Presentation on theme: "The Cell Microscopes, History & the Cell Theory. The Microscope ► Originally created for trade purposes ► Merchants needed a way of examining types of."— Presentation transcript:
The Microscope ► Originally created for trade purposes ► Merchants needed a way of examining types of fibers more closely (i.e., silk, wool, etc) to ensure quality of the product
Anton van Leeunwenhoek ► Dutch biologist ► Generally credited w/developing first microscope (early to mid 1600’s) ► Studied never-before-seen living organisms in pond water, blood cells and bacteria ► Called what he saw “animalcules” and “beasties”
Robert Hooke ► English scientist ► Examined cork slices and other plant tissues under a microscope ► What he saw were the remnants of dead cells ► He saw box-like structures he called ‘cells’ ► Named them after the rooms in a monastery lived in
The Happenin’ 1800’s ► 1824-French scientist Henry Dutrochet says all living things are made of cells ► 1831-Scottish scientist Robert Brown calls the dense round body in the middle of a cell the “nucleus” ► Didn’t know the function of the nucleus
The Happenin’ 1800’s: The Big Three ► 1838-German botanist Matthias Schleiden says all plants are made of cells ► 1839-Zoologist Theodor Schwann says all animals are made of cells ► 1855-German Physician Rudolf Virchow says that all cells arise from pre-existing cells ► These guys helped to form the “Cell Theory”
The Cell Theory: The modern Version ► 1. All organisms are made up of cells. ► 2. New cells are always produced from pre- existing cells. ► 3. The cell is a structural and functional unit of all living things. ► 4. The cell contains hereditary information which is passed on from cell to cell during cell division. ► 5. All cells are basically the same in chemical composition and metabolic activities
The Cell Structure Types of Cells, Examples and Organelles
Cell Size Limitations: Think “The Roman Empire” ► Cell size is limited by the: ► The flow of information and materials through the cell ► The cell on the right takes 5 times as long to get info from nucleus to membrane!
Two Types of Cells ► Two major categories of cells based upon nuclei Eukaryotic Cells (Eukaryotes) ► Have a nucleus and membrane-bound organelles Prokaryotic Cells (Prokaryotes) ► Do NOT have a nucleus ► No internal membrane-bound organelles
Prokaryotic Organisms Comprise the Kingdom Monera ► Monera include all of the bacteria ► The simple structure of bacteria, and prokaryotic cells in general, make them the most numerous of all the kingdoms
Basic Cell Structure Basic Cell Structure ► Three common organelles (little organs) to all Plant and Animal cells: ► Cell Membrane ► Nucleus ► Cytoplasm
Cell Membrane ► Present in all cells ► The outer boundary of the cell ► Regulates what enters and exits the cell ► Provides protection and support ► REAL WORLD EXAMPLE: A chain link fence around a city
Cell Membrane Structure ► Lipid Bilayer (Composed of Phospholipids- a type of fat) ► Proteins imbedded in the bilayer provide: ► Support ► Channels for molecular transit ► Pumping action for transit ► Carbohydrates on cell surface act as chemical identification for the body
Cell Membrane Junctions ► Gap Junctions Communication ► Tight Junctions Impermeable ► Desmosomes Anchoring
Nucleus ► The control center of the cell ► Not all cells have nuclei “true” nuclei (think of prokaryotes-i.e., bacteria!) ► The most important part of the nucleus is the DNA inside of it The genetic blueprint of life
Nucleus Structure ► The Nuclear Envelope (also nuclear membrane) ► Two membranes closely held together ► Nuclear pores allow transit in and out of the envelope ► Real world example: Security checkpoints at City Hall
Nucleus Structure ► Nucleolus Consists of the Ribonucleic Acid (RNA) and protein Ribosomes are made here ► Chromosomes Elaborate protein “frame” that holds and protects DNA
Cytoplasm ► Gel/water-like material between the nucleus and the cell membrane ► Holds all the organelles in place ► Provides a place for chemical reactions to take place
Cell Wall ► Found in plants, algae and some bacteria ► Lies outside the cell membrane ► Provides protection and incredible support ► Very porous (lots of holes!) for important molecules to pass through ► Made of multiple layers of different types of carbohydrates including Cellulose-otherwise known as fiber
Mitochondria ► Power station (animal cell) ► Takes chemical energy stored in food and converts it to a form the body can use-ATP ► Contains two membranes: ► Outer membrane surrounds and protects ► Inner membrane folds to increase surface area energy conversion happens here
Chloroplasts ► Power station (plant and algae cell) ► Captures light energy from the sun (using chlorophyll) and converts it into chemical energy ► The innermost membrane captures the light energy from the sun
Plastids ► Plant organelles w/many forms ► Chloroplasts are one form ► Stores food and pigments ► Leukoplasts Store food ► Chromoplasts Store pigments (coloration)
Ribosomes ► Makes proteins from amino acids ► Cells that need more protein will have significantly more ribosomes (e.g., muscle cells will have more than skin cells) ► Composed of RNA and proteins ► Membrane-bound or free-floating ► Among the smallest of the organelles
Endoplasmic Reticulum (ER) ► Complex network of channels throughout a cell ► Acts as an superhighway within the cell for transport of materials ► Two types of Endoplasmic Reticulum ► Smooth ► Rough
Smooth Endoplasmic Reticulum ► Have a smooth appearance (do not have ribosomes attached to them) ► Some cells’ ER hold special enzymes and chemicals for various functions
Rough Endoplasmic Reticulum ► Rough due to ribosomes being stuck to the outside ► Involved in making proteins ► New proteins are inserted into Rough ER for transport through the cell
Golgi Apparatus ► Discovered by Italian scientist Camillo Golgi ► Resembles a flattened stack of membranes on top of one another ► Located by the cell membrane ► Assists in the collection, modification, packaging and distribution of proteins and other molecules throughout the cell ► The UPS-United Parcel Service of the cell
Lysosomes ► The “Cleanup Crew” of the cell ► Small, they contain chemicals and enzymes for digestion ► Involved in cleaning up cell parts, molecules, etc. that have died or outlived their usefulness ► Formed by the Golgi Apparatus ► Also called the “Suicide Sac”
Lysosomes ► Conducts the process of endocytosis ► Engulfing of large particles too big to fit through a cell membrane
Vacuoles ► Saclike structure that: Stores water, salts, proteins and carbohydrates ► Found in plant and animal cells ► Vacuole is much larger in plants due to enormous amounts of water being stored ► Builds up water pressure and makes plants sturdy
Cytoskeleton ► Cell framework ► Composed of filaments and fibers that help maintain shape, aide in transport, etc. ► Composed of two parts: ► Microtubles ► Mictrofilaments
Microtubles ► Hollow tubes made from protein ► Provide support & organelle transport ► Aide in cell division by forming centrioles (animal cells only) ► Support Cilia and Flagella ► Finger-like or whip-like structures that help with: ► Cell movement ► Movement along the cell surface
Microfilaments ► Long, thin fibers made of proteins ► Provide: ► Support and movement of cell ► Movement of the cytoplasm (called cytoplasmic streaming)
Maintaining a Constant Cell Environment Osmosis & Diffusion
Diffusion The process by which molecules of a substance move from areas of higher concentration of that substance to areas of lower concentration
Diffusion ► In the fluid and gaseous state of matter: Molecules are constantly in motion; colliding with one another and spreading out randomly This random motion has a general pattern Molecules move from an area where there are more molecules to where there are less molecules In other words, they move from an area of higher concentration to an area of lesser concentration.
Equilibrium ► The point at which the distribution of molecules and materials are evenly spaced out in any given area.
Osmosis ► The diffusion of water across a selectively permeable membrane. ► Some membranes are selectively permeable so some substances cannot pass through or across them (Those substances that “don’t mix well” with the fat in the membrane). ► Water is the exception: Water doesn’t mix with lipids however its molecules pass very rapidly through the membrane.
Osmotic Pressure ► The force exerted by osmosis. ► Tends to move water across a membrane from a dilute solution to a more concentrated solution. ► When solutions are of equal concentration (the desired state) then you have equilibrium and NO movement of water across the membrane.
Solution Types Relative to a cell, there are three solution types
Hypertonic ► When the solution outside of a cell is of higher concentration than the solution inside of a cell. ► Water will leave the cell in order to dilute the solution outside of the cell.
Hypotonic ► When the solution outside of a cell is of lesser concentration than the solution inside of a cell. ► Water will enter the cell in order to dilute the solution inside of the cell.
Isotonic ► When the solution outside of a cell is of the same concentration of the solution inside of a cell. ► Water will neither enter nor leave the cell. ► There will be no net movement of water.
Passive Transport ► Transport of water from areas of higher concentration to areas of lower concentration (either across a membrane or not) that requires NO energy.
Facilitated Diffusion ► Deals with the movement of molecules across a membrane that cannot cross a membrane by themselves. ► The channel proteins that facilitate the passage of these molecules are typically specific to that particular substance. In other words, the proteins have an affinity for whatever substance is dissolved in the solution and will attract it. ► Movement of the substance is reliant upon difference in charge of the molecules and the proteins. ► This process DOES NOT require energy and so is diffusion driven. ► Therefore, there must be a difference in concentration on either side of the cell membrane.
Active Transport ► Energy requiring process that moves molecules across a membrane and AGAINST a concentration gradient (from an area of lower concentration to an area of higher concentration).
Types of Active Transport ► Pumping action: “Pumps” move individual molecules across the membrane and against the concentration gradient. Chemical energy is required to power the pumping action of the protein channel. Calcium, potassium and sodium are among those substances transported across the membrane. ► Called a “Sodium Potassium Pump”
Types of Active Transport ► Endocytosis Particles “push” against the outside of the cell membrane causing a pocket to form. This pocket breaks loose on the inside of the cell forming an individual vacuole, or storage structure. Large molecules, clumps of food and other cells can be taken into the cytoplasm this way. ► Phagocytosis: A form or Endocytosis where large, solid particles are taken in. Amebas feed this way. ► Pinocytosis: When liquid forms pockets along the cell membrane, forms a vacuole and is taken into the cell cytoplasm. ► Exocytosis When large particles push against the cell membrane from the inside and the membrane surrounds it as it leaves the cell.