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Questions and Answers
What is the primary function of pumps in cells?
What is the primary function of pumps in cells?
In primary active transport, what is the direct source of energy?
In primary active transport, what is the direct source of energy?
What is the primary characteristic of voltage-gated channels?
What is the primary characteristic of voltage-gated channels?
What type of transport is used for molecules that are too large to be moved by transport proteins?
What type of transport is used for molecules that are too large to be moved by transport proteins?
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What is the name of the pump that moves sodium ions out of the cell and potassium ions into the cell?
What is the name of the pump that moves sodium ions out of the cell and potassium ions into the cell?
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What is the main function of the glycocalyx in some cells?
What is the main function of the glycocalyx in some cells?
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What is the term for the binding of a chemical substance to a channel protein, opening or closing the gate?
What is the term for the binding of a chemical substance to a channel protein, opening or closing the gate?
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Which of the following substances can penetrate the lipid layer of the membrane with ease?
Which of the following substances can penetrate the lipid layer of the membrane with ease?
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What is the primary function of integral proteins?
What is the primary function of integral proteins?
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What is the term for the loose carbohydrate coat on the outside surface of the cell?
What is the term for the loose carbohydrate coat on the outside surface of the cell?
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Which of the following is NOT a function of membrane carbohydrates?
Which of the following is NOT a function of membrane carbohydrates?
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What is the main function of cholesterol in the cell membrane?
What is the main function of cholesterol in the cell membrane?
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What type of proteins are involved in the regulation of metabolism and signal transfer?
What type of proteins are involved in the regulation of metabolism and signal transfer?
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Which type of protein forms structural channels through which water-soluble substances can diffuse?
Which type of protein forms structural channels through which water-soluble substances can diffuse?
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What is the primary role of structural proteins in the cell membrane?
What is the primary role of structural proteins in the cell membrane?
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What is the function of sphingolipids in the cell membrane?
What is the function of sphingolipids in the cell membrane?
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What is the primary function of carrier proteins in the cell membrane?
What is the primary function of carrier proteins in the cell membrane?
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What is the main function of peripheral proteins in the cell membrane?
What is the main function of peripheral proteins in the cell membrane?
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What is the result of the fusion of a vesicle with the plasma membrane during exocytosis?
What is the result of the fusion of a vesicle with the plasma membrane during exocytosis?
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What type of endocytosis involves the engulfment of solid particles such as bacteria?
What type of endocytosis involves the engulfment of solid particles such as bacteria?
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What is the role of clathrin in receptor-mediated endocytosis?
What is the role of clathrin in receptor-mediated endocytosis?
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What is the term for the process by which cells take in extracellular substances through the formation of vesicles?
What is the term for the process by which cells take in extracellular substances through the formation of vesicles?
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What type of endocytosis involves the uptake of liquid or very small particles?
What type of endocytosis involves the uptake of liquid or very small particles?
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What is the process by which cells release cellular products into the extracellular fluid?
What is the process by which cells release cellular products into the extracellular fluid?
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What is the purpose of actin and other contractile fibrils surrounding the phagocytic vesicle?
What is the purpose of actin and other contractile fibrils surrounding the phagocytic vesicle?
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What is the primary function of lysosomes in cells?
What is the primary function of lysosomes in cells?
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What is the role of lysozyme in the phagocytic process?
What is the role of lysozyme in the phagocytic process?
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What is the primary purpose of autophagy in cells?
What is the primary purpose of autophagy in cells?
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What happens to worn-out cell organelles inside the lysosome?
What happens to worn-out cell organelles inside the lysosome?
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What is the role of autophagy in tissue development and cell survival?
What is the role of autophagy in tissue development and cell survival?
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Study Notes
Cell Membrane Structure
- The cell membrane consists of a lipid layer with embedded proteins, as well as carbohydrates attached to the outer surface.
- The lipid layer is impermeable to water-soluble substances, such as ions, glucose, and urea, but allows fat-soluble substances, like oxygen, carbon dioxide, and alcohol, to pass through.
Membrane Carbohydrates
- Membrane carbohydrates, known as proteoglycans, are mainly carbohydrate substances bound to small protein cores.
- The glycocalyx, a loose carbohydrate coat on the cell surface, plays a crucial role in various functions, including:
- Repelling negatively charged substances
- Attaching cells to each other
- Acting as receptors for binding hormones
- Participating in immune reactions
Membrane Proteins
- Membrane proteins can be categorized into two main types:
- Integral proteins:Embedded in the lipid bilayer and span the entire membrane.
- Peripheral proteins:Attached to the outer or inner surface of the membrane.
Functions of Membrane Proteins
- Membrane proteins perform various functions, including:
- Structural roles: Connecting the membrane to the cytoskeleton and creating cell junctions.
- Enzymatic activities: Catalyzing chemical reactions.
- Transport: Facilitating the movement of substances across the membrane.
- Receptor functions: Binding to hormones and other signaling molecules.
Cell Transport Systems
- Cell membranes are selectively permeable, controlling the movement of substances into and out of the cell.
- There are three main types of cell transport systems:
- Passive transport: Substances move from an area of high concentration to an area of low concentration.
- Active transport: Substances move against their concentration gradient, requiring energy input.
- Bulk transport: Large molecules and particles are transported through endocytosis and exocytosis.
Passive Transport
- Passive transport mechanisms include:
- Diffusion: Substances move from an area of high concentration to an area of low concentration.
- Osmosis: Water molecules move from an area of high concentration to an area of low concentration.
- Facilitated diffusion: Substances move through specific channels or carriers.
Active Transport
- Active transport mechanisms include:
- Primary active transport: Energy is derived directly from ATP or other high-energy phosphate compounds.
- Secondary active transport: Energy is derived from ionic concentration differences created by primary active transport.
Bulk Transport
- Bulk transport mechanisms include:
- Endocytosis: Large molecules and particles are engulfed by the cell membrane, forming vesicles.
- Exocytosis: Vesicles fuse with the cell membrane, releasing their contents outside the cell.
Lysosomes
- Lysosomes are membrane-bound organelles that contain digestive enzymes and acids.
- Functions of lysosomes include:
- Digesting foreign substances, such as bacteria
- Removing damaged cellular components
- Recycling cellular materials
Autophagy
- Autophagy is a process in which cells recycle damaged or dysfunctional organelles and proteins.
- Autophagy involves the delivery of intracellular components to lysosomes for degradation and recycling.
- Autophagy plays a crucial role in maintaining cellular health and homeostasis.
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Description
Learn about the composition and properties of the cell membrane, including its lipid layer and associated carbohydrates. Understand how it regulates the passage of substances into and out of the cell.
