Where does the name “cell” come from?
• “Cells” were named by Englishman Robert Hooke in 1665.
• He observed that cork wood looked like monk’s cells in a monastery.
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.
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.
Levels of Organization…ContinuedOrgans
Organ Systems
Organism
Types of CellsProkaryotic Cells• The first and most
primitive cells
• Lack a nucleus and other membrane bound organelles (mitochondria, etc)
• Bacteria are the ONLY 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
Cell Organelle FunctionsCell Membrane: provides a barrier between the cell
and the environment.Vacuole: stores water, minerals and sometimes
food.Lysosome: a sac of digestive juices (acts like a
stomach).Mitochondria: where cellular respiration takes
place, our energy comes from here!Golgi Bodies: “packages” cell material, wraps a
membrane around protiens and materials made in the cells.
Cell Organelle FunctionsCentrioles: (ONLY in animal cells) help the cell
undergo cellular division, or mitosis.Cytoplasm: jelly like material that fills in the extra
space in a cell, also where most of our chemical rxns occur.
Ribosomes: site of protein production.Endoplasmic Reticulum (ER): Transports materials
around the cell.Nuclear Membrane: separates the nucleus from the
rest of the cell.
Cell Organelle Functions
Nucleolus: dense part of a nucleus, where RNA is made.
Nucleus: stores DNA, controls most cellular activities.
Cell Wall: rigid structure around the outside of plant cells to give them structure and support.
Chloroplast: site of photosynthesis, makes sugar molecules using sunlight, water and carbon dioxide.
The Cell Membrane
Also called:
The Lipid Bi-Layer, Fluid Mosaic Model,
And
The Plasma Membrane
Cell membranes are “semi-permeable” because they allow some molecules to pass
through, while others cannot.
A barrier that separates a cell from its surroundings.
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.
Various _________ molecules are embedded in the membrane as well
Membrane Facts!
hydrophilichydrophobic
proteins
Cell Membrane Cross Section
This is the Lipid Bilayer. Why does this name fit?
This is one of many kinds on proteins embedded in the membrane.
Membrane Proteins
Continued…Channel Proteins: These proteins reach through the membrane to both sides. It allows specific molecules to pass from one side of the membrane to the other.
YouTube - Cell membrane animation
Transport Proteins: Proteins that physically move molecules across the membrane. There are a variety of types!
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 of molecules from an area of HIGH concentration to an area of LOW concentration.
The direction of diffusion is called the concentration gradient.
This is a form of passive transport.
_________ molecules CANNOT diffuse, regardless of concentration gradient!
LARGE
What types of molecules can NOT diffuse??
Even though all molecules seem small to us, they do vary in size a lot!
Large molecules can NOT cross the cell membrane!
Large molecules must rely on active transport.
Cellular Transport
• Passive Transport does NOT require cellular energy (ATP)
• Moves molecules from high to low concentration
Examples:• Diffusion
• Active Transport DOES require ATP
OsmosisOsmosis is a special name for the diffusion of ________ across a semi-permeable membrane.
Because this requires NO ATP, it is called _____________.
WATER
Passive transport
Water always moves from low to high SOLUTE
concentration. This is osmosis!
•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)
swellenter
shrivelleave
Cellular Transport
• Passive Transport does NOT require cellular engery (ATP)
• Moves molecules from high to low concentration
Examples:• Diffusion• Osmosis
• Active Transport DOES require ATP
PhagocytosisThis 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!
Clip
Cellular Transport
• Passive Transport does NOT require cellular engery (ATP)
• Moves molecules from high to low concentration
Examples:• Diffusion• Osmosis
• Active Transport DOES require ATP
Examples:• Phagocytosis
PinocytosisThis 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!
Clip
Cellular Transport
• Passive Transport does NOT require cellular engery (ATP)
• Moves molecules from high to low concentration
Examples:• Diffusion• Osmosis
• Active Transport DOES require ATP
Examples:• Phagocytosis• Pinocytosis
Membrane Proteins Using Cellular Energy: The proteins we learned about in the membrane
sometimes require energy!
Cellular Transport
• Passive Transport does NOT require cellular energy (ATP)
Examples:• Diffusion• Facilitated Diffusion• Osmosis
• Active Transport DOES require ATP
Examples:• Phagocytosis• Pinocytosis• Use of membrane
proteins (ex: transport proteins)
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).
This is like moving against the flow of traffic!
It takes ENERGY!
Cellular Transport
• Passive Transport does NOT require cellular energy ATP)
Examples:• Diffusion• Facilitated Diffusion• Osmosis
• Active Transport DOES require ATP
Examples:
• Phagocytosis
• Pinocytosis
• Use of membrane proteins (carrier proteins, etc)
• Moving molecules from low to high concentration