Lipids
What are the three main types of lipids?
Triglycerides (fats)
Phospholipids
Steroids
What is the difference between membrane fluidity and membrane permeability?
Fluidity - ability of phospholipids to move within the membrane
Permeability - the ability to let molecules/substances through
What components, other than phospholipids, make up the membrane?
Carbohydrates, cholesterol, and proteins
What gradients are involved in passive transport?
Chemical gradient - concentration differences of solutes
Electrochemical gradient - concentration differences of charges; forms potential energy of membrane
Describe active transport
Requires an input of energy (ATP)
Substances are moved against the gradient (low to high)
What are the functions of the three types of lipids?
Fats - energy storage
Phospholipids - make biological membranes
Steroids - hormones and presence in animal cell membranes as cholesterol
What factors are involved in membrane fluidity?
Temperature
Saturation
Fatty acid tail length
What are the two types of membrane proteins?
Integral proteins
Peripheral proteins
Describe passive transport.
No need for energy input (ATP)
Movement along the gradient, high to low
What are the types of active transport?
Secondary active transport
Describe the structure of the three types of lipids
Fats - glycerol head and three fatty acid tails
Phospholipid - phosphate head, glycerol backbone, and two fatty acid tails
Steroids - four aromatic rings with polar attachments
If an organism lived in an extremely hot environment, what would their biological membrane look like?
Longer fatty acid tails
Higher saturation
Describe the two types of membrane proteins.
Integral proteins - a portion of the protein is anchored to the bilayer
Peripheral proteins - bond to the polar side of phospholipdis
What are the types of passive transport?
Simple diffusion
Osmosis
Facilitated diffusion
What is primary active transport?
Moves solutes against the chemical gradient using a pump and ATP
What is the difference between saturated and unsaturated fatty acids?
Saturated - no double covalent bonds, common in animals, solid at room temperature
Unsaturated - at least one double covalent bond, common in plants, and liquid at room temperature
What are the three main factors that determine the permeability of a molecule?
Size
Polarity
Charge
What are the subtypes of integral proteins? Describe them.
Transmembrane - span the entire lipid bilayer
Lipid-anchored - uses a tail anchored in the membrane
Describe osmosis. What does it mean to be isotonic, hypertonic, and hypotonic?
Isotonic - equal amount on either side
Hypertonic - low water outside so water rushes out of the cell -> shrinkage
Hypotonic - high water outside so water rushes inside the cell -> swelling
What is secondary active transport?
Uses the energy of an existing electrochemical gradient to move a substance against its gradient
How are lipids involved in biological bilayers?
Phospholipids are the main component of biological bilayers known as membranes. They form when present in water due to its amphipathic nature.
Describe the four levels of permeability and what molecules would be included at each level.
Small and uncharged molecules (gases)
Small and polar molecules (water)
Polar and larger molecules (glucose)
Charged and/or polar and larger (ions, macromolecules, ATP)
What is the difference between peripheral proteins and lipid-anchored proteins?
Peripheral - bond to the polar heads
Lipid anchored - anchors using a tail that is inserted into the membrane
What is facilitated diffusion? What types of proteins are used and how?
Facilitated diffusion - movement of substances along gradient with the use of proteins
Channels - allow ions and other molecules, can be gated or specific
Transporters - allow for conformational change for larger molecules, can be a uniporter, symporter, or antiporter
What are the differences between the types of transporters?
Uniporter - movement of one solute
Symporter - movement of two solutes in the same direction
Antiporter - movement of two solutes in different directions