Bile salt ________________surface tension
Answer: B
Correct answer: Decreases
Bile salts are amphipathic: a hydrophilic face and a hydrophobic one. They therefore gather at the fat-water interface and lower the surface tension, breaking large fat globules into a fine emulsion. That multiplies the surface area available to lipase, which can only work at the interface.
Please log in or register to report this question.
The inactive organic molecular portion of enzyme is
Answer: B
Correct answer: coenzyme
A coenzyme is the small organic molecule an enzyme needs to work - NAD, FAD, coenzyme A, and the rest, many of them derived from vitamins. It is inactive on its own, and it joins the apoenzyme to make the holoenzyme. A metal ion serving the same purpose is a cofactor rather than a coenzyme.
Please log in or register to report this question.
What are isoenzymes?
Answer: C
Correct answer: Multiple forms of enzyme
Isoenzymes are different molecular forms of an enzyme that catalyse the same reaction but differ in structure and in kinetic properties. They arise from different genes or different subunit combinations, and having several lets the same reaction be tuned differently in different tissues - which is what makes the LDH pattern useful in diagnosis.
Please log in or register to report this question.
Intracellular enzymes
Answer: B
Correct answer: synthesize cellular material and perform catabolic reaction
Intracellular (endo-) enzymes work inside the cell and do both halves of metabolism: the anabolic reactions that build cellular material and the catabolic ones that break substrates down for energy. Extracellular enzymes, by contrast, are secreted and are almost entirely degradative.
Please log in or register to report this question.
Enzymes that are involved in the feedback inhibition are known as
Answer: C
Correct answer: Allosteric enzymes
Feedback inhibition works because the end product binds at a regulatory site rather than at the active site - and an enzyme with such a site is by definition allosteric. An apoenzyme is a protein without its cofactor, a holoenzyme the complete assembly, and a coenzyme the organic cofactor itself.
Please log in or register to report this question.
Removal of phosphoryl groups is catalyzed by ___________
Answer: C
The enzymes that catalyze the ADP-ribosylation and inactivation of key cellular enzymes or proteins are diphteria toxin and cholera toxin. Dinitrogenase reductase is responsible for the regulation of biological nitrogen fixation. The attachment of phosphoryl groups to specific amino acid residues is catalyzed by protein kinases.
Please log in or register to report this question.
Allosteric enzymes consist of several
Answer: A
Correct answer: polypeptide chains
An allosteric enzyme is built of several polypeptide subunits. That is what makes allosteric behaviour possible: a change of shape induced in one subunit is transmitted to its neighbours, so the whole molecule shifts between a more and a less active state.
Please log in or register to report this question.
Many enzymes consist of a protein combined with low molecular weight organic molecule called as
Answer: B
Correct answer: co-enzyme
A coenzyme is a small organic molecule that an enzyme needs in order to work - NAD, FAD, coenzyme A, most of them derived from vitamins. Protein plus coenzyme makes the active holoenzyme; the protein alone is the apoenzyme. A metal ion serving the same purpose is called a cofactor rather than a coenzyme.
Please log in or register to report this question.
Average volume of an RBC is _________µm³
Answer: B
Correct answer: 86
The mean corpuscular volume is about 86-90 fL (μm3). It is one of the standard red cell indices: below the range the cells are microcytic, as in iron deficiency and thalassaemia; above it macrocytic, as in vitamin B12 or folate deficiency.
Please log in or register to report this question.
An apoenzyme dissociates from its coenzyme because of a
Answer: A
Correct answer: Change in pH
A coenzyme is held to its apoenzyme by weak non-covalent forces, many of them involving charged groups. A shift in pH alters the ionisation of those groups, so the attraction is lost and the two dissociate - leaving the apoenzyme inactive.
Please log in or register to report this question.
