2.4-Transport through membranes

Define Diffusion

The movement of particles from an area of low concentration to high concentration

Properties of substances that can diffuse across the phospholipid bilayer

Small and uncharged

3 examples of substances that can diffuse across the phospholipid bilayer

Oxygen

Carbon Dioxide

Ethanol

Define facilitated diffusion

The movement of particles from an area of high to low concentration with the help of integral proteins

Describe the process of facilitated diffusion

Charged molecules attach themselves to the integral protein and are transported across the membrane

Properties of substances that use facilitated diffusion

large and charged

3 substances that use facilitated diffusion

Chloride ions

glucose

Sodium ions

Define active transport

Movement of substances across a partially permeable membrane from an area of low concentration to high concentration

Describe the process of active transport

Charged molecules attach themselves to the integral protein and are transported across the membrane using energy to move across the concentration gradient

Properties of substances that use active transport

Charged and against the concentration gradient

3 substances that use active transport

sodium and chloride ions

mineral ions

glucose

Define endocytosis

The transportation of large substances into a cell

Define exocytosis

The transportation of large particles out of a cell

Describe the process of endocytosis

A vesicle forms on the cell membrane to engulf the substances entering the cell

Describe the process of exocytosis

A vesicle containing the substances fuses with the cell membrane allowing the substance to leave the cell

Properties of substances that use exo- or endocytosis

Large

3 substances that use endo- or exocytosis

Pathogens

Insulin

Hormones

Describe a channel protein

Protein that creates a channel for the substance to pass through, like a pore

Describe a carrier protein

Protein that has an active site for the substance to attach to that then changes shape to transport the substance across the membrane

Which forms of transport use integral proteins

Active Transport and facilitated diffusion