Chapter 4 Passive Transport Active Transport Cell Membrane

Chapter 4 Passive Transport & Active Transport

Cell Membrane Review: • Selectively Permeable Membrane- the cell membrane only allows specific substances to pass through it

Passive Transport • Passive transport moves substances from higher concentration to lower concentration • Passive transport does not require any energy (ATP)

Concentration Gradient • A concentration gradient is a range in concentration across a space • Concentrations change from high low

Equilibrium • Equilibrium is a condition when the concentration of a substance is equal in all areas

Equilibrium

Diffusion • Diffusion is the movement of molecules from areas of higher concentration to areas of lower concentration by random movement of the molecules Lower Concentration Higher Concentration

Osmosis • Osmosis is the diffusion of water(H 2 O) through a selectively permeable membrane • Water moves to areas with less pure water and more dissolved solutes(like salt or sugar)

Solutions(review) • Solute- the substance that gets dissolved – Ex: salt, sugar, kool-aid, chocolate milk mix • Solvent- the substance that dissolves another substance – Ex: water, alcohol, milk

Types of Solutions • Hypertonic Solutions- water diffuses out of the cell – A higher concentration of solute outside of the cell draws water out of the cell – Cells will shrivel and shrink in a hypertonic solution

Types of Solutions • Hypotonic Solutions- water diffuses into the cell – A lower concentration of solute outside the cell causes water to enter the cell – The cells will expand or even burst

Types of Solutions • Isotonic Solutions- equal movement of water into and out of the cell – Equal concentration inside and outside the cell – Cells remain their normal size and shape

Transport Proteins • Proteins stuck in the cell membrane act as transport tunnels that move substances into and out of the cell

Ion Channels • Ion channels are transport proteins that move positive(+) and negative(-) ions across the cell membrane – Ex: Na+ and Cl-

Gated Ion Channels • Gated Channels can open and close to allow or prevent ions from passing through

Facilitated Diffusion • Facilitated diffusion uses carrier proteins to move substances across the cell membrane

Carrier Proteins • How Carrier Proteins Work: – 1) Bind to a substance – 2) Change shape – 3) Release substance on other side of cell membrane

Active Transport! • Active transport moves substances across the cell membrane against the concentration gradient, from low high • Active transport requires energy(ATP)

Sodium-Potassium Pump • Transports sodium ions(Na+) out of the cell and transports potassium ions(K+) into the cell • Requires ATP(energy) as a form of active transport

Movement in Vesicles • Cells use vesicles to transport large molecules into and out of the cell – Ex: glucose in & wastes out

Endocytosis • The movement of large molecules into the cell • The cell engulfs the molecule

Endocytosis

Exocytosis • Movement of large molecules out of the cell • Cell releases the substance(waste)

Exocytosis

Endocytosis & Exocytosis

END OF CHAPTER 4 NOTES!!!