Question

1. Alcohol intake in excess of normal daily caloric requirements results in an increase in?

1. NADH/NAD⁺
2. Thiamin absorption
3. The ability of the liver to synthesize ATP
4. Weight
5. Gluconeogenesis

2. In aqueous solution, amphiphilic lipids such as lecithin:

1. Dissolve well due to the ability of the phosphate group to ionize.
2. Cannot interact with water because as lipids they are predominantly hydrophobic.
3. Can dissociate into a soluble hydrophobic portion and an insoluble hydrophilic portion.
4. Form sheets(micelles) composed of two layers.
5. Dissolve well due to the permanent positive charge on the choline nitrogen

3. Enzyme co-factors ALWAYS

1. Are inorganic molecules
2. Are covalently bound to enzymes
3. Form a complex with the substrate to make it more accessible to the enzyme
4. Maintain the native conformation of the enzyme
5. Provide a reactive group not found in the enzyme but necessary for its activity.

4. Proteolytic activation

1. Occurs at a modulator site that is distinct from the active site
2. Is initiated by an end product acting as a positive modulator
3. Occurs when a peptide segment is removed from a protein
4. Involves transcription of a regulatory protease
5. Produces a regulatory protein which activates the enzym

5. A nutrient known to be essential in ALL human diets is

1. Cholesterol
2. Choline
3. Palmitic acid
4. Sphingomyelin
5. Linoleic acid

Answer 1

1. A. NADH/NAD+

Alcohol dehydrogenase oxidize alcohol to aldehyde in liver, during this pathway hydrogen transfer to NAD+ and form NADH in turn NADH/NAD+ increases.

Thiamine absorption decrease due to lcohol consumption.

2. D. Form sheets (micelles) composed of two layers.

In aqueous solutions, amphiphilic lipids such as lecithin, form micelles, bilayer sheets, or liposomes. These properties of amphiphilic lipids are depend on hydration and temperature.

3. E. Provide a reactive group not found in the enzyme but necessary for its activity.

Cofactors are inorganic or organic molecules required by some enzymes their activity. Without cofactor enzyme is inactive and called as apoenzyme.

4. C. Occurs when a peptide segment is removed from a protein

Many enzymes are formed as inactive enzymes knon as zymogens or proenzyme, these zymogens are converted into active enzyme by proteolytic activation.

.5. E. Linoleic acid

Linoleic acid is essential fatty acid for human because it is polyunsaturated omega-6 fatty acid fatty acid. Prostaglandins and leukotrienes synthesized by linoleic acid.