June 8, 2010.
Compound Light Microscope
-Most familar type of microscope, -uses light to iluminate the object & lenses & mirrors to bend light to form an image, -can be used to look at living and nonliving things, -maginification limited to 2000x, and resolution 200 nanometers.
Preparing Specimens for View
-Specimens of dead or nonliving tissue can be perminently mounted, -living tissue can be nounted on a simple wet slide, -slide can be stained to show details (kill specimens), & -chemicals can be used to slow down fast-moving specimen.
-Allows much higher magnification while still having a very high resolution, -2 main types:Tramsmission and Scanning
Trasnsmission Electron Microscope
-The TEM provides very high magnification with excellent resolution (maximum magnification is 1,500,000x whit a resolution of 0.13 resolution), -it can only look at very thin slices or sections of and object and has very little depth of field, -preparation of a specamen is a very complex and the specamen obviously cannot be living, -could cost up to $500,000.
How the Transmission Electron Microscope Works
-The TEM is similar to the light microscope except for: -a beam of electrons replace a beam of light, -the glass lenses are replaced by nagnets to bernd the e-beam, and the image is projected onto a TV screen or pohotgraphic plate insead of being viewed with the eye.
Scanning Electron Microscope
-The SEM yields less magnification than a TEM but gives a high-resolution and projects a 3-D image, -3000x magnification, & -2.0 nanometers resolution.
How the Scanning Electron Microscope Works
-It sweeps the object that is being examined iwth a beam of electrons, -electrons are knocked off the specimen or bounce back from the e-beam, -detectors collect these e-and use them to render an image, & -SEM samples are typically coated with a thin layer of gold in a vacuum so they are definitely not alive.
Jansen Brothers build the 1st microscope by placing 2 lenses in a tube
Robert Hooke studies multicelluar structures such as cork under the microscope, he is the first to bescribe celluar structure and is the first to use the word "cell" to describe them
Anton Von Leuuwenhoek is the first to observe microorganisms including protists and bacteria, will not be seen again for over 100 years.
"The Golden Age" (the 1800's)
-Germ theory of disease, -Louis Pasteur's practical discovery in wine-making and pasturization, - the cell theory.
History of the Cell Theory
Matthais Schleiden (a botonist) and Theodor Schwann (a zoologolist) independently develop the cell theory which createds the modern science of biology Rudolph Virchow later contributes to the idea.
The Cell Theory
1.) Cells are the structural unit of life. 2.) Cells are the functional unit of life. 3.) All cells come from preexisting cells.
2 Groups of Cells
Prokaryotic cells and Eukaryotic Cells
-Smaller by a power of 10, -lack membrane-bound organelles, -appeared 1st in the fossil reccord, -more primative, & -less complex.
-Larger, -have membrane-bound organelles, -appeared later in the fossil reccord, and -more complex.
Forms the boundary cell and determines what materials may enter and leave the cell. Cell membranes are Selectively permeable, which means that some materials can pass through them while other materials cannot.
-usually the largest organelle in the cell, -is surrounded by a double layer of plasma membrane called the nuclear envelope, which has pores that allow materials to pass in and out, -contains the cell's genetic informationin the form of DNA, -the DNA molecules combine with proteins to form chromatin , that can form structures called chromosomes, & contains a dark staining body called the nucleolus, which makes the rhibosomes.
a double-layer of fo plasma membrane that surrounds the nucleus, it has pores that allow materials to pass in and out.
The DNA molecules conbine with proteins to form chromatin, that can form structures called chromosomes.
A dark staining body in the nucleus which make the ribosomes
is a network of membranous tubes and canals that make up over 1/2 of the plama membrane in the cell, and divided into the rough and smooth ER and is involved in transporting materials through the cell.
is studded with small non-membrane bound organelles called ribsomes and is the site of protein synthesis
Lacks the riboscomes and lacks the ribosomes and is mainly involved in lipid synthesis
its primary function is to put the finishing touches on protein synthesis, package cellular products, and, if necessary prepare them fomr release from the cell, is made up of a series of flattened membrane sacs that resemble a stack of pancakes.
is the organelle in which energy for the cell is released, and glucose molecules are broken down in the presence of oxygen and form carbon dioxide and water, and the energy released is used to make ATP, is an oval structure that is covered by a layer of plasma mambrane , inside more membrane is found in folded up layers called cristae, celluar respiration occurs on these membranes.
is an organelle found only in plants and in some protists , is the site of photosynthesis, the green color of plants comes form the cholorophyll moleules found in th cholorplast, has folded membrane inside of membrane
are small vesicles or pouches of membrane that contain digestive enzymes, fom form the golgi apparatus, and their functions include breaking down damaged cell parts and reabsorbing tissue, are extemely common in the cells at the base fo a tadpole's tail.
si a network of fibers that help the cell maintain it's shape are involved in movement of the celland are used during mitosis and meiosis, made up of 3 components : microtubules, microfilaments, and intermediate filaments
are the largest of the three elements and are hollow tubes made of the protin tubulin
are the smallest and are capable of contracting and lengthening
are the most common and are primarily for structural support
cell membranes are selectively permeable, allow some materials to pass through but not others
Factors for Permeability
-Size: small over large -Charge: Neutral ions over charged ions, Polarity: nonpolar over polar, solubility in lipids: soluble over insoluble
Membrane Transport Processes
Active Transport and Passive Transport
Requires the expendature of energy.
Does not require the expendature of energy.
the most common form of passive transport, is the movement of a substance from an area of higher concentration to an area of lower concentration
Factors Necessary for Diffusion
the membrane i spermeable to the substance in question and there is a concentration fradient (a difference in concentration between two areas).
is the movement of water from an area of higher concentration to an area of lower concentration , is the diffusion of water.
is a solution where the solute concentration is higher and the water concentration is lower than a cell that is placed into it
is one where the solution has a higer wate concentration (and a lower solute concentration) than the cell placed in it
is one that has the same water and sloute concentrations as the cell placed in it
is a passive process similar to regular diffusion, the only difference is that it involves the presence of carrier proteins and increases the rate of diffusion
Processes that allow materials to pass through the membrane that cannot pass through diffusion because of : too large , ions charged, or against a concentration gradient
is a way for cells to bring in moleucles that are too large to pass through the membrane, the cell membrane engulfs the object and forms a vesicle it takes energy to change the shape of the cell membrane
Receptor Mediated Endocytosis
is a form of endocytosis that uses protein receptors to "grab" certain molecules this is important in the uptake of cholesterol from the blood
works like endocytosis in reverse, vesicles in the cell release waste products and cellular products out of the cell
are special proteins in the membrane that transport ions across the memebrane using energy from a molecule called ATP