Chapter 6 Flashcards
(22 cards)
What is endocytosis?
Endocytosis is the transport of small molecules, macromolecules, large particles, and small cells into eukaryotic cells via invagination of the cell membrane and the formation of vesicles.
What occurs during exocytosis?
In exocytosis, materials in vesicles are secreted from the cell when the vesicles fuse with the cell membrane.
What is receptor-mediated endocytosis?
In receptor-mediated endocytosis, a specific receptor protein on the cell membrane binds to a particular macromolecule.
What is required for active transport across membranes?
Active transport requires the use of chemical-bond energy to move substances across membranes against their concentration or electrical gradients.
What is primary active transport?
In primary active transport, energy from the hydrolysis of ATP is used to move ions into or out of cells.
The sodium-potassium (Na-K) pump is an example.
What is secondary active transport?
Secondary active transport (co-transport) couples the passive movement of one substance down its concentration gradient to the movement of another substance against its concentration gradient through active transport.
What do membranes exhibit?
Membranes exhibit selective permeability, regulating which substances pass through them.
What is diffusion?
Diffusion is the movement of a solute from a region of higher concentration to a region of lower concentration.
What is osmosis?
In osmosis, water diffuses across a membrane from a region of higher water concentration to a region of lower water concentration.
What occurs in an isotonic environment?
In an isotonic environment, total solute concentrations on both sides of the cell membrane are equal.
What happens in a hypotonic solution?
If the solution surrounding a cell is hypotonic to the cell interior, more water enters the cell than leaves it, causing it to swell.
What happens in a hypertonic solution?
In a hypertonic solution, more water leaves the cell than enters it, causing it to shrivel.
How can a substance diffuse passively across a membrane?
A substance can diffuse passively across a membrane by either simple diffusion or facilitated diffusion, via a channel protein or a carrier protein.
What are biological membranes composed of?
Biological membranes consist of lipids, proteins, and carbohydrates.
What model describes the structure of biological membranes?
The fluid mosaic model describes a phospholipid bilayer in which proteins can move within the plane of the membrane.
What factors influence the properties of membranes?
The properties of membranes depend on nonpolar lipids, integral membrane proteins, peripheral membrane proteins, and anchored membrane proteins.
Why is the cell membrane important in cell adhesion?
The cell membrane is important for cell adhesion as cells must recognize and adhere to one another to assemble into tissues.
What role do membrane-associated proteins and carbohydrates play?
Membrane-associated proteins and carbohydrates are essential for cell recognition and cell adhesion.
What are cell junctions?
Cell junctions connect adjacent cells and include tight junctions, desmosomes, and gap junctions.
What is the function of tight junctions?
Tight junctions prevent the passage of molecules through intercellular spaces and restrict the movement of membrane proteins.
What do desmosomes do?
Desmosomes cause cells to adhere firmly to one another.
What is the purpose of gap junctions?
Gap junctions provide channels for communication between adjacent cells.
