Chapter 3 Structure of Plasma Membrane Flashcards
Why must cell allow substances to move in and out?
Maintain living processes
What does a phospholipid molecule consist of?
Polar head ( hydrophilic )
Nonpolar tail (hydrophobic)
What are the function of glycoprotein and glycolipids
act as receptors to hormones, stabilize the membrane by forming hydrogen bonds with water and act as antigens for cell identification
Why can cholesterol be found in the phospholipid bilayer?
Make it stronger, flexible and less permeable to water-soluble substance
What factors determine whether a molecule can pass through a plasma membrane?
Molecule size, polar molecule and ionic charge
Examples of polar and non polar molecules
Polar
-Water
-Methanol
Nonpolar
-Oxygen
-Carbon dioxide
What is passive transport?
Process that does not use energy
Examples of passive transport
Simple diffusion
Osmosis
facilitated diffusion
What is simple diffusion?
Movement of molecules or ions from an area of high concentration to an area of low concentration
The moving molecules are said to move down the concentration gradient until a dynamic equilibrium is achieved
What is osmosis
Movement of water molecules from an area of high water potential to an area of low water potential randomly through a selectively permeable membrane
This membrane is permeable to water but impermeable to some solutes ( sucrose molecules )
What is facilitated diffusion?
When lipid-insoluble molecules such as ion, large molecules ( amino acids or glucose ) are unable to pass through the phospholipid bilayer move across the membrane with the aid of transport proteins
Does not use energy because transport proteins transport molecules down a concentration gradient
What are the function of channel proteins?
Form channels or canals to allow small sized solutes and ions to diffuse across the plasma membrane
- It has specific internal characteristics that only allow specific ions to pass through it
What are the function of carrier protein
Have specific sites that can only bind to a specific molecule
What is active transport?
Movement of SUBSTANCES across a plasma membrane
What are the characteristics of active transport? ( 3m )
Movement of molecules or ions occurs against the concentration gradient
Requires energy from ATP molecules
Requires specific carrier proteins which possess receptors to bind to the ATP molecules
What is the result of active transport?
Accumulation and excretion of molecules or ions in the cell
What are carrier proteins involved in active transport known as?
Pumps
ie; carrier proteins that transport sodium ions to extracellular and potassium ions into the cell are called sodium-potassium pump
Where can proton pumps be found?
Epithelial cells lining the stomach cavity
What are the functions of the proton pump?
( 4m )
Causes the acidity of the stomach contents
Enable hydrogen ion to be transported by the carrier proteins
Accumulation of the hydrogen ion
Acid production in the stomach cavity
