Cells And Cellular Transport

Where does the name “cell” come from?  “Cells” were named by Englishman Robert Hooke in  He observed that cork wood looked like monk’s cells in a monastery.

The Cell: Those Who Discovered It Theodor Schwann: Stated that all animals were made of cells. Matthias Schleiden: Stated the all plants were made of cells. What a stretch, eh? Ruldolph Virchow: Stated that all cells come from pre- existing cells. Hmmm…isn’t that the chicken and the egg argument?

The Cell Theory 1.The cell is the basic unit of structure and function. 2.All organisms are made of one or more cells. 3.All cells come from pre-existing cells. Red blood cells Colonies of bacteria Plant cells showing chloroplasts

This is the human Herpes Virus! Exceptions to the Cell Theory 1.Viruses!! They have DNA and/or RNA inside a protein shell. They are capable of reproduction inside another living cell, but not on their own. 2.Mitochondria and chloroplasts have their own DNA and can reproduce inside a cell. 3.Obviously….the first cell.

Lysosome

Types of Cells Prokaryotic Cells  The first and most primitive cells  Lack a nucleus and other membrane bound organelles (mitochondria, etc) = Smallest cells!  ALL bacteria are prokaryotes. Eukaryotic Cells  Most organisms have eukaryotic cells (ex: all plant and animal cells!)  All genetic material is contained in a nucleus  Have many membrane bound organelles = larger cells!  Examples: ALL living things except bacteria!

The Cell Membrane Also called: The Phospholipid Bi-Layer or The Plasma Membrane A barrier that separates a cell from its surroundings. Cell membranes are “semi-permeable” because they allow some molecules to pass through, while others cannot.

Membrane Structure MOVIE! The lipid bilayer consists of two (bi) layers of phospholipids. The ____________ heads point to the outside and the ____________ tails point to the inside of the membrane. hydrophilic hydrophobic Various _________ molecules are embedded in the membrane as well. protein

Membrane Proteins 1. Marker Proteins: Like a “name tag” for the cell. Used in cell recognition together with carbohydrates. 2. Receptor Proteins: A messenger molecule binds to one side of the membrane protein and the message is sent to the other side (the messenger molecule is not.) 3. Enzymes: A protein catalyst can be embedded in the plasma membrane to facilitate chemical rxns of the cell.

Membrane Proteins Continued… 4. Channel Proteins: Trans-membrane proteins which allows specific molecules to pass from one side of the membrane to the other. Often transport LARGE molecules. YouTube - Cell membrane animation Watch it!!!

Cellular Transport The movement of molecules across the cellular membrane.

Cellular Transport Passive Transport  does NOT require cellular energy (ATP)  Moves molecules from high to low concentration Active Transport  DOES require ATP

Diffusion The movement molecules from an area of HIGH concentration to an area of LOW concentration. Molecules diffuse along, or down the concentration gradient until dynamic equilibrium is attained (equal conc. of molecules) oxygen, CO2, glucose, glycerol and other small molecules diffuse. This is a form of passive transport. (no ____ is needed) _________ molecules CANNOT diffuse across membranes, regardless of concentration gradient! LARGE ATP

Cellular Transport Passive Transport  does NOT require cellular energy (ATP)  Moves molecules from high to low concentration Examples - diffusion Active Transport  DOES require ATP

Osmosis Osmosis is the diffusion of _______ across a semi- permeable membrane. water This is passive transport, meaning _____ _______ is needed for it to occur. Water always moves from low to high SOLUTE concentration until equilibrium is established. This is osmosis! NO ATP Definition: SOLUTE – A substance that is dissolved in another substance. Examples: salt or sugar in water.

OSMOSIS…continued If a cell is placed in a solution with a LOWER concentration of solute, it will _________ (water will _________ the cell) If a cell is placed in a solution with a HIGHER concentration of solute, it will _________ (water will _________ the cell) enter swell shrivel leave

Cellular Transport Passive Transport  does NOT require cellular energy (ATP)  Moves molecules from high to low concentration Examples - diffusion - osmosis Active Transport  DOES require ATP

Moving Molecules Against the Concentration Gradient The sodium ions are more highly concentrated on the inside of the cell. With the help of ATP, the sodium ions are still pumped back into the cell (against the concentration gradient).

Cellular Transport Passive Transport  does NOT require cellular energy (ATP)  Moves molecules from high to low concentration Examples - diffusion - osmosis Active Transport  DOES require ATP  Moving molecules from low to high concentration

Phagocytosis This is “cell eating”. A cell engulfs (or wraps itself around) a food particle thus creating a food vacuole. This is a type of ACTIVE TRANSPORT!

Cellular Transport Passive Transport  does NOT require cellular energy (ATP)  Moves molecules from high to low concentration Examples - diffusion - osmosis Active Transport  DOES require ATP  Moving molecules from low to high concentration  Phagocytosis

Pinocytosis This is “cell drinking”. The cell membrane pinches inward (like a pin poking a hole) and creates a vacuole of dissolved particles. This is a type of ACTIVE TRANSPORT!

Cellular Transport Passive Transport  does NOT require cellular energy (ATP)  Moves molecules from high to low concentration Examples - diffusion - osmosis Active Transport  DOES require ATP  Moving molecules from low to high concentration  Phagocytosis  Pinocytosis

Membrane Proteins Using Cellular Energy

Cellular Transport Cellular Transport Passive Transport  does NOT require cellular energy (ATP)  Moves molecules from high to low concentration Examples - diffusion - osmosis Active Transport  DOES require ATP  Moving molecules from low to high concentration  Phagocytosis  Pinocytosis  Use of membrane proteins, carriers, receptors

Levels of Organization Atoms Molecules **Cells** Organelles Tissue ?? Cells with a similar structure and function.

Levels of Organization…Continued Organs Organ Systems Organism Can we keep going???