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General Biology: Cell Biology and Energy

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  • Where is DNA located in a prokaryotic cell?
    DNA is located in the nucleoid region, which is not membrane-bound.
  • What features are shared by both eukaryotic and prokaryotic cells?
    Both have plasma membranes, cytoplasm, ribosomes, and DNA.
  • Describe the structure and function of the nuclear envelope.
    The nuclear envelope is a double membrane with pores that regulates molecule passage in and out of the nucleus.
  • What is chromatin?
    Chromatin is DNA wrapped around proteins, forming a complex that packages DNA inside the nucleus.
  • What is the function of ribosomes?
    Ribosomes synthesize proteins by translating mRNA.
  • What is the function of the rough endoplasmic reticulum (ER)?
    The rough ER produces proteins, especially those destined for secretion or membranes.
  • What are the functions of the smooth endoplasmic reticulum (ER)?
    The smooth ER synthesizes lipids, detoxifies chemicals, and stores calcium ions.
  • What is the role of the Golgi apparatus?
    The Golgi apparatus modifies, sorts, and ships proteins and lipids received from the ER.
  • What is the function of lysosomes?
    Lysosomes contain enzymes that digest damaged organelles and macromolecules.
  • Why do plant cells have a central vacuole?
    The central vacuole stores water and maintains turgor pressure to support the cell.
  • What is the function of mitochondria?
    Mitochondria generate ATP through cellular respiration.
  • What evidence supports the endosymbiotic origin of mitochondria and chloroplasts?
    They have their own DNA, double membranes, and reproduce independently within cells.
  • What are the three main fibers of the cytoskeleton?
    Microfilaments, intermediate filaments, and microtubules.
  • What is the fluid mosaic model of the plasma membrane?
    It describes the membrane as a fluid phospholipid bilayer with embedded proteins forming a mosaic.
  • What is diffusion?
    Diffusion is the passive movement of molecules from high to low concentration.
  • What is osmosis?
    Osmosis is the diffusion of water across a selectively permeable membrane.
  • How do animal cells respond to hypertonic solutions?
    They lose water and shrink (crenate).
  • What is the difference between simple diffusion and facilitated diffusion?
    Simple diffusion passes molecules directly through the membrane; facilitated diffusion uses transport proteins.
  • What is active transport?
    Active transport moves molecules against their concentration gradient using energy (ATP).
  • What is endocytosis?
    Endocytosis is the process of a cell engulfing material by forming vesicles from the plasma membrane.
  • What is ATP and its role in the cell?
    ATP is the energy currency of the cell, transferring energy through phosphorylation.
  • What is activation energy?
    Activation energy is the energy needed to start a chemical reaction.
  • How do enzymes speed up reactions?
    Enzymes lower activation energy without being consumed.
  • What is the induced fit model of enzyme action?
    The enzyme changes shape to fit the substrate more snugly during binding.
  • Write the overall chemical equation for cellular respiration.
    C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy (ATP).
  • Where does glycolysis occur in the cell?
    Glycolysis occurs in the cytoplasm.
  • What are the products of glycolysis?
    Two pyruvate molecules, 2 ATP (net), and 2 NADH.
  • Where does the citric acid cycle occur?
    In the mitochondrial matrix.
  • How many ATP are produced by oxidative phosphorylation per glucose?
    About 26 to 28 ATP molecules.
  • Why does lack of oxygen kill aerobic cells?
    Oxygen is the final electron acceptor in the electron transport chain; without it, ATP production stops.
  • What is fermentation?
    Fermentation is anaerobic energy harvesting that regenerates NAD+ for glycolysis.