Lab Terminology Flashcards
Dissecting microscope
For viewing objects that can be seen with the unaided eye in more detail. Shows 3-dimensional view of objects but not as powerful as compound light microscope.
Compound light microscope
For viewing cells and some cell organelles. Tissue layers may be visible but depth of focus decreases with increasing magnification.
Electron microscope
For viewing viruses and macromolecules. Uses beam of electrons instead of light.
Resolving power
The ability of a lens to clearly separate fine detail, to distinguish two close points as separate; related to the wavelength of light and the numerical aperture of the objective.
Magnification
The enlargement of an object’s image through a lens.
Contrast
Differential absorption of light by parts of a specimen.
Scanning objective lens
(magnifies images by 4 times)
5000 micrometers
Low-power objective lens
(magnifies images by 10 times)
2000 micrometers
High-power objective lens
(magnifies images by 40 times)
500 micrometers
Oil immersion lens
(magnifies images by 100 times)
200 micrometers
Chromophore
Colored part of the stain
Stains
Dyes composed of salts that contain a positive ion and a negative ion.
Acidic dye
Chromophore (stain color) is the negative ion
Basic dye
Chromophore (stain color) is the positive ion
Positive stain
A stain that colors the cells but not the background
Useful for viewing major cell parts of eukaryotic cells such as the plasma membrane and nucleus
Negative stain
A stain that colors the background but not the cells.
Useful for determining the shape and arrangement of bacteria cells and to view the outline of colorless cells against a colored background
Iodine
Iodine potassium iodide
The iodine-KI forms a complex with starch molecules in cells causing the iodine to change color from yellow to dark blue.
Oscillatoria
Oscillatoria belongs to a group of prokaryotes called cyanobacteria (“blue-green algae”)
Trichomes
Stacks of individual cyanobacteria (oscillatoria) that are disc-shaped.
Amoeba
A unicellular eukaryote and a protists. They move by extending their cytoplasm to form pseudopodia
Formation of Pseudopodia
Involve a change in cytoplasm consistency from sol to gel.
Mechanical stage control knobs
Moves the specimen into the center of the field of view.
Field of view (FOV)
Circle of light that you see when looking through the ocular lenses.
Revolving nosepiece
Changes objective lens
Parfocal
When one lens is focused, all of the objective lenses are focused (with fine adjustments).
Fine focus knob
Bring the specimen into focus with the low-power objective lens
Working distance
Distance between objective lens and slide.
Scanning objective lens gives the greatest working distance.
Coarse focus knob
Brings the stage/slide as close as possible to the scanning objective lens.
Interpupillary distance
Distance between the pupils of YOUR eyes
Hypothesis
Hypotheses are general (universal) statements that cannot be tested directly based on facts or experience.
Prediction
Specific statement that can be made based on a universal hypothesis
Principle of falsifiability
It is impossible to prove a hypothesis to be true.
Independent variable
Variable being manipulated or changed by the scientists who are conducting the experiment.
Dependent variable
Variable being measured in response to the independent variable (it DEPENDS on the independent variable).
Controlled variables
Variables that are held constant throughout the experiment, so they don’t interfere with the independent variable.
Controlled variables are not the same thing as a control group.
Polypeptide
A polymer that contains many amino acids linked together
Peptides
Shorter polypeptides (fewer than 50 amino acids
Polypeptide chain
A primary structure that contains several hundred amino acids
Albumin
Protein found in blood plasma, where it helps maintain osmotic concentration of blood; and insulin is a regulatory protein (hormone) that controls blood glucose levels.
Enzymes
Organic catalysts that speed up metabolic reactions
Pepsin
Digestive enzyme active in the acidic conditions of the stomach where it helps break down proteins contained in food.
Positive test
Color change is observed indicated particular molecule is present.
Negative test
Color change is not observed indicating particular molecule not present.
Hydrolysis
Water reacts to break those chemical bonds and separate large organic molecules (polymers) into smaller molecules (monomers
Dehydration Synthesis
When smaller molecules (monomers) form chemical bonds as water is produced.
Biuret reagent
Acts as an indicator by changing color in the presence of proteins or peptides when the amino group in a polymer chemically combines with the copper ions in biuret reagent:
Changes color from blue to violet in the presence of proteins
Changes color from blue to light violet/pink in the presence of peptides
Monosaccharide
Only one sugar unit
ex: Glucose
Disaccharide
Composed to two sugar molecules.
ex: Maltose (two glucose)
Reducing sugars
Sugars with free carbonyl groups, in either a closed ring, open ring or linear form.
Can donate electrons to other molecules
Benedict’s reagent
Indicate the presence of reducing sugars:
Brick red indicates a very high concentration of reducing sugars
Orange indicates a high concentration of reducing sugars
Yellow indicates a moderate concentration of reducing sugars
Green indicates a low concentration of reducing sugars
Lugol’s reagent
In the presence of starch, Lugol’s iodine turns from its normal color of dark yellow to a bluish-black color.
Triglyceride
Composed of three fatty acids and a glyceride molecule.
Prokaryotic Cells
- No nuclei or membranous organelles
- Enclosed by a plasma membrane (regulates passage of molecules in and out of cytoplasm)
Eukaryotic Cells
- Nucleus, bound by nuclear envelope
- Contains nucleoplasm
- Contains cytoplasm in cell
- Cytoplasm fluid called cytosol
Diffusion
Molecules will flow from an area where they are at a high concentration to an area where they are at a lower concentration if “permitted” (most often by size and polarity) to pass through the membrane.
Osmosis
Diffusion of water molecules across a semi-permeable membrane
Cytoplasmic streaming
Flow of cytoplasm within a cell. The flow occurs along actin filaments and carries nutrients and smaller organelles in the direction of flow.
Passive
Does not require energy
ex: Diffusion
Tonicity
Compare two solutions of unequal solute concentration
Isotonic
Solution is equal / the same as the solute (particle) concentration as the cell
Hypertonic
Solution has a higher solute concentration than inside the cell
Hypotonic
Solution has a lower solution concentration than inside the cell.
Turgid
Swollen and hard due to turgor pressure.
Flaccid
Lacking turgidity, floppy and loose.
Cells pulled away from cell wall.
Hemolyzed
Cell swells and rupture of cell membrane (cell death)
Crenated
Cells shrink and their forms become altered into a disc shape, or scalloped edge in a hypertonic solution.
Animal cells are exposed to a hypertonic solution, where solution in which the cells are bathed has a high concentration of solutes
Plasmolyzed
Cells lose water in hypotonic solution.
Water flows out of the cells and into the surrounding fluid due to osmosis causing a process of contraction or shrinkage of the protoplasm of a plant cell and is caused due to the loss of water in the cell.
Turgor pressure
Force within the cell that pushes the plasma membrane against the cell wall
Iris diaphragm
Allows you to adjust the amount of light passing through the condenser
Light condenser
A glass lens or lens system located within or below the stage (sub-stage) on compound microscopes that focuses the light on the specimen, adjusts the amount of light on the specimen, and shapes the cone of light entering the objective.
