Cell structures and their functions

• Organelles: specialized structures in cells that perform

  specific functions
• Cytoplasm: jelly-like substance that holds organelles
• Cell Membrane: controls what goes in and out of the cell, controls what goes on inside the cell, outermost component of a cell
• Extracellular: material outside cell
• Intracellular: material inside cell
• Cell Membrane also called Fluid Mosaic Model
• Phospholipids form a double layer or bilayer
• Phospholipids contain 2 regions: polar and nonpolar
• Polar regions:

  “heads”

  hydrophilic (H2O loving)

  • exposed to H2O
• Nonpolar regions:

  “tails”

  hydrophobic (H2O fearing)

  • away from H2O
• Enzymes, glycogen, and potassium are found in

  higher concentrations INSIDE the cell.
• Sodium, calcium, and chloride are found in higher

  concentrations OUTSIDE the cell.
• diffusion: the movement of molecules from an area of high concentration to an area of low concentration
• Membrane channels: open and close to allow ions and water to pass through, proteins that extend from one side of cell

  membrane to other.
• Carrier molecules: bind to molecules, transport them across, and

  drop them off
• Vesicles:

  can transport a variety of materials

  • fuse with cell membrane
• Solution: solid, liquid, or gas that contains one or more solutes
• Solute: substance added to solvent that dissolves
• Solvent: substance such as H2O that solute is being added to
• Concentration gradient:

  • measures conc. difference at 2 points
  • greater the distance the faster the solute will travel
• Filtration: movement of fluid through a partition with holes
• Facilitated diffusion:

  diffusion with aid of a carrier molecule

  • requires no ATP
• Active transport:

  moves substances from low to high conc.

  requires ATP

  • Ex. Sodium-potassium pump
• Osmosis: diffusion of water across a cell membrane
• Osmotic pressure: force required to prevent movement of water across cell membrane
• Hypotonic solution:

  • lower conc. of solutes outside cell
  • higher conc. of H2O outside cell
  • H2O moves into cell
  • lysis (burst)
• Hypertonic solution:

  • higher conc. of solutes outside cell
  • higher conc. H2O inside cell
  • H2O moves out
  • crenation (shrinks)
• Isotonic solution:

  • equal conc. of solutes
  • water doesn’t move
  • cell remains intact
• Endocytosis: process that brings materials into cell using vesicles
• Phagocytosis: cell eating (solid particles)
• Pinocytosis: cell drinking (liquid particles)
• Exocytosis: process that carries materials out of cell using vesicles
• Cytoplasm

  • Location: inside cell
  • Characteristic: jelly-like fluid
  • Function: give cell shape and hold organelles in place
• Nucleus

  • Location: center of cell
  • Characteristic: all cells contain nucleus at some point

  Function: houses DNA
• Nuclear envelope:

  Location: edge of nucleus
• Nuclear pores:

  • Location: surface of nucleus
  • Function: where materials pass in and out of nucleus
• Chromosome:

  Location: inside nucleus

  Characteristic: made of DNA and proteins

  Function: part of genetic makeup
• Chromatin:

  Location: inside nucleus

  Characteristic: loosely coiled chromosomes
• Nucleolus

  Location: in nucleus

  Function: produce ribosomes
• Ribosome

  Location: attached to RER or cytoplasm

  Function: produce proteins