Studied by 1 person
Looks like no one added any tags here yet for you.
Lipids
Fats and oils
Triglycerides
Also called neutral fats - function is long term energy storage, protection and insulation
Triglyceride structure
Glycerol molecule + 3 fatty acids
Glycerol
3 carbon alcohol with a hydroxyl group attached to each carbon
Fatty acids
Organic acids that have a COOH group joined by a hydrocarbon tail
Unsaturated gives a kink
Condensation reaction
Forms water as an oxygen atom and two hydrogen atoms are removed from the glycerol and the fatty acid
Ester bond
The bond formed when fatty acid molecules are joined to glycerol molecules in condensation reactions
Phospholipids
A lip is containing a glycerol bound to two fatty acids and a phosphate group
Phosphoric acid
H3PO4
H3PO4
Phosphoric acid
Reaction creates a ….. bond
Phosphate ester bond
Tail
hydrophobic fatty acid chain
Head
Phosphate group and glycerol molecule
Hydrophilic - water loving head
Properties of the head
Polar
Soluble
Hydrophilic
Tail properties
Non polar
Not charged
Hydrophobic
Fluid mosaic model
Proteins that are permanently embedded in the cell membrane; they facilitate transport and communication across the membrane.
Peripheral proteins
Proteins that are temporarily attached to the cell membrane and can be found on the surface, playing roles in signaling and maintaining cell structure.
is the phospholipid bilayer permeable or non permeable
Phospholipids bilayer is a selectively permeable barrier
Passive diffusion
Small, non polar molecules pass freely
Movement down a concentration gradient:
Energetically favourable (no energy needed)
Spontaneous
Net movement until equilibrium is reached
At equilibrium movement continues but equal rate in each direction e.g. oxygen, carbon dioxide
Other molecules are either too large or are polar and need help to cross- proteins imbedded in the membrane provide a route through
Facilitated diffusion
Hydrophilic molecules and ions can’t cross the bilayer easily
Need help in the form of channels (fast) or carriers (slow)
Movement still down conc gradient still energetically favourable
Spontaneous net movement until equilibrium is reached
Channels may be gated - not always open
Active transport
The movement of molecules against a concentration gradient (low to high), requiring energy (typically from ATP) to transport substances across cell membranes.
Energetically unfavourable
Reaches unbalanced equilibrium allows accumulation to occur
Two types- primary and secondary
Primary Active Transport
Type of active transport that directly uses energy, usually from ATP, to move molecules against their concentration gradient across a membrane. ATP → ADP + Pi
Secondary active transport
A type of active transport that uses the energy from the movement of one molecule down its concentration gradient to drive the movement of another molecule against its concentration gradient.
Cytosis
Movement of large complex macromolecules or even cells
Features of cytosis
molecules in vesicles
Don’t travel through the membrane itself
Three types- exocytosis, endocytosis, phagocytosis
Exocytosis
A process by which large macromolecules or cells are expelled from a cell via vesicles fusing with the cell membrane, releasing their contents outside the cell.
Endocytosis
The process by which cells engulf external materials, forming vesicles to bring substances into the cell.
Phagocytosis
A type of endocytosis in which cells engulf large particles or microorganisms, forming a vesicle that brings the material into the cell.
Osmosis
Movement of a solvent such as water through a semipermeable membrane into a solution of higher solute concentration that tends to equalise the concentrations of solute on the two sides of the membrane
Isotonic solution- animal cells
Water passes in and out at the same rate
No net movement
Hypertonic solution- animal cells
Water leaves faster than it enters
Net outflow - cell shrivels
Hypotonic- animal cells
Water enters faster than it leaves
Net inflow
Cell swells and bursts (lysis)
Isotonic solution - plant cells
Water passes in and out at the same rate
No net movement
Hypertonic- plant cells
Net outflow
Vacuole loses water
Cytoplasm shrinks and cell becomes flaccid (plasmolysis)
Hypotonic solution- plant cells
Net inflow
Vacuole fills to capacity
Cell membrane pressed on cell wall
Turgor pressure develops ( cell becomes rigid/turgid)
Measuring osmosis: water potential
Pressure is measured in kPa
High water potential = lots of free moving water molecules (pure water 0kPa)
Low water potential = less free moving water molecules
Solutes reduced water potential- negative values
Water potential in animal cells
Water potential of cell = solute potential
Plant cell water potential
Plant cell WP= solute potential + pressure potential
