Chapter 5 - Phospholipids Flashcards
What are in Phospholipid sheets?
Two fatty acids attached to a glycerol backbone with the third space linked to a phosphorylated molecule.
What is the structure of a phospholipid?
Contains a polar head (Phosphate Group) and a nonpolar tail (fatty acid). Globular proteins are inserted into the lipid bilayer. Nonpolar segments are with the nonpolar interior while the polar portions protrude out.
What is the main component of cell membranes?
Phospholipid bilayer
What is used to transport and communicate across the membrane?
Transmembrane proteins
What reinforces the membrane’s shape and anchoring?
Interior protein network
What contains glycoproteins and glycolipids?
Cell-surface markers
What is the difference and the same between a glycoprotein and a glycolipid?
Both are modified within the Golgi complex and have a sugar chain attached (polysaccharide). A glycoprotein is a protein and a glycolipid is a fat.
What fills the space between the phospholipid?
Cholesterol
How does a phospholipid form?
Polar water molecules repel the long nonpolar tails of the phospholipids while seeking partners for hydrogen bonding. The tails face each other so they do not encounter water.
Why does a phospholipid form?
It is spontaneous driven by the tendency of water molecules to form the maximum number of hydrogen bonds.
What holds the membrane together?
Hydrogen bonds
What makes a lipid bilayer stable?
Water’s affinity for hydrogen bonding never stops
What can alter the degree of fluidity of the plasma membrane?
This can be altered by either changing the fatty acid composition, the amount of cholesterol, and changes in the environment like temperature.
What are transporters?
Allows only selective solutes to enter or leave the cell through channels of carriers composed of proteins.
What are enzymes?
Biological catalyst, usually a protein that increases rate of specific reactions without being consumed in the reaction.
What are cell-surface identity markers?
A combination of cell-surface proteins and glycoproteins that carry markers that identify them to other cells.
What are cell-surface receptors?
Receptor proteins that detect chemical messages which are anchored to the cell’s surface.
What are cell-to-cell adhesion proteins?
Uses specific proteins to glue themselves to one another.
What are cytoskeleton anchors?
Surface proteins that interact with other cells are firmly anchored to the cytoskeleton of the cell interior by linking proteins.
What is the hydrophobic region of a transmembrane protein that anchors it in the membrane?
Transmembrane domain - Often composed of alpha helixes but sometimes utilizes beta pleated sheets that form a barrel which opens at both ends called a pore.
What does the pore allow to pass?
The openings allow polar water molecules to pass through the membrane.
What is the net movement of dissolved molecules or other particles from a region of high concentration to low concentration?
Diffusion
What is carrier-assisted diffusion called?
Facilitated diffusion
What allows the diffusion of K+, NA+, or CA2 across the membrane and has an aqueous channel?
Ion Channels
What is a carrier protein?
A membrane protein that binds to specific molecules that cannot cross the membrane and allows passage through the membrane.
What is it called when a membrane is permeable to some substances but not others?
Selectively permeable membrane
What is the diffusion of water across a selectively permeable membrane?
Osmosis
What is it called when two solutions with different osmotic concentrations are separated by a water-permeable membrane and water moves to the side with higher concentration?
Osmotic Concentration
What is the difference between hypertonic and hypotonic?
Hypertonic is a solution with a higher concentration of solutes than cell. Hypotonic is a solution with a lower concentration than a cell.
When does a cell lose water by osmosis?
In a hypertonic solution
When does a cell gain water by osmosis?
In a hypotonic solution
What does it mean when the cell and the solution have the same amount of concentration?
Isotonic…the cell takes in and loses the same amount of water.
What is an aquaporin?
A channel that allows water to cross the membrane more easily than diffusion.
What stops the osmotic flow across a water membrane?
Osmotic pressure
What is the term for when a plant cell is rigid due to water intake?
Turgor pressure
What type of diffusion needs ATP to move molecules across a cellular membrane from lower to higher concentration?
Active Transport
What is the difference between a uniporter, symporter, and a antiporter?
A uniporter only transports one molecule or ion. A symporter transports two molecules or ions in the same direction across the membrane and a antiporter carries two molecules or ions in the opposite direction across the membrane.
What transports NA+ in exchange for K+ needing ATP due to the ions moving against their concentration gradients?
Sodium-potassium Pump
What are the two types of transports?
Coupled transport where energy is released as one molecule moves down its concentration gradient is used to move a different molecule against its gradient.
Countertransport NA+ and glucose move in the same direction across the membrane and the inward movement of NA+ is coupled with the outward movement of another substance such as CA+ or H+
What are phagocytosis and pinocytosis part of?
Endocytosis
What is it called when a cell takes in a solid particle?
Phagocytosis
What is the intake of fluid?
Pinocytosis
What is it called when a cell expels its contents ?
Exocytosis
