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45 Cards in this Set

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What type of molecule is a phospholipid?
Amphipathic, meaning it contains a hydrophilic region and a hydrophobic region.
What is selective permeability?
Allows certain molecules to cross it more easily than others.
How is a membrane held together?
Hydrophobic interactions.
How does cholesterol help membrane fluidity at low temperatures?
It acts a "temperature buffer" by hindering the close packing of phospholipids, thus lowering the temperature required for the membrane to solidify.
What is the difference between cytosol and cytoplasm?
The cytosol is the gel that flows through the cell, whereas the cytoplasm includes the cytosol, organelles, and inclusions.
What is the difference between integral proteins and peripheral proteins?
Integral proteins penetrate the hydrophobic core of the phospholipid bilayer. Peripheral proteins are not embedded in the lipid bilayer at all, but instead loosely bound to the surface of the membrane.
What is the difference between integral proteins and peripheral proteins?
Integral proteins penetrate the hydrophobic core of the phospholipid bilayer. Peripheral proteins are not embedded in the lipid bilayer at all, but instead loosely bound to the surface of the membrane.
What are glycolipids?
Carbohydrates covalently bonded to lipids.
What are glycoproteins?
Carbohydrates covalently bonded to proteins.
What organelles mainly manufacture the plasma membrane?
The ER and Golgi apparatus.
What type of molecules cross the lipid bilayer with the most ease?
Hydrophobic (nonpolar) molecules such as hydrocarbons, carbon dioxide, and oxygen.
How do hydrophilic molecules pass through the membrane?
Transport proteins.
What type of transport proteins facilitate the passage of water?
Aquaporins.
What are the two types of transport proteins and how do each function?
Channel proteins and carrier proteins. Channel proteins have a hydrophilic channel that hydrophobic molecules use as a tunnel. Carrier proteins hold onto the molecule and change shape in a way that shuttles them across the membrane.
What are the two modes of membrane traffic?
Passive transport and active transport.
Why does water require a transport protein to move rapidly and in large quantities across a membrane?
Water is a polar molecule. Therefore, it is hard for it to pass through the hydrophobic core of the membrane.
Any substance will diffuse down its _________.
Concentration gradient.
What mode of membrane traffic does not expend energy?
Passive Transport.
What is osmosis?
The diffusion of water across a selectively permeable membrane.
What is tonicity?
The ability of a solution to cause a cell to gain or lose water.
If there is no net movement of water across the membrane, what is the tonicity of the solution?
Isotonic.
.3M solute in beaker
.1M solute in bag
What tonicity is the bag?
Hypotonic.
What is osmoregulation?
The control of water balance.
What happens when a plant cell is placed in hypotonic solution?
The plant cell becomes turgid.
What happens when an animal cell is placed in hypertonic solution?
The animal cell crenates.
What happens when an animal cell is placed in hypotonic solution?
The animal cell expands and can possibly lyse if there is too much water.
What happens when a plant cell is placed in hypertonic solution?
Plasmolysis, the cell membrane tears away from the cell wall as it shrinks.
When transport proteins help molecules passively diffuse across the membrane, what is the process called?
Facilitated diffusion
How do gated channels in a transport protein function?
A stimulus (electrical or chemical) causes them to open or close. If the stimulus is chemical, the stimulus is a substance other than the one to be transported.
How can a molecule be transported against its concentration gradient?
Active transport.
What kind of transport proteins are involved in active transport?
Carrier proteins only.
What supplies the energy for a sodium-potassium pump? What type of membrane trafficking is this?
ATP powers the the pump by phosphorylating the protein. This phosphorylation changes the conformation of the protein, expelling Na+ and taking in K+. This is active transport because it uses energy.
The cytoplasm of a cell is ______ in charge compared to the extracellular fluid.
Negative.
What is membrane potential?
The voltage across a membrane.
An ion diffuses down its ________.
Electrochemical gradient.
What type of transport protein generates voltage?
An electrogenic pump.
How do plants load sucrose into the veins of leaves?
Cotransport.
What is the main electrogenic pump of plants, fungi, and bacteria?
A proton pump, which actively transports H+ ions out of the cell, transferring positive charge from the cytoplasm to the extracellular solution.
What is exocytosis?
The cell secretes macromolecules by the fusion of vesicles with the plasma membrane.
What is endocytosis?
The cell takes in macromolecules and particulate matter by forming new vesicles from the plasma membrane.
What are the three types of endocytosis?
Phagocytosis (cell eating)
Pinocytosis (cell drinking)
Receptor-mediated endocytosis
How does phagocytosis occur?
A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole. The particle is then digested by lysosomes containing hydrolytic enzymes.
How does pinocytosis occur?
The cell takes in droplets of extracellular fluids into tiny vesicles.
How does receptor-mediated endocytosis occur?
Ligands bind to receptor proteins, causing the cell to form a vesicle containing the ligand molecules. The receptors are then recycled.
What is a ligand?
Any molecule that binds specifically to a receptor site of another molecule.