Microscope Men Robert Hooke 1665 Antonie von Leeuwenhoek

Microscope Men Robert Hooke - 1665 Antonie von Leeuwenhoek -1675

Matthias Schleiden Theodor Schwann Rudolf Virchow

1. Living things are made up of cells. 2. The cell is the basic unit of life. 3. All cells come from pre-existing cells by division. 4. Cells contain DNA which is passed from cell to cell during cell division. 5. All cells are basically the same in chemical composition. 6. All energy flow (metabolism & biochemistry) of life occurs within cells.

Crossing the Membrane • CO 2 • Small molecules that can cross CM freely.

Diffusion • Concentration gradient – different between concentration of one molecule in one area vs. another. • Diffusion occurs down a concentration gradient.

Osmosis • In cells, osmosis is the diffusion of water across a cell membrane.

Turgor Pressure vs. Plasmolysis

Turgor Pressure vs. Plasmolysis

Turgor Pressure vs. Plasmolysis

Turgor Pressure vs. Plasmolysis

Facilitated diffusion • Passive Transport • No energy required • Occurs “down” the concentration gradient

• Diffusion & Osmosis are examples of passive transport • Facilitated diffusion makes use of carrier proteins

Active Transport • • Moving against the concentration gradient Going from low concentration to high Energy is needed to transport molecules. Involves carrier proteins

Bulk Transport • Many macromolecules are too large to be transported by carrier proteins. • They are transported in or out of the cell by means of vesicle formation

“Cell drinking”

Why are cells so small? • Volume is how much room we have – so we can fill all that space with food coming in or waste going out. • Surface area is how much room we have to move items in and out. • The bigger the cell, the more waste it produces and food it needs, but the less it can move those substances across the membrane