Plasma Membranes Flashcards
What is the primary function of biological membranes?
To act as a barrier that separates the interior of the cell from the external environment.
True or False: Biological membranes are rigid structures.
False
Fill in the blank: The fluid mosaic model describes the structure of biological membranes as a ________ of various components.
mixture
What are the main components of biological membranes?
Phospholipids, proteins, carbohydrates, and cholesterol.
Which part of the phospholipid molecule is hydrophobic?
The fatty acid tails.
What is the role of cholesterol in biological membranes?
To stabilize the membrane’s fluidity.
True or False: Proteins in the membrane can be integral or peripheral.
True
What is the term for the movement of substances across a membrane without the use of energy?
Passive transport.
Define osmosis.
The diffusion of water across a selectively permeable membrane.
What is the function of glycoproteins in the membrane?
To serve as recognition sites for cell signaling and communication.
Fill in the blank: The process by which cells take in large particles by engulfing them is called ________.
phagocytosis
Which type of transport requires energy?
Active transport.
What is the difference between facilitated diffusion and simple diffusion?
Facilitated diffusion requires specific transport proteins, while simple diffusion does not.
True or False: The lipid bilayer is permeable to all substances.
False
What is the main characteristic of a selectively permeable membrane?
It allows certain substances to pass while blocking others.
What is the role of transport proteins in the plasma membrane?
To facilitate the movement of substances across the membrane.
Define diffusion.
The net movement of particles from an area of higher concentration to an area of lower concentration.
What are aquaporins?
Channel proteins that facilitate water transport across cell membranes.
Fill in the blank: The ________ is the region of the membrane where the hydrophobic tails of phospholipids face each other.
lipid bilayer
What is endocytosis?
The process by which cells internalize substances from their external environment.
True or False: Membrane fluidity decreases with increasing temperature.
False
What is the significance of a concentration gradient in membrane transport?
It drives the movement of substances across the membrane.
What type of molecules can easily pass through the lipid bilayer?
Small nonpolar molecules.
Define exocytosis.
The process by which cells expel materials in vesicles that fuse with the plasma membrane.
