Chapter 13: Enzyme Histochemistry Flashcards
What are enzymes?
Enzymes are proteins that catalyze reactions occurring in biological systems.
How does biological oxidation occur?
Biological oxidation occurs with the addition of oxygen, the loss of hydrogen or the loss of electrons.
A compound is reduced when what is removed?
A compound is reduced when there is a loss of oxygen, a gain of hydrogen or a gain of electrons.
The compound or chemical group in which a specific enzyme works is known as the:
Substrate.
Tissue for some enzyme demonstration should be fixed if possible because:
Considerable diffusion artefact may be seen on unfixed frozen sections for some enzymes, particularly those that are water soluble.
Tissue for enzyme studies has been fixed in cold calcium formalin. What would the best storage medium be?
After fixation, tissue may be stored in gum sucrose solutions at 4C for several weeks.
Enzymes that act on substrates be adding water belong to the group known as:
Hydrolases.
The optimum procedure for freezing muscle biopsies is:
Isopentane at -150C.
The supply of isopentane has been depleted, although liquid nitrogen is available, and a muscle biopsy needs to be frozen. In this case, what would be the best freezing procedure?
The muscle needs to be dusted with talc, then frozen with liquid nitrogen.
The most frequently used methods of demonstrating hydrolytic enzymes involve:
Simultaneous coupling.
When used on muscle biopsies, the alpha-napthyl acetate esterase stain demonstrates:
Motor end plates on muscle.
Paraffin sections may be used for what stain?
The napthol AS-D chloroacetate esterase stain is a specific esterase stain that can be used on paraffin sections.
The napthol AS-D chloroacetate esterase stain demonstrates:
Granulocytes.
The ATPase reaction involves:
Simultaneous coupling and metallic substitution.
The final colored product in the ATPase reaction is:
Cobalt sulfide.
With the ATPase stain, pH 9.4, on a normal muscle biopsy, the results would show:
Dark type IIA and IIB fibers and light type I fibers.
What does the acid phosphatase reaction demonstrate?
The alcohol residue of napthol AS-BI phosphate.
What does the acid phosphatase reaction on muscle demonstrate?
Lysosomes.
The end product of the alph-napthol acetate esterase, acid phosphatase and alkaline phosphatase is:
An azo dye.
The NADH diaphorase or reductase technique on muscle demonstrates:
Mitochondria, Z-band material and sarcoplasmic reticulum.
Microscopic evaluation of NADH diaphorase stains show marked precipitate on the section. This is most likely the result of:
The incubating solution was buffered to pH8.5, anything above 8.0 will cause this precipitate.
Succinic dehydrogenase procedures demonstrate:
Mitochondria only.
The absence of phosphorylase activity in muscle indicates:
McArdle disease.
The phosphorylase stained sections were not read for several days. What should we do?
They should be restained in dilute iodine.