipids

Phospholipids have hydrophobic and hydrophilic bipoles

Each phospholipid molecule has a polar ‘head’ that is charged and is hydrophilic

Each phospholipid molecule has a nonpolar ‘tail’ made of 2 fatty acid chains and is hydrophobic

Hydro = water Philic = loving Phobia = hating Polar heads are attracted to water

so they lie on the inner and outer surfaces of the membrane

Nonpolar tails avoid water and line up in the center of the membrane

Plasma membranes also have proteins, glycolipids, glycoproteins, and cholesterol

20% of all membrane lipid is cholesterol

Cells recognize one another by markers made out of glycoproteins called Glycocalyx

Small extensions of the plasma membrane that project from a free, or exposed cell surface

Increases surface area

Most often found on the surface of cells that function in absorption like intestinal and kidney cells

Next time!Study guide check pages 53 – 55 after

next lecture.

http://video.google.com/videoplay?docid=-7204725871954420481