Topic 4 - Cell Physiology Flashcards
Give the 5 things that make up the Phospholipid bilayer
Cholesterol Extrinsic Proteins Intrinsic Proteins Hydrophobic tails Hydrophilic Heads
Why is the Phospholipid bilayer called the ‘Fluid Mosaic Structure’
The phospholipids in the cell membrane are constantly moving while the proteins are scattered among them
What are Polysaccharides bound either by proteins or lipids to the Cell-Surface membrane called
Glycoproteins and Glycolipids
What are som factors that influence the fluidity of the Cell-surface membrane
The more phospholipids with unsaturated hydrocarbon chains there are, the more fluid is the membrane
Phospholipids with longer hydrocarbon chains decrease the fluidity of the membrane
The membrane is more fluid at high temperatures and less fluid at low temperatures
Cholesterol provides additional binding forces at high temperature, so decreases membrane fluidity, and keeps the membrane in a fluid state at low temperature
What is the function of the Glycocalyx
It allows cells to recognise eachother and group together to form tissues
Why can glycoprotein receptors and signalling molecules fit together
They have complementary shapes
What are the factors that determine the route take across the cell-surface membrane
The size of the molecule
The polarity and non-polarity of the substance
The concentration of the substance either side of the membrane
What is Passive movement across the Cell-surface membrane
It occurs down the concentration gradient and does not require energy expenditure from ATP
What does diffusion rely on
The kinetic energy of the substances in solution
What is the definition of Diffusion
The net movement of a substance from an area of high concentration to an area of low concentration
Why is it called Facilitated Diffusion
The substances movement is facilitated by particular membrane proteins
Give 2 types of membrane proteins
Channel Proteins
Carrier Proteins
What is the structure of Channel proteins
They have a hydrophilic core through which ions and water may diffuse. These channels have a specific shape to allow one type of ions through
How do Channel proteins regulate flow
They open and close their channels
What are aquaporions
The specific water channel,proteins where most water diffuses through
What is the function of carrier proteins
They transport medium-sized molecules such as glucose and amino acids across the cell-surface membrane
How do Carrier proteins work
The molecule binds to a site on the protein, which changes the shape to bring the molecule through the membrane
What is the definition of Osmosis
The movement of water from an area of high concentration to an area of low concentration across a selectively permeable membrane
What is the definition of Osmosis in terms of water potential
The diffusion of water across a selectively permeable membrane from an area of high water potential to an area of lower water potential
What does the addition of solutes to pure water do to the Water potential of the solution
It makes it more negative
What does an increase of Pressure to pure water do to the Water potential of the solution
It makes it more positive
What is the equation for water potential
Water potential = solute potential + pressure potential
What is the Water potential of a cell
The measure of the free energy of the water molecules in a system
Why is the water potential of Pure water always 0
Because all the molecules are free, and there is no solvent to affect the water relations of the cell
How do Water molecules become not-free
They form shells around the solutes
What happens to a Cytoplasm if placed in pure water, and why
The cells in the cytoplasm will diffuse into the cytoplasm by osmosis out of the pure water, as a cytoplasm has a negative water potential, compared to Pure waters, which is 0
What happens to Red Blood cells when placed in a Hypotonic solution
They will take in the water, and swell until they burst (lyse)
How do fungi and plants prevent them from Bursting
They have rigid cell walls
What happens to Red Blood cells when placed in a Hypertonic solution
The cell will lose water by osmosis, shrink and become crenated
What is Plasmolysis
When the Cells start to lose contact with their cell walls
What is incipient Plasmolysis
The point at which the cytoplasm just begins to lose contact with the cell wall
What is the definition of Active Transport
The movement of substances across a selectively permeable membrane from an area of low concentration to an area of high concentration against the concentration gradient
How does Active transport differ from Osmosis and Diffusion
It requires energy and therefore goes against the Concentration gradient
Why are carrier proteins referred to as Pumps in Active transport
Because they used energy from ATP, to push the substances through the membrane
In Active transport, where is the energy gained from
The Mitochondria synthesises ATP
What is Cytosis
The movement of substances in and out of the cell without having to pass through the cell-surface membrane
How do Endocytosis and Exocytosis differ
Endocytosis involves the bulk transport into the cell
Exocytosis involves the bulk transport out of the cell
What happens during Endocytosis
During Endocytosis the cell-surface membrane invaginates and the membrane folds round the substance to from a vacuole or vesicle that enters the cytoplasm while the cell-surface membrane reforms
What is Phagocytosis
The uptake of solids particles into the cell within vacuoles
What is Pinocytosis
The uptake of solutes and large molecules into the cell within vesicles
What happens during Exocytosis
During Exocytosis, secretory vesicles move towards and fuse within the cell-surface membrane, releasing their protein contents out of the cell
