31 Questions
What is the main function of the cytoplasmic membrane in a cell?
To form a selective barrier between the inside of the cell and its environment
What is the primary component of the cell membrane?
Phospholipid bilayer
What characterizes the arrangement of lipid molecules in an aqueous environment?
Hydrophobic portions are exposed to the aqueous-external environment
What is the main role of cholesterol in the cell membrane?
To regulate membrane fluidity and stability
Which component of the cell membrane enables the cell to concentrate specific metabolites and discard waste materials?
Proteins
What is the significance of the phospholipid bilayer in biological membranes?
It represents the most stable arrangement of lipid molecules in an aqueous environment
What is the main function of the integral membrane proteins?
Facilitate movement of the cell
Which type of interaction stabilizes the cell membrane?
Hydrophobic interactions between the tails
What is the fluid mosaic model of the cell membrane?
A fluid state that enables phospholipids and proteins to move on the membrane surface
What type of proteins are covalently bonded to a phospholipid or a fatty acid embedded in the lipid bilayer?
Lipid-anchored proteins
How do integral proteins differ from peripheral proteins?
Integral proteins are embedded within the lipid bilayer, while peripheral proteins are non-covalently bonded to the lipid bilayer.
What is the external surface of the major proteins of the cell membrane primarily composed of?
Hydrophobic regions
Which region of the phospholipid bilayer is highly non-polar?
Fatty acid region
0
The outer surface of the cell membrane faces the environment and makes contact with a variety of proteins in certain bacteria.
Which type of bond stabilizes the cell membrane by ionically interacting with the negative charge of the phospholipids?
Cations (e.g. Mg2+ and Ca2+)
What is the process known as when molecules move from an area of low concentration to high concentration, requiring energy from the cell?
Active transport
Which type of protein carries both molecules across the membrane in the same direction?
Symporters
What is the molecule most likely to be involved in simple diffusion, as it can easily pass through cell membranes?
Water
Which of the following describes the movement of particles down concentration gradient, with no ATP needed?
Simple diffusion
What is the primary function of lipid anchored proteins in the cell membrane?
Anchoring to the lipid bilayer
Which class of transport proteins transports molecules from one side of the membrane to the other?
Uniporters
What is the main characteristic of antiporters?
Transporting one molecule in one direction while transporting the second molecule in the opposite direction
What is the energy source for active transport?
High energy phosphate compounds like adenosine triphosphate (ATP)
What is the role of group translocation in energy-linked transport?
Modifying molecules during transport
What is the composition of the E. coli phosphotransferase system?
Composed of 24 proteins, all necessary for transporting a given sugar
What is the result of a conformational change in a transport protein during active transport?
Higher concentration of transported molecules inside the cell
What is the main difference between symporters and antiporters?
Symporters transport two molecules in the same direction, antiporters transport one molecule in each direction
What does passive transport involve?
No spending of energy, allowing solute to move down the concentration gradient
What is the main function of membrane transport proteins?
To carry solute through the membrane by a conformational change
What is the primary mechanism of energy-linked transport that involves chemically modifying molecules during their movement across the membrane?
Group translocation
What provides the phosphate group for phosphorylating sugars in the phosphotransferase system?
High energy phosphate compounds like adenosine triphosphate (ATP)
Test your knowledge about the structure of cell membranes, including prokaryotic cells, eukaryotic cells, plant cells, and animal cells. Learn about the selective barrier function and the role of the cytoplasmic membrane in cell physiology.
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