Chapter 4Section 1

Exchange within the Environment

A cell must be able to take in energy and get rid of wastes

The exchange of materials between a cell and its environment takes place at the cell membrane

Exchange with the Environment

Movement of particles from an area of high concentration to low concentration

Naturally spreading out

Diffusion

Can occur across cell membranes or outside the cell

No energy is needed

Diffusion

Tea in cup of hot waterFragrance from a candle

Examples

Diffusion Demonstrations

The diffusion of water through the cell membrane

Pure water has the highest concentration (100%)

To lower concentration, something must be added to the water

Osmosis

Diffusion is anything, Osmosis is water

In diffusion or osmosis, particles move from areas of _High__ concentration to areas of _Low_ concentration.

Summarize the difference between diffusion and osmosis.

Salt water has a low concentration of water and high concentration of salt.

The cells of your body have high concentration of water and low salt.

Which way will the water move?

Thirsty for sea water?

Water from your cells will move from high to low concentration, leaving your cells and dehydrating you

Occurs through the proteins embedded throughout the membrane

No energy usedStill moving high to lowIncludes sugars and amino acids

Passive Transport

Occurs through the proteins embedded throughout the membrane

Uses energy (ATP)Occurs from LOW to HIGHExample – nutrients brought into the roots of a plant

Active Transport

Bringing large particles into the cell

Means “within the cell”The cell membrane surrounds a particle and encloses it in a vesicle

Endocytosis

Taking things out of the cellMeans “outside the cell”Vesicles are formed at the ER or Golgi and brought to the membrane to be released out of the cell

Exocytosis

Nearly all of the energy that fuels life comes from the sun

Cell Energy

The process by which plants capture light energy from the sun and convert it into sugar

6CO2 + 6H2O + light energy C6H12O6 + 6O2

Photosynthesis

Molecules in plant cells that absorb light energy

Chlorophyll is the main pigment for photosynthesis

Pigments

Cellular respirationFermentation

2 ways to release stored energy from food molecules

The process of releasing ATP in the cell from oxygen and glucose: producing carbon dioxide and water

Cellular respiration

The breakdown of sugars to make ATP in the absence of oxygen

Fermentation

Cellular respiration takes place in the mitochondria

C6H12O6 + 6O2 6CO2 + 6H2O + energy

Relates to breathing in that both use oxygen and release carbon dioxide

Like the lungs but not quite

In the muscles, producing lactic acid as a product

In bacteria and yeast, used in baking bread. The CO2 produced makes bread light and fluffy

2 types of fermentation