Cell membrane Flashcards
What are the main functions of lipids?
- Store energy
- important structural components of cell membranes
- Light absorption pigments
- Thermal insulation (plants)
What are the compounds of Triglycerides?
Glycerol & fatty acids
What is a saturated fatty acid?
A fatty acid with all bonds saturated with hydrogen bonds (relatively straight & packed closely together) (ex butter)
What is an unsaturated fatty acid?
one or more carbohydrates form double bonds (cause bends in molecule, preventing close packing) (ex oils)
Saturation determines the … & … of lipids
fluidity & melting points
Phospholipids are major components of all biological membranes. What are the Phospholipids components?
Start with a triglycerides —> one of the three fatty acids (repel water) is replaced by a phosphate group (attract water) —> creates charged molecule
What does biological membranes contain?
Lipids, proteins & carbohydrates
The fluidity is mainly affected by two factors, which?
- Lipid composition - cholesterol & long-chain, saturated fatty acids are packed tightly together (less fluidity)
- Temperature - fluidity decreases with lower temperature, many organisms replace saturated fatty acids with unsaturated ones in response to cold.
There are three general types of membrane proteins, which are they?
- Peripheral - surface of the membrane, low portion of animo acids, hydrophilic, not imbedded in bilayer.
- Anchored - anchored to membrane through covalently attached lipids
- Integral - part of protein imbedded in bilayer (hydrophobic domains)
What is a glycolipid?
carbohydrate that is covalently bonded to a lipid
(Glycoprotein - one or short carbohydrate chain covalently bonded to a protein)
(Proteoglycans - more carbohydrates attached)
Explain cell recognition
When one type of a cell specifically binds to another cell of a certain type
Explain cell adhesion
The connection between two cells is strengthened.
*two types - homotypic (most common, cell binds to same molecule) & heterotypic (cell bind to different molecule, sperm/egg, algae)
There are three types of cell junctions, which are they?
- Tight junction: prevents substances to move through the space between cells
- Desmosomes: holds neighbouring cells firmly together
- Gap junctions: channels that run between membrane pores, allows substances to pass between cells (kanal)
There’s both active and passive membrane transport - what’s the different?
The passive transport is not in need of any chemical energy to work. It is driven by the concentration gradient.
The active transport needs chemical energy to work.
What are the three different states of osmosis?
- Hypertonic - higher concentration of solution outside
of the cell —> water is loss —> cell shrinks - Isotonic - both solutions have equal solute concentration
- Hypotonic - Lower solute concentration inside of the cell —> water is gained —> cell expand (can lead to cell rupture (bursting)
There are two types of gated ion channels, which are they?
- Ligand gated channel- particular molecule (ligand) must bind to a part of the channel protein (gate will stay open as long as the ligand is bound to the channel protein)
- Voltage gated channel - Change in polar of the membrane opens the gate (at resting potential the gate is glosed)
What’s Aquaporins?
Water can cross membranes through specific protein channels
(Often ungated, usually always open)
Explain what primary active transport is
Transport requires chemical energy in the form of ATP. Needs energy as it transports a substance against its concentrations gradient (low conc. —> high conc.)
Three different types of primary active transports, which?
- Uniporter - one substance in one direction
- Symporter - two different substances in same directions
- Antiporter - two different substances in opposite direction
Explain what secondary active transport is
Transport driven by the ion concentration gradient formed by active transport
