Topic 4- Cell Transport Mechanisms Flashcards
What is passive transport?
Is transport that takes place as a result of concentration, pressure or electrochemical gradients and involves no energy from a cell.
What is active transport?
Is the movement of substances into and out of our cells using ATP produced during cellular respiration
What is diffusion?
Is the movement of particles in a liquid or gas down a concentration gradient from an area of high concentration to an area of low concentration.
What is facilitated diffusion?
Is diffusion that takes place through carrier proteins or protein channels
What is osmosis?
Is a specialised form of diffusion that involves the movement of water down a concentration gradient.
Endocytosis?
Movement of large molecules into cells through vesicles formation
Exocytosis?
Is the movement of large molecules out of cells by the fusing of a vesicles containing the molecules with the cell surface membrane. Requires ATP
What is the phospholipid bilayer made up of?
Polar lipids
What are the characteristics of phospholipids?
Hydrophobic tails
Hydrophilic head
What are the functions of integral protein in the phospholipid bilayer?
Some proteins form pores or gated channels, some permanent and some temporary. They can open and close depending on what the cell needs.
What are glycoproteins and what is their function on the bilayer?
They act as antigens important for cell recognition or as receptors for hormones.
What is facilitated diffusion?
It occurs with substances with a strong negative or positive charge and larger molecules which cannot pass through the bilayer.
It involves carrier proteins which only let a certain substance through.
The protein carrier picks up a molecule from an area of high concentration then changes shape to release the molecule into the area of low concentration passively.
This process only works when the concentration gradient is in the right direction
What does osmotic concentration mean?
The osmotic concentration of a solution concerns only those solutes that have an osmotic affect. Therefore large insoluble molecules which have no effect on the movement of water are not considered
Isotonic?
The osmotic concentration of the solutes in the solution is the same as that in the cells
Hypotonic?
The osmotic concentration of solutes in the concentration of solutes is lower than that in the cytoplasm of the cells.
Hypertonic?
The osmotic concentration of solutes in the solution is higher than that in the cytoplasm.
Describe pressure potential in plant cells
In plant cells the water is mostly hypotonic to the cells water will enter the cells.
Due to the cell wall the cell doesn’t pop like it does in animals.
As the cytoplasm cells and presses on the cell wall it generates hydrostatic pressures.
The inward pressure increases until it cancels out the tendency for water molecules to move in.
The inward pressure is pressure potential.
What does it mean for a cell to be turgor?
When the osmotic force moving water into the plant cell is balanced by the pressure potential forcing it out, the plant cell is rigid, most plant cells are turgid all the time.
What is incipient plasmolysis?
If plant cells are put in a slightly hypertonic solution water moves out of the and the cell membrane pulls away from the cell wall. The protoplasm will shrink away and the acutely will change but the actual size and shape of the cell doesn’t change that much it is just the internals that change.
What is water potential? (trident)
The measure of water to move out of a cell, pure water had a water potential of 0. It has the highest water potential because it will always move to an area of lower concentration.
All other liquids will have a lower water potential (negative numbers)
What is turgor pressure?
As water enters the cell via osmosis it causes the protoplasm of the cell to expand but the cell wall stops it from expanding. Hydrostatic forces push against the cell wall, the cell wall pushes back on the protoplasm with turgor pressure. Turgor pressure will rise until both turgor pressure and osmotic potential are in equilibrium.
What is osmotic potential?
It is the potential that water has to move across the partially permeable membrane depending on condpcentration. This takes into account hyper, iso and hypotonic potentials.
What is the formula for water potential of a plant cell?
Turgor pressure + osmotic potential
What is the formula for water potential in an animal cell?
Osmotic potential
