Bio 108 Lab Exam 1
Electron microscopes use ______ to resolve images, whereas light microscopes use ________ to resolve images.
diffraction of electron beams; light and lenses
Lactose which is composed of one glucose unit and one galactose unit can be classified as
disaccharide
If molecule 1 is more soluble in lipid than in water when compared to molecule 2, then molecule 1 will have a ________ lipid/water partition coefficient.
higher
When a severely dehydrated patient is brought to the hospital, an IV of normal saline (isotonic to blood cells) is started immediately. Distilled water (with few solutes) is not used because
it would cause the patient's blood cells to swell and eventually burst
How is K determined?
k = solute concentration in lipid / solute concentration in water
Osmosis moves water from a region of _______ to a region of _______.
low concentration of dissolved material: high concentration of dissolved material
If molecule 1 is less soluble in lipid than in water when compared to molecule 2, then molecule 1 will have a ________ lipid/water partition coefficient.
lower
Large molecules that contain carbon and are held together by covalent bonds are best described as
macromolecules
Molecule 1 has a higher lipid/water partition coefficient than molecule 2. Assuming all else is equal, which statement is correct?
molecule 1 will move across the membrane faster
Molecule A has a larger molar volume than molecule B. Assuming all else is equal, which statement is correct?
molecule B will move across the membrane faster
Monomers that make up carbohydrates like starch are called
monosaccharides
A protein can be best described as a polymer
of amino acids
What helps cells maintain tugor pressure in plants?
osmosis
When placed in water, wilted plants lose their limpness because of
osmosis of water into the plant cells
The difference between osmosis and diffusion is that
osmosis refers specifically to the movement of water, whereas diffusion is the movement of molecules.
Enzymes are highly sensitive to pH and temperature becasue
pH and temperature affect their three-dimensional structure and side-chain chemistry
Proteins consist of amino acids linked together by
peptide bonds
The tertiary structure of a protein is determined by its
primary structure
Members of the domains Bacteria and Archae are
prokaryotes
A macromolecule with many hydrogen and peptide bonds is most likely a
protein
The statement "enzymes are highly specific" means that specific
reactions involving specific substrates are catalyzed by specific enzymes
An alpha helix is an example of the _________ level of protein structure
secondary
When placed in a hypertonic solution, animal cells
shrink
A compound microscope _________ light, and a dissecting microscope __________ light.
transmits; reflects
When placed in hypertonic solution, plant cells
undergo plasmolysis
How does one measure objects using a compound light microscope?
using the vernier scale
Are the primary structures of a protein unique to that protein?
yes
Which is responsible for making every amino acid unique?
"R" group
18.0 nm is eqaul to ____ mm
0.000018
500 micrometers is equal to how many cm, mm, nm, and m?
0.05 cm, 0.5 mm, 500,000 nm, and 0.0005 m
What is the typical magnification of the ocular lens?
10x
5.0 mm is eqaul to ____ nm
5,000,000
Triglycerides are synthesized from
A glycerol molecule attached to three fatty acids
Substage condensor
A lens that focuses the light on the object lying on the stage of a compound microscope
Identifying Elodea under microscope
A multicellular aquatic plant with stif cell wells. Has a single nucleus and multiple choroplasts
What is descriptive statistics?
A numerical summary of the data set
How do you calculate enzyme activity from absorbance?
Activity = absorbance / (1.36 x 10^-4 nM^-1 x T) where T = time of incubation (usually 10 minutes)
After the compound microscope is all cleaned up, what is the next step?
Adjust the substage condenser to the highest postition (at the stage level). You turn the light on to the lowest intensit an open the iris diaphragm full to give maximum illumination. You can then proceed to using the microscope
The backbone of a nucleic acid molecule is made of
Alternating sugars and phosphate groups
In general, what affects enzyme activity?
Anything that changes the shape of the enzyme's binding spot. This includes pH, ion concentration, or temperature
What is the relationship between magnification and depth of field in a dissecting microscope?
As the magnification increases, the depth of field decreases (higher aperture, back objects are more blurry)
When is it useful to use a dissecting microscope?
Because of its large depth of field and uninverted image, it is useful for microdissection and manipulation of small objects.
Is the stage illuminated on a compound microscope from below or above?
Below
What is the order of the pathway of light through a compound micrscope?
Condenser -> Iris diaphram -> stage -> objective lens -> ocular lens
Coarse and fine adjustment knobs
Controls the focusing of the image. The larger knob is for coarse adjustment. The fine focus knob is on the outside of the coarse focus knob.
How do you measure distances in jMol?
Double click on the first point and then double click on the second point
What is the general equation for an enzyme-catalyzed reaction
E + S ---> ES ---> E + P
Where is the magnifying powers of a dissecting microscope found?
Engraved on the knob
How do you zero a spectrophotometer and when should you do it?
First, make sure the machine is on the correct wavelength. Then, adjust the transmittance to 0 with the sample holder empty. Then, clean blank cuvette with Kimwipe and insert into sample holder. Adjust the absorbance to zero. You must do this before every sample
How to reduce or enlarge image in jMol
Hold down the shift button and left mouse button and move mouse backward and foward
What type of bond connects two complementary nucleotides together?
Hydrogen
How does substrate concentration affect a catalyzed reaction?
Product will increase into equilibrium is met, due to availability of enzyme binding spots.
How do you adjust magnification on a dissecting microscope?
Rotating the knob on the side
A beta pleated sheet organization in a polypeptide chain is an example of _______ structure
Secondary
What does the hemolysis rate represent?
Shows how easily solutes can move through a membrane
Body tube
The 160mm tube that you look through that is home to the ocular lens
The characteristic of phospholipids that allows them to form a bilayer is
The hydrophboic fatty acid tail and the fact that they are amphipathic.
Which magnification should you start off with? (compound microscope)
The lowest magnification, usually 4x
You look at the label on a container of shortening and see the words "hydrogenated vegetable oil." This means that during processing, the number of carbon-carbon double bonds in the oil was decreased. What is the result of decreasing the number of double bonds?
The oil is now solid at room temperature
Stage
The platform that the specimen is put onto
If a shallow pan is filled with water, a drop of red ink is placed in one end of the pan, and a drop of green ink is placed in the other end, which of the following will be true at equilibrium?
The red and green inks will be uniformly distributed throughout the pan
Rotatable nose-piece
The rotating piece that bears three objective lenses on a compound microscope
What should be done before going to higher magnifications?
The specimen should be brought into focus on lowest magnification on;y using the adjustment knobs
Where are the transmittance, absorbance, and wavelength knobs located?
The transmittance is on the left, the absorbance on the right, and the wavelength on the top.
What types of light are offered by the dissecting microscope and what situations warrant which light?
There is incident light (above) which is better for color and depth perception (3D-viewing) There is also transmitted light (below) which is useful for light permeable objects
Identifying red blood cells under microscope
They are anucleate when mature, meaning they lack a nucleus. They are filled with hemoglobin which can temporarily bind O2.
How do enzymes work?
They catalyze chemical reactions without being permanently changed or used up. They lower the activation energy by having one or more active sites that help stabilize the intermediate steps in a chemical reaction and make it more likely to occur
Identifying amoeba under microscope
Unicellular protist that has a cell membrane, cytoplasm, and organelles. Move by cytoplasmic streaming in which they extend a pseudopod and move cytoplasm into new area. It has a blob appearance and feeds through phagocytosis, in which they surround and engulf food. Have one nuclei and contractile vacuole.
Identifying paramecium under microscope
Unicellular protists that move using cilia. They have an oral groove in which they draw food into the mouth and then into a food vacuole. a contractile vacuole maintains proper water balance within the cell. The nucleus is clearly visible. I saw the cell membrane, nucleus, and cilia
How does a dissecting microscope work?
Uses prisms to eliminate image inversion. It has variable or zoom magnification by varying the distance between the objective and ocular lens (usually 10x magnification).
What is the first thing you do when using a compound microscope?
You clean the ocular, objectives, and substage condenser with a special lens paper.
Where should your gaze be when rotating the nose piece?
You should be looking at it from the side
In biological membranes, the phospholipids are arranged in a _______, with the _______.
bilayer; fatty acids pointing towards each other
Active transport
Molecules are moved across the membrane against the concentration gradient. Requires energy through ATP hydrolysis.
Facilitated diffusion
Molecules are moved through transport molecules across the membrane along the concentration gradient. Energy is not required.
Simple diffusion
Molecules diffuse through the membrane along the concentration gradient which does not require energy
Iris diaphram
Mounted immediately below the substage condenser and can be regulated by an arm. on a compound microscope
Lamp housing
Mounted on the base below stage opening. An off/on switch and light intensity control knob are located on the microscope's base for a compound microscope
How can a reaction be sped up?
Increase enzyme concentration
Lipids are
Insoluble in water, important for energy storage, hydrophobic, and important constituents of biological membranes
What does the enzyme bGAL do?
It catalyzes the reaction that breaks lactose down into glucose and galactose
What is ONPG?
It is modified substrate that resembles lactose but has a colorless, unstable dye molecule attached to the galactose. If bGAL is present, it hydrolzes the chemical bond and releases the dye from galactose. Forms a bright yellow product that can be used to measure concentration.
Objective lens
Lens closest to specimen that provides the magnification
Ocular lens
Lens that magnifies the image produced by the objective lens
What affects the rate of diffusion of a substance across a membrane?
Lipid solubility (K partition coefficient), concentration gradient and molar volume
Where do water molecules concentrate in DNA?
Mainly in the major groove
A nucleotide in DNA is made up of
a base plus a deoxyribose sugar plus phosphate
A nucleotide contains a pentose sugar, a phosphate group, and
a nitrogen containing base such as adenine and thymine
A concentration gradient of glucose across a membrane means that
there are more molecules of glucose on one side of the membrane than the other
A molecule with the formula C16H30O15 is a
carbohydrate
The atoms that make up all carbohydrates are
carbon, hydrogen, and oxygen
Two important polysaccharides made up made up of glucose monomers are
cellulose and starch
Quaternary structure is found in proteins
composed of subunits
All proteins
consist of one or more polypeptide chains
The molecules that are acted on by an enzyme are called
substrates
If a red blood cell is placed in a hypotonic solution it will
swell and burst
If a plant cell is placed in a hypotonic solution, it will
swell but retain its shape
If a plant cell is placed in an isotonic solution, it will
take up and release water at an equal rate
If a red blood cell is placed in an isotonic solution, it will
take up and release water at an equal rate
Lyses refers to
the cell becoming transparent