Questions and Answers
Plasma membranes are a feature of:
Which of the following is NOT a component of plasma membranes?
Which of the following is NOT true of the plasma membrane?
N-linked glycosylation is the attachment of a carbohydrate to a nitrogen atom, while O-linked glycosylation is the addition of sugars to the oxygen atom of certain side chains.
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The process of covalently attaching a carbohydrate to a protein or lipid is called:
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In eukaryotes, where does the synthesis of most lipids primarily occur?
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Facilitated diffusion but not passive diffusion requires energy.
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Exocytosis is the process by which material from inside of the cell is packaged into vesicles and excreted into the extracellular medium.
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The following solutes have very low permeability through the plasma membrane:
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Water can freely diffuse through animal cell membranes.
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Study Notes
Plasma Membranes
- Plasma membranes are present in all types of cells, including prokaryotic and eukaryotic cells.
- Key components of plasma membranes include phospholipids, cholesterol, glycosylated proteins, and glycolipids.
Composition and Structure
- Glycosylated nucleic acids are NOT a component of plasma membranes.
- The extracellular and intracellular leaflets of the plasma membrane are NOT highly symmetrical, contrasting with a common misconception about their structure.
- Peripheral proteins exist on the membrane surface, while integral proteins are embedded, spanning the membrane.
Glycosylation
- N-linked glycosylation involves attaching carbohydrates to the nitrogen of asparagine residues, while O-linked glycosylation attaches sugars to the oxygen of serine or threonine residues.
- Glycosylation is a process for covalently connecting carbohydrates to proteins or lipids, enhancing their functionality.
Lipid Synthesis
- Most lipid synthesis occurs at the cytosolic leaflet of the smooth endoplasmic reticulum (ER) membrane due to interactions with the endomembrane system and cytosol.
Transport Mechanisms
- Facilitated diffusion does NOT require energy, while passive diffusion also operates without it.
- Exocytosis involves packaging materials within vesicles for secretion from the cell into the extracellular space.
Membrane Permeability
- Charged polar molecules and macromolecules exhibit very low permeability through the plasma membrane, limiting their passive transport.
- Water cannot freely diffuse through animal cell membranes, highlighting the regulated nature of cellular water transport.
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Test your knowledge on plasma membranes with this ANSC 221 Quiz 4 flashcard set. Each card presents a question with multiple-choice answers, focusing on cell biology and the components of plasma membranes. Perfect for studying before your next exam!