Membranes Flashcards
What makes up a plasma membrane?
- Lipids
- Proteins
- Carbohydrates
The one class of large biological molecules that does not include true polymers
Lipids
Fats are comprised of
- Glycerol
- Fatty Acids
A carboxyl group attached to a long carbon skeleton
Fatty Acid
____fatty acids have the maximum number of hydrogen atoms possible and no double bonds
Saturated
____ fatty acids have one or more double bonds
Unsaturated
Two fatty acids and a phosphate group, attached to glycerol, make a
phospholipid
What is an amphipathic molecule?
Contains hydrophilic and hydrophobic regions
Example: phospholipids
Lipids characterized by a carbon skeleton consisting of four fused rings
Steroids
A precursor from which other steroids are synthesized
Cholesterol
____ proteins are bound to the surface of the membrane
Peripheral
____ proteins penetrate the hydrophobic core
Integral
These are examples of
- Transport
- Enzymatic activity
- Signal transduction
- Cell-cell recognition
- Intercellular joining
- Attachment to the cytoskeleton and extracellular matrix (ECM)
Functions of membrane proteins
____ allow passage of hydrophilic substances across the membrane
Transport proteins
Channel proteins that facilitate the passage of water molecules
aquaporins
The tendency for molecules to spread out evenly into the available space
Diffusion
Diffusion across a membrane with no energy investment
Passive Transport
The diffusion of water across a selectively permeable membrane
Osmosis
The ability of a surrounding solution to cause a cell to gain or lose water
Tonicity
No net water movement across the plasma membrane
Isotonic Solution
Hypertonic Solution
Cell loses water
Hypotonic Solution
Cell takes on water
Transport proteins speed the passive movement of molecules across the plasma membrane
Facilitated Diffusion
What do ion channels do?
Help shuttle ions across a cell membrane
____ allows cells to maintain concentration gradients that differ from their surroundings
Active Transport
Uses ATP
A transport protein that is energized by transfer of a phosphate group from the hydrolysis of ATP
Sodium-potassium pump
What is membrane potential?
The voltage across a membrane
What two forces power the electrochemical gradient?
- A chemical force
- An electrical force
A transport protein that generates voltage across a membrane
An electrogenic pump
A ____ pump actively transports hydrogen ions (H+) out of the cell
proton
When active transport of a solute indirectly drives the transport of other substances
Cotransport
What happens in exocytosis?
A vesicle vomits its content outside the cell
Example: dead organelles, intruders, general cell trash
These are the three types of
- Phagocytosis-cellular eating
- Pinocytosis-cellular drinking
- Receptor-mediated
Endocytosis
