pack Flashcards
What is the lipid bilayer?
The lipid bilayer is a permeability barrier.
What is the function of the plasma (cell) membrane?
The plasma (cell) membrane acts as a barrier but allows nutrients to enter and wastes to exit.
What determines what moves in and out of a cell?
Permeability determines what moves in and out of a cell.
What does selectively permeable mean for the plasma membrane?
A selectively permeable plasma membrane allows some materials to move freely while restricting others.
What are the factors that selective permeability is based on?
Selective permeability restricts materials based on size electrical charge molecular shape and lipid solubility.
What materials diffuse through the plasma membrane by simple diffusion?
Materials that diffuse through the plasma membrane by simple diffusion include lipid-soluble compounds (such as alcohols fatty acids and steroids) and dissolved gases (like oxygen and carbon dioxide).
What is channel-mediated diffusion?
Channel-mediated diffusion is the diffusion of water-soluble compounds and ions through the plasma membrane.
What factors affect channel-mediated diffusion?
Factors affecting channel-mediated diffusion include size charge and interaction with the channel (leak channels).
What is passive transport through a plasma membrane?
Passive transport through a plasma membrane does not require energy.
What is active transport through a plasma membrane?
Active transport through a plasma membrane requires energy and ATP.
What are the types of transport that can be passive?
Diffusion and carrier-mediated transport can be passive.
What are the types of transport that can be active?
Carrier-mediated transport and vesicular transport can be active.
What is diffusion?
Diffusion is a passive transport process where molecules move from an area of higher concentration to an area of lower concentration.
What is carrier-mediated transport?
Carrier-mediated transport can be either passive or active depending on whether energy is required.
What is vesicular transport?
Vesicular transport is an active transport process that requires energy.
How does molecule size affect diffusion?
Smaller molecules diffuse faster.
How does temperature affect diffusion?
Higher temperatures increase the motion of particles making diffusion faster.
What is a concentration gradient?
A concentration gradient is the difference between high and low concentrations.
How do electrical forces influence diffusion?
Electrical forces influence diffusion by attracting opposite charges and repelling like charges.
What are the two types of diffusion across plasma membranes?
Diffusion across plasma membranes can be simple or channel mediated.
What materials diffuse through the plasma membrane by simple diffusion?
Materials that diffuse through the plasma membrane by simple diffusion include lipid-soluble compounds such as alcohols fatty acids and steroids and dissolved gases such as oxygen and carbon dioxide.
What are the factors influencing channel-mediated diffusion?
Factors influencing channel-mediated diffusion include size charge and interaction with the channel such as leak channels.
What are water channels?
Water channels are specialized channels that allow water molecules to pass through the plasma membrane.
What are ion channels?
Ion channels are specific channels that allow ions to diffuse across the plasma membrane.
What are open channels?
Open channels are channels that remain open all the time allowing continuous diffusion of specific molecules.
What are gated channels?
Gated channels are channels that open or close in response to a stimulus.
What are chemically gated channels?
Chemically gated channels are channels that open or close in response to specific chemicals binding to them.
What are voltage-gated channels?
Voltage-gated channels are channels that open or close in response to changes in membrane potential.
What are mechanically gated channels?
Mechanically gated channels are channels that open or close in response to physical deformation of the membrane such as pressure or stretch.
What are the characteristics of carrier-mediated transport?
The characteristics of carrier-mediated transport include specificity saturation limits and regulation.
What does specificity mean in carrier-mediated transport?
Specificity means that one transport protein transports one set of substrates.
What are saturation limits in carrier-mediated transport?
Saturation limits refer to the fact that the rate of transport depends on the number of transport proteins available not the amount of substrate.
What does regulation mean in carrier-mediated transport?
Regulation in carrier-mediated transport involves cofactors such as hormones that can influence the activity of transport proteins.
What is cotransport in carrier-mediated transport?
Cotransport is when two substances move in the same direction at the same time through a transport protein.
What is counter-transport in carrier-mediated transport?
Counter-transport is when one substance moves into the cell while another moves out through a transport protein.
How do carrier proteins transport large molecules like glucose and amino acids?
Carrier proteins transport large molecules by binding them to a receptor site changing shape and allowing the molecules to pass through.
What happens when a molecule binds to a receptor site on a carrier protein?
When a molecule binds to a receptor site on a carrier protein the protein changes shape allowing the molecule to pass through.
What is the specificity of receptor sites on carrier proteins?
Receptor sites on carrier proteins are specific to certain molecules ensuring that only the correct molecules are transported.
What do active transport proteins do?
Active transport proteins move substrates against the concentration gradient and require energy such as ATP.
What are ion pumps?
Ion pumps are active transport proteins that move ions such as Na+ K+ Ca2+ and Mg2+ against their concentration gradients.
What is an exchange pump?
An exchange pump is a type of active transport protein that counter-transports two ions in opposite directions at the same time.
What is primary active transport?
Primary active transport is a process where transport proteins use energy directly from ATP to move substances against their concentration gradient.
What does the sodium-potassium exchange pump do?
The sodium-potassium exchange pump is a carrier-mediated active transport process that moves sodium ions Na+ out of the cell and potassium ions K+ into the cell.
How many ions does the sodium-potassium exchange pump move per ATP?
The sodium-potassium exchange pump moves 3 sodium ions Na+ out of the cell and 2 potassium ions K+ into the cell per ATP.
How does Na+ concentration gradient drive glucose transport in secondary active transport?
In secondary active transport the Na+ concentration gradient provides the energy to transport glucose against its concentration gradient into the cell.
How is ATP involved in secondary active transport?
In secondary active transport ATP energy is used to pump Na+ back out of the cell to maintain the Na+ concentration gradient.
How does osmosis relate to solute and water concentration?
In osmosis water molecules diffuse toward the solution with more solutes resulting in a lower concentration of free water molecules on that side.
What must a membrane be for osmosis to occur?
For osmosis to occur the membrane must be freely permeable to water and selectively permeable to solutes.
What happens to water molecules during osmosis?
During osmosis water molecules diffuse across the membrane toward the solution with a higher concentration of solutes.
What happens to the volume on the side with more solutes during osmosis?
The volume increases on the side with more solutes during osmosis.
What is endocytosis?
Endocytosis is a type of active transport using ATP where materials are brought into the cell within vesicles.
What are the three types of endocytosis?
The three types of endocytosis are receptor-mediated endocytosis pinocytosis and phagocytosis.
What happens during receptor-mediated endocytosis?
During receptor-mediated endocytosis receptors (glycoproteins) on the cell membrane bind to target molecules (ligands) and a coated vesicle (endosome) carries these ligands and receptors into the cell.
What is pinocytosis?
Pinocytosis is a form of endocytosis where the cell engulfs extracellular fluid containing dissolved substances into small vesicles.
What is phagocytosis?
Phagocytosis is a form of endocytosis where the cell engulfs large particles or debris into vesicles called phagosomes.
What is endocytosis in vesicular transport?
Endocytosis is a type of vesicular transport where materials are brought into the cell from the outside.
What is pinocytosis?
Pinocytosis is a form of endocytosis where endosomes “drink” extracellular fluid.
What is phagocytosis?
Phagocytosis is a form of endocytosis where pseudopodia or “false feet” extend to engulf large objects into vesicles called phagosomes.
What does pseudopodia mean?
Pseudopodia means “false feet” and are extensions of the cell membrane used in phagocytosis to engulf large objects.
What is the basal membrane in epithelial transport?
The basal membrane is the surface of epithelial cells that faces the underlying connective tissue and is opposite the apical membrane.
What is paracellular transport?
Paracellular transport is the movement of substances through the junctions between adjacent cells.
What is transcellular transport?
Transcellular transport is the movement of substances directly through the cells themselves.
What is transcytosis with vesicular transport?
Transcytosis with vesicular transport involves the movement of substances across a cell by vesicles that encapsulate the material for transport.
What is the difference between absorption and secretion in epithelial transport?
Absorption is the process of moving substances from the lumen to the extracellular fluid (ECF) while secretion is the movement of substances from the ECF to the lumen.
How does transcellular transport of glucose occur?
Transcellular transport of glucose occurs through the use of membrane proteins that facilitate its movement across the cell membrane.
