30 Questions
What is the function of CCR5 in HIV infection?
It helps HIV infect the cell
What do membrane carbohydrates recognize on the surface of other cells?
Molecules containing carbohydrates
What determines the asymmetrical distribution of proteins, lipids, and carbohydrates in the plasma membrane?
The ER and Golgi apparatus
What is attached to lipids in glycolipids?
Carbohydrates
Where are membrane carbohydrates most commonly attached?
To proteins
What is the term for proteins with attached carbohydrates?
Glycoproteins
What is the main characteristic of passive transport across a membrane?
It is the diffusion of a substance without energy investment
What is the tendency of molecules in diffusion?
To spread out evenly into the available space
What is the direction of diffusion of substances in a population?
Directional, although individual molecules move randomly
What is the state at which the rate of diffusion is equal in both directions?
Dynamic equilibrium
What is the direction of net diffusion of a substance?
Towards the region of lower concentration
Why is the diffusion of a substance across a biological membrane considered passive transport?
Because no energy is expended by the cell to move substances
What is the result of membrane proteins mixing after 1 hour in a hybrid cell?
Mixed proteins are present
What happens to membranes as temperatures cool?
They switch from a fluid state to a solid state
What is the primary function of the sodium-potassium pump?
To pump Na+ out of the cell and K+ into the cell
Why are membranes rich in unsaturated fatty acids more fluid?
Because they prevent tight packing
What is the function of cholesterol in animal cell membranes at warm temperatures?
To restrain movement of phospholipids
What happens to the shape of the sodium-potassium pump protein after Na+ binding and phosphorylation?
The protein's shape changes to decrease its affinity for Na+
What is released outside the cell after phosphorylation of the sodium-potassium pump protein?
Na+
What is the role of cholesterol in animal cell membranes at cool temperatures?
To maintain fluidity by preventing tight packing
What do plants use to buffer membrane fluidity?
Related steroid lipids
What is gained by the sodium-potassium pump protein after releasing the phosphate group?
A higher affinity for Na+
What is the energy source used by the sodium-potassium pump?
ATP
What is the term for the process by which the sodium-potassium pump moves ions across the cell membrane?
Active transport
What is the process by which a cell takes in macromolecules?
Endocytosis
What is the type of endocytosis where a cell engulfs a particle in a vacuole?
Phagocytosis
What is the name of the process by which a cell engulfs a particle in a vacuole, and then fuses with a lysosome to digest the particle?
Phagocytosis
What is the term for the process of 'cellular drinking'?
Pinocytosis
What is the term for the process of 'cellular eating'?
Phagocytosis
How many types of endocytosis are there?
Three
Test your understanding of cell membrane interactions, including the rapid intermixing of cell surface antigens after formation of mouse-human heterokaryons. Learn about the effects of temperature on membrane structure and function. Assess your knowledge of membrane proteins and hybrid cells.
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