Understanding Enzymes, Diffusion, and Osmosis in Biology

Enzymes are biological catalysts that speed up chemical reactions.

Without enzymes, reactions would be too slow for life to exist.

Reactions happen at lower temperatures.

Catalyst: a substance that increases the rate of chemical reactions.

Carbohydrase: enzymes which catalyze the breakdown of carbohydrates.

Lipase - pancreas, protease - colon, amylase - salivary glands.

All enzymes are proteins. Enzymes are made inactive by high temperatures. Enzymes work best at a particular temperature.

Describing: an enzyme looks like a lock, the substrate must be a perfect fit, the enzyme changes the substrate into new molecules called products.

Process of digestion: inside the alimentary canal, large molecules are broken down into smaller ones.

pH: measures the acidity of different elements' particles. They are denatured. Active site no longer fits the substrate. pH 7 is neutral.

Diffusion: the movement of molecules from an area of high concentration to an area of low concentration.

Solid - cannot move very far

Liquid - can move more freely

Gas - freer still

Plants need carbon dioxide for photosynthesis. A lower concentration of carbon dioxide inside the leaf, a higher concentration outside the leaf.

Oxygen, a waste product of photosynthesis, higher concentration inside the leaf, lower outside.

All organisms need O2, also they produce CO2 by respiration.

Diffusion plants - root hair cells, osmosis, water.

- The cell membrane is where molecules enter and leave the cell.

- Cells need oxygen for respiration.

- The higher the temperature, the greater the rate of diffusion. The particles have more kinetic energy.

OSMOSIS: the net movement of water across a semi-permeable membrane from high concentration to low.

Dilute sugar solution + concentrated sugar = partially permeable membrane

Cytoplasm: a solution of proteins and other substances in water.

Osmosis and animals: the cytoplasm inside the cell is a fairly concentrated solution. The proteins and many other substances dissolved in it are too large to get through the cell membrane. Water molecules, though, can get through.

Osmosis and plants: plant cells do not burst in pure water. Water diffuses into the cytoplasm and vacuole through the partially permeable cell surface membrane.

ACTIVE TRANSPORT: movement of molecules and ions in or out of cells through the cell membrane against a concentration gradient, using energy from respiration.

Plants - Absorption of ions into root hair cells (nitrate ions)

Animals - Absorption of small amounts of sugar into villi.

The particles can move up the concentration gradient if energy is used.

Particles move against. Does require energy from respiration.

Describing: The glucose molecule enters the transport protein. The transport protein changes shape. The energy needed for it to do this is provided by respiration in the cell. The change of shape of the transport protein pushes the glucose molecule into the cell.

Diffusion - O2/CO2, osmosis - H2O, active transport - energy against concentration gradient.