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Cell Structure and Membrane Transport Study Guide -- Chapters 4 and 5
CELL STRUCTURE AND FUNCTION (Chapter 4)
Cell Theory: Know the three parts of the theory.
Prokaryotic vs. Eukaryotic Cells: Bacteria are prokaryotic, do not have nucleus or other membranebound organelles. Do have cell membrane and ribosomes.
Importance of Surface Area: Limits how much can enter or leave the cell. Ratio of surface area to
volume goes down as the cell gets bigger, and puts limit on size of cell.
Fluid Mosaic Model: Cell membrane is phospholipid bilayer with proteins embedded in it or attached
to it. The proteins are free to move around in the bilayer, it is fluid, not fixed.
Multi-Cellular Organization: Cells organized into tissues, tissues into organs and organ systems.
Tissue types- epithelial, muscle, connective and nervous.
Animal organ systems include respiratory, digestive, nervous and other systems. Plant organs
include leaves, root, stem and flower
Eukaryotic Cell Organelles:
Nucleus – large, central, surrounded by double membrane “envelope,” holds the DNA.
Nucleolus – area within nucleus where ribosomes are made.
All the rest of the Organelles are found in the Cytoplasm, the semi-liquid filler substance.
Mitochondria – ATP generation, have own DNA.
Ribosomes – small, made of RNA + protein, made in nucleolus, job is protein synthesis.
Endoplasmic Reticulum – network of membrane-lined channels inside cell for transport.
Golgi Apparatus – System of membranes that packages cell proteins into vesicles for export.
Lysosomes – membrane-lined vesicles with digestive enzymes.
Microfilaments/Microtubules – forms “cytoskeleton” for support and organelle movement.
Cilia & Flagella – extensions from the cell membrane, made of many pairs of microtubules.
Centriole (Animal Cells only) – forms network of filaments for cell division.
Plant-specific organelles include: Cell Wall, Central Vacuole, Plastids (include chloroplast).
HOMEOSTASIS AND TRANSPORT ACROSS THE MEMBRANE (Chapter 5)
Passive Transport: Cell does not use any ATP for passive transport. Includes ion channels.
Vocabulary – hypertonic, hypotonic, isotonic, diffusion, osmosis, concentration gradient, equilibrium.
Most plants live in hypotonic environment, needed to maintain Turgor Pressure. Hypertonic
solutions cause Plasmolysis (wilting) in plants, and 2dehydration in animals.
Osmosis – diffusion of water across a semi-permeable membrane. Direction of water movement is
from a hypotonic to a hypertonic solution.
Facilitated Diffusion – carrier proteins assist movement of glucose across the membrane.
Active Transport: Movement across membrane from low to high concentration – requires energy use
by the cell.
Sodium/Potassium Pump – moves potassium into and sodium out of the cell against the concentration
gradient. Uses energy from 1 ATP for each pump cycle.
Endocytosis, Exocytosis – involve bulk passage through the cell membrane in membrane-bound
vesicles.