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What is the head of a phospholipid made of?
What is the head of a phospholipid made of?
A glycerol molecule attached to a phosphate group, which is often linked to choline or ethanolamine.
What are cell membranes mainly constructed of?
What are cell membranes mainly constructed of?
Phospholipids.
What is the function of carbohydrates in the cell membrane?
What is the function of carbohydrates in the cell membrane?
Cell recognition and communication.
What are the functions of proteins in cell membranes? (Select all that apply)
What are the functions of proteins in cell membranes? (Select all that apply)
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What are the types of solutions that affect water movement in and out of cells? (Select all that apply)
What are the types of solutions that affect water movement in and out of cells? (Select all that apply)
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Which of the following statements is TRUE about osmosis?
Which of the following statements is TRUE about osmosis?
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What is reverse osmosis?
What is reverse osmosis?
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Which of the following is an example of osmosis in everyday life?
Which of the following is an example of osmosis in everyday life?
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What is dialysis?
What is dialysis?
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Which of the following is NOT a type of diffusion?
Which of the following is NOT a type of diffusion?
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What is the function of the cell membrane?
What is the function of the cell membrane?
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What are the 7 functions of the cell membrane?
What are the 7 functions of the cell membrane?
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Which of the following is NOT a component of the cell membrane?
Which of the following is NOT a component of the cell membrane?
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What are the three types of proteins in the cell membrane? (Select all that apply)
What are the three types of proteins in the cell membrane? (Select all that apply)
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Cell membranes are fluid and flexible.
Cell membranes are fluid and flexible.
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Which of the following is NOT a function of proteins in the cell membrane?
Which of the following is NOT a function of proteins in the cell membrane?
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Which of the following BEST describes the main purpose of the cell membrane?
Which of the following BEST describes the main purpose of the cell membrane?
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Membranes are soluble in water.
Membranes are soluble in water.
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What would happen if a cell had no cell membrane?
What would happen if a cell had no cell membrane?
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What is the main function of phospholipids in the cell membrane?
What is the main function of phospholipids in the cell membrane?
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Osmosis is an active transport process.
Osmosis is an active transport process.
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Which of the following BEST describes the process used by the sodium-potassium pump?
Which of the following BEST describes the process used by the sodium-potassium pump?
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Which of the following is NOT a characteristic of passive transport?
Which of the following is NOT a characteristic of passive transport?
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Which of the following factors does NOT affect the rate of diffusion across a cell membrane?
Which of the following factors does NOT affect the rate of diffusion across a cell membrane?
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Which of the following INCREASES the rate of diffusion across a cell membrane?
Which of the following INCREASES the rate of diffusion across a cell membrane?
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Which of the following factors does NOT increase the rate of diffusion?
Which of the following factors does NOT increase the rate of diffusion?
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What are the 3 factors that increase the rate of diffusion?
What are the 3 factors that increase the rate of diffusion?
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What are the 3 factors that affect the rate of diffusion across the plasma membrane?
What are the 3 factors that affect the rate of diffusion across the plasma membrane?
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When we graphed the rate of diffusion (dn/dt) as a function of the concentration gradient (dC/dx), what does the slope of the line represent?
When we graphed the rate of diffusion (dn/dt) as a function of the concentration gradient (dC/dx), what does the slope of the line represent?
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What does an increase in the slope of the line in this graph (dn/dt vs. dC/dx) biologically indicate?
What does an increase in the slope of the line in this graph (dn/dt vs. dC/dx) biologically indicate?
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If the concentration gradient is constant, what happens to the rate of diffusion (dn/dt) as the surface area (A) of the cell increases?
If the concentration gradient is constant, what happens to the rate of diffusion (dn/dt) as the surface area (A) of the cell increases?
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If the concentration gradient is constant, what happens to the rate of diffusion (dn/dt) as the permeability (P) of the diffusing molecule increases?
If the concentration gradient is constant, what happens to the rate of diffusion (dn/dt) as the permeability (P) of the diffusing molecule increases?
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If the rate of diffusion is graphed as a function of the surface area (A) of the cell or the permeability (P) of the diffusing molecule, the graph would be a straight, upward-sloping line.
If the rate of diffusion is graphed as a function of the surface area (A) of the cell or the permeability (P) of the diffusing molecule, the graph would be a straight, upward-sloping line.
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Study Notes
Phospholipid Structure
- Phospholipids have a hydrophilic (water-loving) head and hydrophobic (water-fearing) tails.
- The head is made of a glycerol molecule attached to a phosphate group, often linked to choline or ethanolamine.
Cell Membrane Structure
- Cell membranes are primarily composed of a phospholipid bilayer.
- The bilayer consists of hydrophilic heads facing outwards towards the surrounding fluid, and hydrophobic tails facing inwards, away from the water.
Carbohydrate Function in Cell Membranes
- Carbohydrates in cell membranes are involved in cell recognition and communication.
- They are often attached to proteins (forming glycoproteins) or lipids (forming glycolipids).
- Carbohydrates aid in self-cell recognition, communication between cells, and offer protection against harmful agents.
Protein Functions in Cell Membranes
- Membrane proteins are crucial for various cell functions.
- Transport proteins facilitate substance movement across the membrane.
- Signaling proteins receive and transmit signals.
- Support proteins maintain cell shape.
- Recognition proteins help cells recognise each other.
- Catalytic proteins (enzymes) speed up chemical reactions.
Isotonic, Hypertonic, and Hypotonic Solutions
- Isotonic solutions have equal solute concentrations inside and outside the cell, resulting in no change in cell size.
- Hypertonic solutions have a higher solute concentration outside the cell, causing water to leave the cell and shrink it.
- Hypotonic solutions have a lower solute concentration outside the cell, causing water to enter and swell the cell.
Osmosis vs. Diffusion
- Osmosis is the movement of water across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration.
- Diffusion is the movement of molecules from an area of high concentration to an area of low concentration in air, liquids, or across a membrane.
- Osmosis specifically involves water movement, while diffusion applies to any molecule.
Reverse Osmosis
- Reverse osmosis forces water across a semipermeable membrane from an area of high solute concentration to an area of low solute concentration using pressure.
- This process removes impurities, producing pure water, and is used in water purification.
Examples of Osmosis in Everyday Life
- Plants absorb water from the soil through osmosis.
- Salting vegetables causes water to move out of their cells, leading to shrinkage.
- Kidney function maintains water and salt balance through osmosis.
Dialysis
- Dialysis removes waste, excess water, and toxins from the blood when the kidneys are not functioning, using a filter.
- Hemodialysis uses a machine to filter blood, while peritoneal dialysis uses the lining of the abdomen.
Types of Diffusion
- Simple diffusion: Molecules move from high to low concentration across a membrane without energy.
- Facilitated diffusion: Molecules move from high to low concentration using transport proteins without energy.
- Osmosis: Water moves from low to high solute concentration using a semi-permeable membrane.
- Active diffusion: Molecules move from low to high concentration using energy (ATP).
Cell Membrane Function
- Selective permeability: Regulates what enters and exits the cell.
- Protection and support: Protects the cell's contents and maintains its shape.
- Communication: Receives signals from the external environment.
- Cell recognition: Helps cells recognize each other.
- Anchoring cytoskeleton: Connects the membrane to the cell's internal framework.
- Transport: Facilitates the movement of substances across the membrane.
Cell Membrane Composition
- Phospholipids: Form the bilayer foundation of the membrane.
- Proteins: Embedded in or on the membrane, aiding transport and communication.
- Carbohydrates: Linked to proteins, facilitating cell recognition.
- Cholesterol: Contributes to membrane fluidity and stability.
Membrane Proteins
- Peripheral proteins: Located on the membrane surface, involved in structural support and cell communication.
- Integral proteins: Span the membrane, functioning as channels or transporters.
- Glycoproteins: Linked to carbohydrates, involved in cell recognition.
Membrane Fluidity and Flexibility
- Phospholipid arrangement and cholesterol content contribute to membrane fluidity and flexibility.
- Membranes can change shape and adapt easily.
Main Functions of Membrane Proteins
- Transport, reception, structural support, and cell recognition.
Main Purpose of Cell Membrane
- Regulate substance movement, maintain internal balance (homeostasis), and protect from harmful substances.
Membrane Solubility
- Cell membranes are not soluble in water, due to their hydrophobic tails.
Cell without Membrane
- Loss of protection, inability to regulate substance movement, cell destruction, impaired communication, cessation of vital functions.
Phospholipid Functions
- Form the cell membrane, maintain stability, control material passage, and organize proteins.
Osmosis: Active or Passive?
- Osmosis is a passive transport process, requiring no energy (ATP).
Sodium-Potassium Pump
- The sodium-potassium pump is an active transport process that moves sodium ions out of the cell and potassium ions into the cell against their concentration gradients, requiring ATP.
Difference between Active and Passive Transport
- Active transport requires energy (ATP) to move substances against their concentration gradients.
- Passive transport does not require energy and moves substances down their concentration gradients.
Factors Affecting Diffusion Rate
- Concentration gradient difference (higher difference, faster diffusion).
- Temperature (higher temperature, faster diffusion).
- Molecule size (smaller molecules, faster diffusion).
- Membrane properties (thickness, permeability).
- Medium type.
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Description
This quiz covers the essential components and functions of cell membranes, focusing on phospholipids, carbohydrates, and proteins. You will explore how these elements contribute to membrane structure and cellular communication. Test your knowledge of the intricate processes that keep cells functioning.
