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Ch.4 A Tour of the Cell

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Termini in questo insieme (21)

  • Why are cells generally small?
    Cells are small to maintain a large surface area-to-volume ratio, which allows efficient exchange of nutrients and waste across the plasma membrane.
  • What is the surface area-to-volume ratio and why is it important?
    The surface area-to-volume ratio is the amount of surface area relative to the volume of a cell. Smaller cells have a higher ratio, enabling faster material exchange.
  • State the two main parts of cell theory.
    1. All living organisms are composed of cells. 2. All cells come from pre-existing cells.
  • Compare prokaryotic and eukaryotic cells.
    Prokaryotic cells lack a nucleus and membrane-bound organelles; eukaryotic cells have a nucleus and organelles.
  • What are the main differences between animal and plant cells?
    Plant cells have a cell wall, chloroplasts, and a large central vacuole; animal cells lack these but have centrioles.
  • Describe the structure and function of the nucleus.
    The nucleus is enclosed by a double membrane (nuclear envelope) with pores; it contains chromatin and nucleoli and stores genetic information.
  • What are ribosomes and their function?
    Ribosomes are complexes of RNA and protein that synthesize proteins, either free in cytoplasm or bound to rough ER.
  • List the components of the endomembrane system.
    Nuclear envelope, endoplasmic reticulum (rough and smooth), Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane.
  • What is the role of the rough endoplasmic reticulum (ER)?
    Rough ER is studded with ribosomes and synthesizes proteins, which are folded and packaged into transport vesicles.
  • What functions does the smooth endoplasmic reticulum perform?
    Smooth ER synthesizes lipids, detoxifies drugs and poisons, and metabolizes carbohydrates.
  • Describe the Golgi apparatus and its function.
    The Golgi apparatus is a stack of membrane sacs that modifies, sorts, and ships proteins and lipids received from the ER.
  • What are lysosomes and their function?
    Lysosomes are membrane-bound sacs containing digestive enzymes that break down food, waste, and damaged organelles.
  • What is the function of vacuoles in cells?
    Vacuoles store nutrients, waste, pigments, and help maintain water balance; central vacuoles are prominent in plant cells.
  • What is cellular respiration and which organelle performs it?
    Cellular respiration converts food energy into ATP; mitochondria perform this process.
  • Describe the structure of mitochondria.
    Mitochondria have a double membrane with inner folds called cristae and contain their own DNA and enzymes for respiration.
  • What is the function of chloroplasts?
    Chloroplasts conduct photosynthesis, converting solar energy into chemical energy stored in glucose.
  • Name the three types of cytoskeletal fibers and one function of each.
    Microtubules: shape and support, spindle fibers; Intermediate filaments: reinforce shape, anchor organelles; Microfilaments: cell movement, muscle contraction.
  • What are flagella and cilia composed of and their function?
    Both are made of microtubules and proteins; flagella propel cells, cilia move fluid or cells.
  • What is the extracellular matrix (ECM) in animal cells?
    The ECM is a network of proteins and carbohydrates outside the plasma membrane that supports cells and facilitates communication.
  • What is the plant cell wall made of and its function?
    Plant cell walls are made of cellulose and provide protection, structural support, and help maintain cell shape.
  • What are plasmodesmata in plant cells?
    Plasmodesmata are channels through cell walls that allow communication and transport of substances between plant cells.