34 Questions
What is the main function of membrane transport in a cell?
To maintain internal equilibrium (homeostasis) by allowing the smooth movement of molecules across cell membranes.
Describe the composition of the plasma membrane.
The plasma membrane is a phospholipid bilayer that is semi-permeable and contains proteins.
What is a concentration gradient?
A concentration gradient is a difference in the concentration of a solute between two neighboring regions.
Explain the concept of simple diffusion in passive transport.
Simple diffusion is a form of passive transport where a substance moves down its concentration gradient without the use of a carrier molecule or protein.
How does active transport differ from passive transport?
Active transport requires energy input, while passive transport does not.
What is the role of gradient dissipation in cell transport?
Gradient dissipation occurs when solutes move and the gradient disappears, unless energy is expended to maintain it.
Why is membrane transport important for the cell?
Membrane transport is important for upholding cellular balance and necessary functions.
How does membrane transport separate the cell's inner realm from the external surroundings?
By controlling the movement of various molecules, ions, and substances across the cell membrane.
What types of substances can enter or leave cells by simple diffusion?
Lipids, oxygen, carbon dioxide
How does the extent of the concentration gradient affect the rate of diffusion?
The greater the difference in concentration, the more rapid the diffusion.
Explain why more massive molecules diffuse more slowly.
More massive molecules move more slowly because it is more difficult for them to move between the molecules of the substance they are moving through.
How does temperature affect the rate of diffusion?
Higher temperatures increase the energy and movement of molecules, thereby increasing the rate of diffusion.
What effect does solvent density have on the rate of diffusion?
As solvent density increases, the rate of diffusion decreases.
What is facilitated diffusion, and how does it differ from simple diffusion?
Facilitated diffusion involves the use of integral membrane proteins as channels or carriers to help substances pass through the membrane. It does not require energy.
Explain the difference between channel mediated diffusion and carrier mediated diffusion.
Channel mediated diffusion uses leak or gated channels to move substances, while carrier mediated diffusion uses carrier proteins.
What are the two types of proteins involved in facilitated diffusion?
Integral membrane proteins
What is the process that entails the diffusion of water molecules across a selectively permeable membrane?
Osmosis
What is the term used to describe a solution with the same solute concentration as the cell?
Isotonic solution
How does a cell respond when placed in a hypotonic solution?
It swells
What type of solution results in cell shrinking when a cell is placed in it?
Hypertonic solution
What is the process that requires energy input to move substances against their concentration gradient?
Active Transport
Which pump is responsible for the flow of impulses along nerve and muscle cells?
Sodium-Potassium Pump
What provides the energy for active transport?
ATP
What happens to the cell size when placed in an isotonic solution?
It remains constant
What is the role of ATP in the process of moving ions across the cell membrane?
ATP splits and the inorganic phosphate attaches to the carrier protein causing a conformational change, allowing the movement of ions.
How many Na+ ions can the carrier protein accommodate during the resting stage?
3 Na+ ions
What happens to the 3 Na+ ions once the carrier protein changes shape?
They are released to the outside of the cell.
How many K+ ions can the carrier protein take up from the outside after releasing Na+ ions?
2 K+ ions
What triggers the release of K+ ions inside the cell by the carrier protein?
The release of the inorganic phosphate (P) from the carrier protein.
What is the ratio of Na+ ions moved out of the cell to K+ ions moved into the cell?
3:2
What is the role of endocytosis in cellular processes?
Endocytosis allows the cell to engulf fluids and large molecules and bring them into the cell.
How does exocytosis differ from endocytosis?
Exocytosis transports fluids and large particles out of the cell using vesicles.
Describe what happens during exocytosis at the cell membrane.
Vesicles within the cell move to the cell membrane and join with it, releasing substances outside the membrane.
What initiates the movement of substances in and out of the cell through vesicles?
Conformational changes in carrier proteins and membrane-bound proteins.
Explore the process of membrane transport that allows the smooth movement of molecules across cell membranes, contributing to the maintenance of internal equilibrium in cells known as homeostasis. Learn about the structure of plasma membrane, its semi-permeable nature, and the role of proteins in facilitating transport.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
