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15 questions · 3 topics · Made with PupilBot from the author's own notes
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Which description best explains the basic organization of the plasma membrane?
Answer: A lipid bilayer of amphipathic phospholipids stabilized by cholesterol, containing embedded proteins
The plasma membrane consists of an amphipathic phospholipid bilayer stabilized by cholesterol, with integral and peripheral proteins associated with it.
Which functions can be performed by integral membrane proteins in the plasma membrane?
Answer: Binding external ligands as receptors · Forming channels for movement of molecules across the membrane · Driving active transport as molecular pumps
Integral membrane proteins include receptors, channels, and pumps. Catalase is associated with peroxisomes, while ribosomal subunits participate in protein synthesis.
Compare phagocytosis, pinocytosis, and receptor-mediated endocytosis by identifying the type of material or molecule each process takes up.
Answer: Phagocytosis takes up particulate material; pinocytosis takes up dissolved substances or fluid; receptor-mediated endocytosis takes up specific molecules bound to integral membrane receptor proteins.
The three major forms of endocytosis differ mainly in the nature and selectivity of the material internalized: particles, dissolved substances or fluid, and specific receptor-bound molecules.
During exocytosis, cytoplasmic membrane vesicles ___ with the plasma membrane and release their contents into the ___ space.
Answer: Blank 1: fuse (also accept: merge). Blank 2: extracellular.
Exocytosis is a secretion process in which vesicles fuse with the plasma membrane and discharge their contents outside the cell.
A cell can internalize particulate material, dissolved substances, and specific molecules attached to membrane receptors. How many major types of endocytosis account for these three uptake mechanisms?
Answer: Value: 3 (exact, no tolerance).
The three major types are phagocytosis, pinocytosis, and receptor-mediated endocytosis.
Approximately what is the diameter of an intermediate filament?
Answer: Value: approximately 6–10 nm (accept any value from 6 nm through 10 nm; a range of 6–10 nm is preferred).
Intermediate filaments are approximately 6–10 nm in diameter, placing them between actin filaments and microtubules in typical size.
A vesicle must be transported across the cytoplasm. Which statements correctly describe cytoskeletal structures or motor proteins that can support this process?
Answer: Microtubules provide tracks for vesicle transport. · Kinesin and dynein can transport vesicles along microtubules. · Myosins move along actin filaments and can carry vesicles.
Microtubules serve as transport tracks for motor proteins such as kinesin and dynein, while myosins move along actin filaments and can also carry vesicles. Intermediate filaments are not described as the primary tracks for these transport mechanisms, and tubulin does not transport vesicles by digestion.
In the generated diagram, which cytoskeletal polymer is highlighted by its hollow cylindrical structure with a relatively wide diameter?
Answer: Microtubule
Microtubules are cylindrical hollow structures composed of tubulin and are approximately 25 nm in diameter, making them wider than actin and intermediate filaments.
Explain how actin filaments and myosin can contribute to endocytosis, cell cleavage after mitosis, and cell locomotion.
Answer: Actin filaments form dynamic structures that interact with binding proteins to regulate cytoplasmic stability and movement. Myosins bind to and move along actin filaments, carrying vesicles or producing cytoplasmic movement. Together, actin and myosin help drive endocytosis, cytokinetic cell cleavage after mitosis, and movement of cells across substrates.
Actin provides flexible, dynamic filaments, while myosin generates movement along those filaments. Their coordinated activity supports membrane uptake, division of the cytoplasm, and cellular locomotion.
The cytoskeleton contains three main polymer types: ___, actin filaments, and intermediate filaments.
Answer: Blank 1: microtubules (also accept: microtubule).
The three main cytoskeletal polymer types are microtubules, actin filaments or microfilaments, and intermediate filaments.
In the generated diagram, which process is most directly associated with the highlighted mitochondrial compartment?
Answer: The citric acid cycle and fatty-acid oxidation
The highlighted compartment is the mitochondrial matrix, which contains enzymes for fatty-acid oxidation and the citric acid cycle.
Which statements correctly connect mitochondrial features with energy production?
Answer: Mitochondria are major sites of ATP synthesis. · Mitochondria are especially abundant in cells or cell regions with high energy demands. · The mitochondrial matrix contains enzymes involved in fatty-acid oxidation and the citric acid cycle.
Mitochondria synthesize most cellular ATP and are concentrated where energy expenditure is high. Their matrix contains enzymes for fatty-acid oxidation and the citric acid cycle. ATP synthase is associated with the inner membrane, and mitochondria form by fusion of pre-existing mitochondria.
Explain how the structure of the mitochondrial inner membrane supports ATP production.
Answer: The inner membrane contains enzyme assemblies of the electron transport system and ATP synthase. Its many folds provide extensive membrane surface for these energy-producing components.
The inner membrane is specialized for energy production because it contains the electron transport system and ATP synthase. Its numerous folds increase the available surface area for these components.
Mitochondria usually form by the ___ of pre-existing mitochondria.
Answer: Blank 1: fusion.
Mitochondria are usually filamentous organelles and form through the fusion of pre-existing mitochondria.
How many membranes does a mitochondrion have according to its basic structural organization?
Answer: Value: 2 (exact, no tolerance): one outer membrane and one inner membrane.
A mitochondrion has a porous outer membrane and an inner membrane with many folds. The space between them is the intermembrane space, not a third membrane.
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