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Cells: The Living Units - Anatomy & Physiology

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Terms in this set (30)

  • What are the three major regions of a generalized human cell?

    The nucleus (DNA-containing control center), cytoplasm (intracellular fluid with organelles), and plasma membrane (flexible outer boundary).

  • What is the principle of complementarity in cells?

    The biochemical activity of cells reflects the operation of their organelles.

  • What substances are considered extracellular materials?

    Extracellular fluids (interstitial fluid, blood plasma, cerebrospinal fluid), cellular secretions (saliva, mucus), and extracellular matrix.

  • Describe the fluid mosaic model of the plasma membrane.

    A moving bilayer of phospholipids and cholesterol with embedded proteins that allow selective permeability and communication.

  • What are the roles of phospholipids in the plasma membrane?

    Phospholipids have polar hydrophilic heads facing water and nonpolar hydrophobic tails facing inward, forming a bilayer that acts as a barrier.

  • What functions do membrane proteins perform?

    Transport, enzymatic activity, receptors for signal transduction, cell-cell recognition, cell-to-cell joining, and attachment to cytoskeleton and extracellular matrix.

  • What is the glycocalyx and its function?

    Sugar coating on the cell surface formed by glycoproteins and glycolipids; acts as biological markers for cell recognition and immune system identification.

  • Name the three types of intercellular junctions and their functions.

    Tight junctions (impermeable seals), desmosomes (mechanical coupling), and gap junctions (allow communication and ion passage).

  • What is diffusion and what factors affect its rate?

    Movement of molecules down a concentration gradient; faster with greater concentration difference, smaller molecules, and higher temperature.

  • How does facilitated diffusion differ from simple diffusion?

    Facilitated diffusion requires carrier or channel proteins to move specific solutes down their concentration gradient; it is saturable and specific.

  • Explain osmosis and its driving force.

    Net movement of water through a selectively permeable membrane from low to high solute concentration, often via aquaporins.

  • Define isotonic, hypertonic, and hypotonic solutions in relation to cells.

    Isotonic: no net water movement; hypertonic: water leaves cell causing shrinkage; hypotonic: water enters cell causing swelling or lysis.

  • What is primary active transport and give an example?

    Transport using ATP to move substances against their gradient; example is the Na+-K+ pump moving 3 Na+ out and 2 K+ in per ATP.

  • Describe secondary active transport.

    Uses energy from ion gradients created by primary active transport to move other substances against their gradient via symporters or antiporters.

  • What are the three types of endocytosis?

    Phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis (selective uptake via receptors).

  • What is exocytosis and its purpose?

    Process of ejecting substances from the cell via secretory vesicles that fuse with the plasma membrane; used for hormones, neurotransmitters, and wastes.

  • What generates the resting membrane potential (RMP) in cells?

    Concentration gradients and membrane permeability, especially K+ leaking out and Na+ leaking in, maintained by the Na+-K+ pump.

  • What are cell adhesion molecules (CAMs) and their functions?

    Proteins on cell surfaces that anchor cells to each other and the extracellular matrix, assist cell movement, attract WBCs, and transmit signals.

  • What are the main components of the cytoplasm?

    Cytosol (fluid), inclusions (nutrient stores, pigments), and organelles (membranous and nonmembranous).

  • What is the function of mitochondria?

    Produce most of the cell's ATP through aerobic cellular respiration; have a double membrane with cristae and their own DNA.

  • What is the difference between rough and smooth endoplasmic reticulum?

    Rough ER has ribosomes and synthesizes proteins; smooth ER synthesizes lipids, detoxifies chemicals, and stores calcium.

  • What is the role of the Golgi apparatus?

    Modifies, sorts, and packages proteins and lipids from the rough ER for secretion, membrane insertion, or lysosome formation.

  • What are lysosomes and their function?

    Membranous sacs with digestive enzymes that break down bacteria, viruses, worn organelles, and release calcium from bone.

  • What are peroxisomes and their role?

    Contain oxidase and catalase enzymes that detoxify harmful substances and free radicals by converting them to hydrogen peroxide and then water.

  • What are the three types of cytoskeletal elements and their functions?

    Microfilaments (cell shape and motility), intermediate filaments (mechanical support), microtubules (organelle movement and cell shape).

  • What is the function of cilia and flagella?

    Cilia move substances across the cell surface; flagella propel the entire cell (e.g., sperm cell).

  • What is the nucleus and its main components?

    Control center of the cell containing DNA; surrounded by nuclear envelope with pores; contains nucleoli for ribosome synthesis.

  • What are the phases of the cell cycle?

    Interphase (G1, S, G2 phases for growth and DNA replication) and mitotic phase (mitosis and cytokinesis for cell division).

  • What are the steps of protein synthesis?

    Transcription (DNA to mRNA in nucleus) and translation (mRNA to polypeptide at ribosomes in cytoplasm).

  • What is apoptosis?

    Programmed cell death that removes damaged or unnecessary cells via caspase activation and phagocytosis.