Plasma Membrane Flashcards
Elements in lipids
CHO
Elements in phospholipids
CHOP
Characteristics of lipids
non-polar, insoluble in water (hydrophobic), poor conductors of heat, good insulators
Components of a triglyceride
1 x glycerol, 3 x fatty acids
Bond formed between glycerol and fatty acids
ester
Function of lipids
Energy source
Protection of vital organs
To prevent evaporation in plants
To insulate the body
They form the myelin sheath around neurones
As a water source (respiration produces metabolic water)
Components of phospholipid
Hydrophilic polar phosphate head
Glycerol
Hydrophobic non-polar fatty acid tail
Components of the plasma membrane
Phospholipid bilayer
Protein channels
Protein pumps
Glycoproteins
Glycolipids
Cholesterol
Arrangement of phospholipid bilayer
hydrophilic phosphate heads are facing the environments with water (e.g., cytosol) whereas the hydrophobic fatty acid tails are facing each other and away from the environments containing water
Function of cholesterol in plasma membrane
provides stability and flexibility to the membrane
Function of the plasma membrane
Regulates the inputs and outputs of a cell
Function of glycoproteins and glycolipids
cell communication and recognition
Diffusion
Diffusion is the net movement of particles from a high concentration to a low concentration, down a concentration gradient.
Is diffusion active or passive?
Passive (no ATP required)
Substances that use simple diffusion
Small, non-polar molecules like O2 and CO2 (exception: water)
Hydrophobic, non-polar molecules e.g., steroid hormones
Facilitated diffusion
Facilitated diffusion is the net movement of particles from a high concentration, to a low concentration, down a concentration gradient, through a protein channel.
Is facilitated diffusion active or passive?
Passive (no ATP required)
Substances that use faciilitated diffusion
Large, polar and hydrophilic substances that can’t cross directly through the phospholipid bilayer
E.g., glucose, charged ions (chloride ion, sodium ion)
Similarities between diffusion and facilitated diffusion
similarities between diffusion and facilitated diffusion?
They are both passive processes
They both move substances down a concentration gradient (high to low)
Differences between diffusion and facilitated diffusion
Diffusion is movement through the phospholipid bilayer whereas facilitated diffusion is movement through a protein channel.
Diffusion is the movement of small, non-polar, hydrophobic molecules whereas facilitated diffusion is the movement of large, polar, hydrophilic substances
Factors that affect diffusion
Concentration gradient
Distance / thickness of membrane
Surface area to volume ratio
Temperature
How concentration gradient affects rate of diffusion
If the difference in concentration on either side of the membrane is greater, diffusion will occur faster.
How distance / thickness of plasma membrane affects rate of diffusion
If the semi-permeable membrane is thinner, diffusion will occur faster.
How surface area to volume ratio affects rate of diffusion
A larger surface area to volume ratio means more particles can move across the membrane at the same time.
How temperature of plasma membrane affects rate of diffusion
Particles with greater kinetic energy will diffuse faster.
The membrane permeability increases as the temperature increases. This means that diffusion will take place more quickly when the membrane becomes more permeable
Independent variable
The independent variable is a factor that is changed or manipulated in an experiment to determine its effect on the dependent variable.
Dependent variable
The dependent variable is measured to determine if the change or manipulation of the independent variable had any effect.
Controlled variable
A controlled variable is one that is kept constant throughout the experiment.
Osmosis
Net movement of water molecules from a high-water concentration, through a partially permeable membrane, to a low water- concentration, down a concentration gradient.
Is osmosis active or passive?
Passive
Hypotonic
a solution that is lower in solute and higher in water molecules than the solution being compared to
Hypertonic
a solution that is higher in solute and lower in water molecules than the solution being compared to
Isotonic
two solutions are of equal solute concentration.
There will be no net movement of water
Animal cell in hypertonic environment
crenated
Animal cell in hypotonic solution
lysed
Plant cell in hypertonic environment
plasmolysed
Plant cell in hypotonic envrionment
turgid
Osmosis scaffold
OSMOSIS has occurred. This means that
Water has moved FROM the hypotonic ______
THROUGH the partially permeable membrane of _____
TO the hypertonic _______
______ has become crenated / lysed / plasmolysed / turgid
Active transport
The net movement of particles from a low concentration to a high concentration, against a concentration gradient, through a protein pump which requires ATP.
Is bulk transport an active or passive process?
Active (requires ATP)
Endocytosis
the bulk movement of large substances into a cell
Phagocytosis vs pinocytosis
Both forms of endocytosis. If the substance being engulfed is a solid, it is called phagocytosis. If the substance being engulfed is a liquid, it is called pinocytosis
Steps in phagocytosis if a cell is obtaining nutrients
Phagocytosis this means that
A cell engulfs a solid forming a food vacuole
Food vacuole fuses with lysosome
Solids are destroyed by digestive enzymes in lysosome
Steps in phagocytosis if a cell is destroying pathogens
Phagocytosis this means that
A white blood cell engulfs a pathogen forming a phagosome
Phagosome fuses with lysosome forming a phagolysosome
Pathogen is destroyed by digestive enzymes in lysosome
Exocytosis
bulk movement of large substances out of a cell
