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Anatomy & Physiology: Cell Structure, Transport, Protein Synthesis, and Cell Division

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  • What is the function of the centrosome and centrioles?

    The centrosome acts as a microtubule-organizing center and contains paired organelles called centrioles. Centrioles are small, barrel-shaped bodies oriented at right angles, consisting of nine microtubules arranged in a hollow tube. They organize the mitotic spindle during cell division.

  • Define diffusion and its driving force.

    Diffusion is the movement of solute molecules from an area of higher concentration to an area of lower concentration. The driving force is the concentration gradient, which provides potential energy for movement.

  • What is the difference between simple diffusion and facilitated diffusion?

    Simple diffusion involves nonpolar solutes and gases passing directly through the phospholipid bilayer. Facilitated diffusion involves charged or polar solutes crossing the membrane via channel or carrier proteins.

  • What are integral and peripheral membrane proteins?

    Integral proteins span the entire membrane and are involved in transport, signaling, and adhesion. Peripheral proteins are loosely attached to the membrane surface and assist in signaling, structural support, and maintaining cell shape.

  • Explain osmosis in terms of solvent movement.

    Osmosis is the movement of solvent (water) across a selectively permeable membrane from a solution with lower solute concentration to one with higher solute concentration.

  • What are aquaporins?

    Aquaporins are specialized water channels in the plasma membrane that facilitate the rapid movement of water molecules during osmosis.

  • Define tonicity and its types.

    Tonicity compares solute concentrations of two solutions and their ability to cause osmosis. Types: Hypertonic (ECF has higher solute, cell shrinks), Isotonic (equal solute, no net water movement), Hypotonic (ECF has lower solute, cell swells).

  • What is the sodium-potassium pump and its role?

    The Na+/K+ pump is a primary active transport pump that moves 3 sodium ions out and 2 potassium ions into the cell against their concentration gradients using ATP, maintaining essential ion gradients.

  • Describe secondary active transport.

    Secondary active transport uses the potential energy from a concentration gradient created by primary active transport to move another substance against its gradient, often coupling passive and active transport.

  • What is electrophysiology in the context of cell membranes?

    Electrophysiology studies the electrical potential (membrane potential) caused by charge differences across the plasma membrane, with the inside of the cell being more negative than the extracellular fluid.

  • What are the main types of vesicular transport?

    Vesicular transport includes endocytosis (phagocytosis, pinocytosis, receptor-mediated) to bring substances into the cell, and exocytosis to move substances out of the cell, all requiring ATP.

  • Explain phagocytosis and which cells perform it.

    Phagocytosis is the process of engulfing large particles like bacteria or dead cells, performed by specialized immune cells called phagocytes.

  • What is receptor-mediated endocytosis?

    A type of pinocytosis where ligands bind to specific receptors in protein-coated pits, resulting in vesicles with high concentrations of a specific substance being brought into the cell.

  • Outline the two main steps of protein synthesis.

    Protein synthesis involves transcription (DNA code copied to mRNA in the nucleus) and translation (mRNA decoded by ribosomes in the cytoplasm to form a polypeptide chain).

  • What is the role of RNA polymerase in transcription?

    RNA polymerase binds to the DNA promoter, unwinds DNA, and synthesizes a complementary mRNA strand by linking RNA nucleotides during transcription.

  • Describe the process of translation initiation.

    Translation begins when an initiator tRNA binds the mRNA start codon at the ribosome, setting the stage for polypeptide synthesis.

  • What is the function of tRNA during translation?

    tRNA carries specific amino acids and has an anticodon complementary to mRNA codons, delivering amino acids to the ribosome to build the polypeptide chain.

  • What happens during posttranslational modification?

    After translation, polypeptides fold and undergo structural changes to become functional proteins, sometimes requiring assistance from other proteins or organelles.

  • Define the cell cycle and its main phases.

    The cell cycle is the ordered series of events from cell formation to division, including interphase (G1, S, G2 phases) and M phase (mitosis and cytokinesis).

  • What occurs during the S phase of interphase?

    During the S phase, DNA synthesis occurs where chromatin unwinds and each DNA strand is duplicated by semiconservative replication.

  • List the four stages of mitosis and a key event in each.

    Prophase: Chromatin condenses, spindle forms.
    Metaphase: Chromosomes align at cell equator.
    Anaphase: Sister chromatids separate.
    Telophase: Nuclear envelope reforms, chromosomes decondense.

  • What is cytokinesis?

    Cytokinesis is the division of the cell's cytoplasm and organelles, completing cell division by physically separating the two daughter cells.