cell membrane transport

What is the function of the cell membrane?

the cell membrane regulates the movement of substances in and out of the cell, maintaining homeostasis

What are the two main types of membrane transport?

passive transport:

• does not require ATP

• driven by concentration gradient high to low

active transport:

• requires ATP

• goes against concentration gradient low to high

what is simple diffusion?

Diffusion is the movement of molecules from an area of high concentration to an area of low concentration until equilibrium is reached. This process does not require energy (passive transport).

What is facilitated diffusion?

Facilitated diffusion is a type of passive transport where molecules move through the cell membrane with the help of transport proteins (e.g., channel or carrier proteins), without the use of energy.

• it requires transmembrane proteins

• it is for small water-soluble solutions.

What is osmosis?

Osmosis is the passive movement of water molecules through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

• driven by concentration gradient

• wherever salt goes, water follows

• higher concentration of water inside(intracellular)

• low concentration of water means there is a GREATER SOLUTE (salt/sugar) concentration

What is active transport?

Active transport is the movement of molecules across the cell membrane against their concentration gradient, requiring energy (usually in the form of ATP). Examples include the sodium-potassium pump.

• strict on what comes in and out

• low concentration to high

What is the sodium-potassium pump?

The sodium-potassium pump is a type of active transport that moves 3 sodium ions out of the cell and 2 potassium ions into the cell, against their concentration gradients, using ATP energy. This helps maintain the cell’s resting membrane potential.

What is endocytosis?

Endocytosis is the process where the cell membrane engulfs extracellular material, bringing it into the cell. This includes processes like phagocytosis (cell eating) and pinocytosis (cell drinking).

What is exocytosis?

Exocytosis is the process by which cells expel materials from the inside to the outside by vesicle fusion with the cell membrane, commonly seen in the secretion of hormones and neurotransmitters.

What are the different types of transport proteins in cell membranes?

• Channel Proteins – Provide a pathway for ions or molecules to pass through the membrane.

• Carrier Proteins – Bind and transport molecules across the membrane by changing shape.

• Pumps – Use energy (ATP) to actively transport substances against their concentration gradient.

What is the difference between primary and secondary active transport?

• Primary Active Transport: Direct use of energy (ATP) to transport molecules against their concentration gradient (e.g., sodium-potassium pump).

• Secondary Active Transport: Indirect use of energy, using the electrochemical gradient created by primary active transport to drive the movement of other molecules (e.g., sodium-glucose co-transport).

  • purely driven by concentration gradient

What is the electrochemical gradient?

The electrochemical gradient refers to the combined difference in both concentration and electrical charge across the cell membrane that drives the movement of ions.