Cell Biology
History – Timeline
 1500’s 1st Lenses
 Originally used to determine the quality of cloth
 1600’s
 Telescope/microscope – used a combination of lenses
History – Timeline
 1665 – Robert Hooke
 Published drawings of cork using the 1st Light Microscope
 Coined the word “cell”
 Cork cells looked like little rooms, which were called cells in his time
History – Timeline
 1674 – Anton van Leeuwenhoek
 Used Microscopes to study nature
 Studied pond water
History – Timeline
 1838 – Matthias Schleiden
 Plants are made up of cells
History – Timeline
 1839 – Theodor Schwann
 Animals are made up of cells
History – Timeline
 1855 – Rudolph Virchow
 Studied cell reproduction
 This is where the Cell Theory came from.
Cell Theory
 All living things are composed of cells
 Cells are the basic units of structure and function in living
things
 New cells are produced from existing cells
Rudolph Virchow
History – Timeline
 1931 – Janet Plowe
 Cell membrane is an actual structure – not just “space” between
two liquids
Basic Cell Structures
 Cell Membrane
 Thin, flexible
 Support and protect cell
 ALL cells!!!
Basic Cell Structures
 Cell Wall
 Strong, Rigid
 Support and protect cell
Cell Wall (Continued)
 Plants, algae, fungi and almost all prokaryotes
 Found OUTSIDE the cell membrane
 Allows for water, oxygen, CO2 to pass through
 Consists of Carbohydrates and protein
 Plant cells = cellulose (tough carbohydrate fiber)
 Primary component of both wood and paper!!!
Basic Cell Structures
 Nucleus (Plural: Nuclei)
 “Brain”
 Controls cell activities
 Contains genetic material
 1st Discovered by Robert Brown – 1831
Nucleus (Continued)
 Includes hereditary (genetic) information
 DNA – coded instructions for making proteins
 Chromatin – granular and visible – spread out
 Chromosomes – CONDENSED chromatin, ready for cell
division
Basic Cell Structures
 Cytoplasm
 Material inside the cell (Does NOT include the nucleus)
 Other organelles found in the cytoplasm
 Organelles = “Little Organs”
Different Types of Cells
Prokaryotic Cells
(Bacteria)
Eukaryotic Cells
(Animal and Plant)
No Nucleus
Have a nucleus
Generally Small/Simple
Have organelles (“Little Organs”)
All Bacteria
Most have cell walls
Only plant cells have cell walls.
Nucleolus
 Small, dense region INSIDE the nucleus
 Where the assembly of ribosomes begin
 Ribosomes – aide in the production of proteins.
Nuclear Envelope
 Also known as the Nuclear membrane
 Bilayer – 2-layer membrane surrounding the nucleus
 Pores – 1000’s of them! (little holes)
 RNA constantly going through
Cytoskeleton
 “Backbone” to a human
 “Frame” to a house
 Matrix of Support
 “Cyto” = cell, “skeleton” = supporting structure
 Helps the cell maintain its shape
 Helps move organelles within the cell.
Microtubules
 Part of the Cytoskeleton
 Hollow tubes of proteins (larger than microfilaments)
 Inside the cell
 Serve as “tracks” for the organelles to move on.
 Like a roller coaster track that the car sits on and moves across.
 Outside the cell
Paramecium
 Movement of the cell
 Cilia
 Small hair-like projections
 Flagella
 Large projection(s)
E. Coli
Sperm
Microfilaments
 Long, thin fibers
Ribosomes
 Small and Round
 Mostly attached to Rough Endoplasmic Reticulum
 Some are found “Free” in the cell.
 Proteins assembled here using “Code” that comes from the
nucleus.
 RNA (Ribonucleic Acid)
Endoplasmic Reticulum (ER)
 Components of the cell membrane are assembled here.
 Rough ER
 Studded with Ribosomes
 This is what gives it the “Rough” appearance.
 Some proteins are modified here
 Smooth ER
 Contains enzymes that do specific tasks.
Golgi Apparatus
 Attaches carbohydrates and lipids to proteins
 The proteins that come from the Rough ER
 Looks a lot like the Smooth ER
Lysosomes
 “Garbage Disposals”, “Pac-Mans”
 Small
 Filled with enzymes
 Break down lipids, carbohydrates and proteins from food
 Can be used by the rest of the cell.
 Break down organelles and debris that would just fill up the
cell
Vacuoles
 “Storage units”
 Store materials
 Plants have one LARGE Vacuole
 Pressure for supporting heavy leaves/flowers
 Ever seen a plant that hasn’t been watered lately?
 Droopy/Wilted.
 Animals – smaller form – vessicles
 Typically used for transporting substances in and out of the cell
 *we will learn more about these a little later in class.
Chloroplasts
 Found MOSTLY in plants
 Also found in some other organisms – NOT animal or fungal
cells
 Photosynthesis occurs here
 Conversion of sunlight into usable energy for the cell.
Mitochondria
 “Powerhouse” of the cell
 Convert food energy to high-power energy for use by the cell
 Grow, develop, move
 Found in just about all Eukaryotic cells
 ie – No bacteria!
Demonstration What is the purpose of a cell membrane?
 Set-up
 Iodine and Water
 Starch and Water
 Iodine and Starch
 Membrane (baggie) with Twist tie
 What will happen?
Cell Membrane
 Regulates in/out of cell
 In: Food and Water and . . .
 Out: Waste and. . .
 Lipid bilayer (“bi” = 2 , “layer”)
 Proteins that go through the layers
 Carbohydrates attached to the proteins on the outside of the
cell
 These are “Markers” – it is how the cell is recognized.
 Can substances and water move through this membrane?
What do you think?
Terms:
 Solution: Liquid mixture of 2 or more substances – Evenly
mixed
 Solute: Item being dissolved into the liquid (solvent)
 Typically smaller amount than the solvent.
 Concentration: Amount of solutes in an amount (volume)
of solution.
 Example: Salt Water
 Everything wants to be equal
Diffusion
 Works the same way!
 Solutes move from an area of High Concentration to an area
of low concentration until Equilibrium is reached.
 Equilibrium = “Equal”
 Does NOT require energy!
 If the substance (the solute) can’t cross the membrane, then
what?
 We say the membrane is not permeable to that substance
(solute)
 But…. What happens?
 Nothing?
 Something?
Osmosis
 Osmosis: Diffusion of water across the membrane
 Water will move from the area of high concentration (of
water) to the area of low concentration (of water) till
equilibrium is reached. Requires No energy!
 Solution is Isotonic (Same Strength)
Hypertonic solution
 “Hyper” = More or Above
 “Hyperactive” = Lots of activity, extra energy
 More solutes = More concentrated solution
 If the environment outside
of the cell is Hypertonic,
what will happen?
-Water flows out of cell
- Cell shrinks.
Hypotonic solution
 “Hypo” = Less or Below
 “Hypoglycemic” = Low blood sugar
 Less solutes = Less concentrated solution
 If the environment outside
of the cell is Hypotonic,
what will happen?
-Water flows into the cell
- Cell gets bigger.
Isotonic solution
 “Iso” = Same, Equal
 “Isometric” = Equal measurements
 Same amount of solutes = Same concentrations
 If the environment outside
of the cell is Isotonic,
what will happen?
- Water flows into and out of
the cell
- The cell stays the same
size
Osmotic Pressure
 Pressure exerted on a membrane by water
 Most cells are Hypertonic (inside)
 So what would happen when the cell would come in contact
with fresh water?
Just like this
water balloon –
it will burst!
So. . . .
 What about our blood?
 Our blood is Isotonic!
 How do cell walls help a plant?
 Don’t they come in contact with fresh water all the time?
Hyper
Iso
Hypo
So, what are the solutions outside
the cell?
 A.) Hypertonic (Outside the cell)
 B.) Hypotonic (Outside the cell)
Review
(Occurring across the Lipid Bilayer)
 Diffusion
 Movement of solutes across a membrane
 Requires No Energy
 Osmosis
 Movement of water across a membrane
 Requires No Energy
 Hypertonic
 High amount of Solutes (High Concentration of Solutes)
 Hypotonic
 Low amount of Solutes (Low Concentration of Solutes)
 Isotonic
 Equal amounts of Solutes (at Equilibrium)
Facilitated Diffusion
 Items that can not move across the membrane (lipid bilayer)
can use SPECIALIZED channels to move across the
membrane
 Examples: Glucose, sugars, salts, ions
 Specific Proteins are the Specialized channels.
 Fast, Specific
 Responds to concentrations
 Move from an area of high concentration to an area of low concentration.
 Requires NO energy!
Active Transport
 Movement of items against concentrations
 Move from an area of low concentration to an area of high
concentration.
 Uses ENERGY!!!!
 Compare to a pump
 Na+ out, K+ in
 Inside the cell, low Na+, and high K+
More Ways to Move materials:
 Exocytosis
 Removal of substances from the cell by vesicles that then fuse
with the cell membrane to release items from the cell.
Endocytosis
 Taking materials in by creating vesicles around them.
 Two Types of Endocytosis:
 Phagocytosis – clumps of food, large molecules, whole
cells that need to be broken down by the cell
 “Phago” = devour, “cyto” = cell, “osis” = process of
 Requires lots of energy!
 Pinocytosis – small particles/fluids, already broken down
molecules
Review
 “Cyto”
 Cell
 “Exo”
 Out
 “Endo”
 In
 “Osis”
 Process of
 “Phago”
 Devour
Unicellular Organism
 One Celled
 They grow, respond, reproduce
 Example:Yeast
 Both Prokaryotes and Eukaryotes
 Prokaryote: Bacteria
 Eukaryote: Algae and Yeast (fungi)
Paramesium
Protists
Multicellular Organism
 Many Cells
 Interdependent cells
 Each has a specialized function that depends on another
 Example: Football or Baseball team
 Each player dependent on another player to do their job
 Move, react, respond, produce substances
 Example: Humans
 We have nerve cells, muscle cells, blood cells, skin (epithelial)
cells, pancreatic cells (enzymes that digest food)
Levels of Organization
 Cells
 Basic
 Division of labor (Specialization)
 Tissues
 Group of similar cells, perform a specific function
 Muscle tissue, nerve tissue, epithelial (skin) tissue, connective tissue (bone,
blood, cartilage, lymph)
 Organs
 Groups of tissues working together
 Example: A Muscle has nerve and connective tissue running through the
muscle tissues
 Organ Systems
 Group of organs that work together to do/complete a specific task
 11 Major groups (Page 892)