Cell Membrane Flashcards
What is the function of the cell membrane?
To protect the interior of the cell by being semipermeable and to recognise other cells using sensors in outer layer.
What is the cell membrane made up of?
Phospholipids and proteins
What are the key parts of phospholipids?
Hydrophilic head and hydrophobic tail
What are the chemical parts of a phospholipid?
Fatty acid tail and phosphate head
What is a bilayer?
Two layers of phospholipids, tails face inwards and heads face outwards, towards water-based fluid
What is a structural protein?
Give cell support and shape
What is a receptor protein?
Helps cells communicate with external environment
What are transport proteins?
Transport molecules across cell membranes (such as globular proteins)
What are glycoproteins?
Have a carbohydrate chain attached, help with cell communications and molecules transport across membrane
Practice naming the proteins of cell membrane on diagram
On back of sheet
What is the fluid mosaic model?
Proteins are embedded in bilayer, making it look like a mosaic. The plasma membrane allows these proteins to move across, like fluid.
What does selectively permeable mean?
Some substances can move into the cell easily, some cannot. It allows the cell to be protected from its surroundings.
What is the concentration gradient?
Process of particles moving through are solution from an area of higher no of particles to area with low no of particles. Aims to reach an equilibrium.
What is up the concentration gradient?
Going to an area with higher number of particles
What is down the concentration gradient?
Going to an area with a lower number of particles
What occurs with movement in and out of the cell?
Cell needs constant supply of oxygen and glucose, urea and carbon dioxide are removed. Levels of these substance must be maintained.
What is passive transport?
Movement of substances across the cell membrane down the concentration gradient (does NOT require ATP)
What are some types of passive transport?
Diffusion (gases)
Facilitated diffusion (via transport protein)
Osmosis (water molecules)
What is simple diffusion?
Where molecules move freely across membrane with no assistance (small or non polar molecules)
What is diffusion?
Driven by random movements of molecules in solution. If concentration is greater outside than inside, more molecules will randomly enter the cell to have balance
What is facilitated difussion?
Form of passive transport, transport protein helps the molecule (big or not lipid soluble) in or out of cell
What is osmosis?
Diffusion of water across a membrane to balance concentration on either side (water moves from high water concentration to area of low concentration)
What is hypertonic?
Water moves out cell (high solute in solution)
What is isotonic?
Into and out of cell (equal amounts of solute)
What is hypotonic?
Into the cell (lower solute in solution)
What is active transport?
Energy-requiring process for moving material across a cell membrane
When do we use active transport?
When particle is going from low to high concentration
When particles need help entering membrane are they are impermeable
When large particles enter the cell
What is an antiport?
Pumps molecules in both directions
What is a synport?
Pumps molecules in one direction?
What is endocytosis?
Active transport for into the cell
What is exocytosis?
Active transport for out of the cell
What are two types of endocytosis?
Phagocytosis (food-bacteria)
Pinocytosis (liquid-fat droplets)
Who organises exocytosis and endocystosis?
Golgi body or ER
