Skip to main content
Back

Anatomy & Physiology: Cell Structure and Membrane Functions

Control buttons has been changed to "navigation" mode.
1/29
  • Basic functions shared by all cells

    Cell metabolism, transport of substances, communication, and cell reproduction.

  • Three basic components of most cells

    Plasma membrane, cytoplasm (cytosol, organelles, cytoskeleton), and nucleus.

  • Function of the plasma membrane

    Separates extracellular fluid (ECF) from intracellular fluid (ICF) and controls substance movement between compartments.

  • Phospholipid bilayer orientation in plasma membrane

    Hydrophilic phosphate heads face cytosol and ECF; hydrophobic fatty acid tails face inward.

  • Fluid mosaic model of the plasma membrane

    Membrane is a dynamic, fluid structure with components moving laterally within the phospholipid bilayer.

  • Types of membrane proteins

    Integral proteins (including transmembrane) and peripheral proteins on one membrane side.

  • Functions of membrane proteins

    Act as channels, carriers, enzymes, receptors, and provide structural support.

  • Selective permeability of the plasma membrane

    Allows some substances to pass while restricting others, maintaining internal environment.

  • Difference between passive and active transport

    Passive transport requires no ATP and moves substances down gradients; active transport requires ATP to move substances against gradients.

  • Simple diffusion

    Movement of solutes directly through the phospholipid bilayer down their concentration gradient.

  • Facilitated diffusion

    Movement of polar or ionic solutes across membrane via protein channels or carrier proteins without ATP.

  • Osmosis

    Passive movement of water across a selectively permeable membrane from low to high solute concentration.

  • Tonicity effects on cells

    Isotonic: no net water movement; hypertonic: water leaves cell; hypotonic: water enters cell.

  • Primary active transport

    Membrane protein uses ATP to pump solutes against their concentration gradient (e.g., sodium-potassium pump).

  • Secondary active transport

    Uses energy from a primary active transport-created gradient to move another solute against its gradient.

  • Membrane potential

    Charge separation across the membrane with positive charges in ECF and negative charges in cytosol

  • Vesicular transport

    Active transport involving membrane-enclosed vesicles to move large substances into or out of the cell.

  • Endocytosis types

    Phagocytosis: ingestion of large particles; pinocytosis: ingestion of dissolved substances; receptor-mediated endocytosis: ligand-specific uptake.

  • Exocytosis

    Process of releasing large substances from the cell by vesicle fusion with the plasma membrane.

  • Functions of the cytoskeleton

    Provides cell shape, mechanical support, moves organelles, divides the cell, and enables cell movement.

  • Types of cytoskeletal filaments

    Actin filaments (shape and movement), intermediate filaments (mechanical strength), microtubules (organelle positioning, cilia, flagella).

  • Specialized plasma membrane extensions

    Microvilli increase surface area; cilia move substances; flagella propel the cell.

  • Role of the nucleus

    Contains most DNA and controls cell functions.

  • Chromatin and chromosomes

    DNA in nucleoplasm as chromatin condenses into chromosomes during cell division; humans have 23 pairs.

  • Ribosomes

    Non-membrane organelles that synthesize proteins.

  • Rough vs Smooth Endoplasmic Reticulum

    Rough ER has ribosomes and modifies proteins; Smooth ER synthesizes lipids, stores calcium, detoxifies substances.

  • Golgi apparatus function

    Modifies, packages, and directs proteins for secretion, membrane insertion, or lysosome incorporation.

  • Lysosomes

    Contain digestive enzymes to break down substances and worn-out organelles.

  • Phases of the cell cycle

    Interphase (G1, S, G2 phases) and M phase (mitosis and cytokinesis).