Module 2 Flashcards
Term: Cell Membrane Composition
Definition: Cell membranes are composed of lipids, proteins, and carbohydrates, forming a selective barrier that controls the movement of molecules between the inside and outside of the cell.
Term: Amphipathic Phospholipids
Definition: Phospholipids have both hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails. They form a bilayer that makes up the cell membrane, providing a barrier to the external environment.
Term: Lipid Bilayer
Definition: A structure consisting of two layers of phospholipids where hydrophobic tails face inward, and hydrophilic heads face outward. It acts as a foundational structure of the cell membrane, allowing selective permeability.
Term: Role of Cholesterol in Membranes
Definition: Cholesterol is a component of animal cell membranes. It acts as a buffer to maintain membrane fluidity by preventing the membrane from becoming too rigid or too fluid in varying temperatures.
Term: Integral Membrane Proteins
Definition: Proteins that are permanently embedded in the cell membrane. They are crucial for functions such as transport, acting as receptors, and maintaining cell structure.
Term: Peripheral Membrane Proteins
Definition: These proteins are temporarily attached to the lipid bilayer or integral proteins through weak non-covalent interactions. They can be involved in signaling or maintaining the cell’s
Q: What is the role of the nuclear envelope in eukaryotic cells, and how does it contribute to cellular function?
A: The nuclear envelope surrounds the nucleus, separating it from the cytoplasm. It contains nuclear pores that regulate the exchange of materials (like RNA and proteins) between the nucleus and the rest of the cell, facilitating gene expression and DNA protection.
Q: How do mitochondria and chloroplasts support the endosymbiotic theory of evolution?
A: Both mitochondria and chloroplasts contain their own DNA and reproduce independently of the cell, similar to bacteria. This supports the endosymbiotic theory, which suggests these organelles evolved from free-living prokaryotes that were engulfed by ancestral eukaryotic cells.
Q: What is a vesicle, and how does it function in transport within the endomembrane system?
A: A vesicle is a small, membrane-bound sac that transports materials within the cell. Vesicles carry proteins and lipids between organelles in the endomembrane system (such as the ER, Golgi apparatus, and plasma membrane) through processes like exocytosis and endocytosis.
Q: What is the primary difference between autotrophic and heterotrophic organisms at the cellular level?
A: Autotrophs (like plants) produce their own food through photosynthesis in chloroplasts, using sunlight to convert CO2 into glucose. Heterotrophs (like animals) cannot produce their own food and must consume other organisms for energy.
Q: What are the key differences between plant and animal cells at the cellular level?
A: Plant cells have a cell wall, chloroplasts, and a large central vacuole, while animal cells do not. Plant cells also use chloroplasts for photosynthesis, while animal cells rely solely on mitochondria for energy production.
Q: How does the sodium/potassium pump maintain the electrochemical gradient in nerve cells?
A: The sodium/potassium pump actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, creating an electrochemical gradient. This gradient is essential for transmitting nerve impulses and maintaining membrane potential.
Q: What are the three main functions of the Golgi apparatus in a cell?
A: The Golgi apparatus functions to: 1) Modify proteins and lipids from the ER, 2) Sort these molecules for transport to their final destinations, and 3) Synthesize some cellular carbohydrates, such as polysaccharides used in the cell wall.
Q: How do lysosomes contribute to the recycling of cellular materials, and what happens if they malfunction?
A: Lysosomes contain enzymes that break down cellular debris, damaged organelles, and foreign particles. If lysosomes malfunction, waste materials can accumulate, leading to diseases like lysosomal storage disorders (e.g., Gaucher disease).
Q: Explain the structure of the phospholipid bilayer and how it influences membrane fluidity.
A: The phospholipid bilayer consists of two layers of phospholipids with hydrophobic tails facing inward and hydrophilic heads facing outward. This structure allows the membrane to be flexible while providing a barrier to most polar molecules. The presence of cholesterol within the bilayer further modulates membrane fluidity.
Q: What is the difference between primary and secondary active transport?
A: Primary active transport directly uses energy from ATP to move molecules against their concentration gradient, such as the sodium/potassium pump. Secondary active transport uses the energy stored in the gradient of one molecule (e.g., Na+) to drive the transport of another molecule (e.g., glucose) without directly using ATP.
Q: What are the three main components of cell membranes, and what is their function?
A: Cell membranes are composed of lipids, proteins, and carbohydrates. Lipids provide a hydrophobic barrier, proteins act as transporters and receptors, and carbohydrates are involved in cell recognition and communication.
Q: What is the primary function of the plasma membrane, and how does it maintain cellular homeostasis?
A: The plasma membrane acts as a selective barrier that controls the movement of molecules into and out of the cell, maintaining homeostasis by regulating nutrient intake, waste removal, and communication with other cells.
Q: Name two organelles involved in harnessing energy in cells and describe their specific roles.
A: Mitochondria generate ATP through cellular respiration, while chloroplasts in plant cells convert solar energy into chemical energy (glucose) via photosynthesis.
Q: What is the basic unit of life according to cell theory, and what are the three principles of cell theory?
A: The basic unit of life is the cell. The three principles are: 1) All living organisms are composed of cells. 2) The cell is the basic unit of life. 3) All cells come from preexisting cells.
Q: What are the three primary components of the endomembrane system, and what are their functions?
A: The nuclear envelope protects the DNA, the endoplasmic reticulum (ER) synthesizes proteins and lipids, and the Golgi apparatus modifies, sorts, and packages proteins for transport.
Q: Define diffusion and explain how it drives passive transport in cells.
A: Diffusion is the movement of molecules from an area of high concentration to low concentration, driving passive transport, where molecules move across membranes without energy input, down their concentration gradient.
Q: What is osmosis, and how does it differ from regular diffusion?
A: Osmosis is the diffusion of water across a selectively permeable membrane. It differs from regular diffusion because it specifically involves the movement of water to balance solute concentrations on both sides of the membrane.
Q: How does active transport differ from passive transport, and what energy source does active transport require?
A: Active transport requires energy (usually from ATP) to move molecules against their concentration gradient, whereas passive transport does not require energy and moves molecules along their concentration gradient.
