Tag: biomolecules: chemical constituents of living cells

Questions Related to biomolecules: chemical constituents of living cells

Why tails of lipids in the membrane are towards inner part?

bio-chemistry lipids functions of lipids biomolecules: chemical constituents of living cells biochemistry

  1. The tails is non-polar hydrocarbon and so, protected with an aqueous environment

  2. The tail is polar hydrocarbon and so, is protected from aqueous environment

  3. The non-polar or hydrophobic hydrocarbon trails of lipid, being on inner side ensure their protection from aqueous environment.

  4. The tail is hydrophilic so, it tends to be located in the aqueous inner side of membrane

Show answer
Correct Option: C
Explanation:

The tails of the lipids are made up of fatty acids. These are non-polar hydrophobic so they tend to arrange away from the cytoplasmic face as well as the extracellular face. So, they avoid aqueous medium by arranging themselves towards the inner part of the cell membrane.

Hence, the correct answer is 'The non-polar or hydrophobic hydrocarbons tails of lipid, being on inner side ensure their protection from the aqueous environment.

Which of the following can be traced in phospholipids of brain tissue and soybeans?

bio-chemistry lipids functions of lipids biomolecules: chemical constituents of living cells biochemistry

  1. Phosphoglycerides

  2. Phosphoinositides

  3. Cholesterol

  4. None of the above

Show answer
Correct Option: B
Explanation:

Phosphoinositides make up a small fraction of cellular phospholipids, They play a fundamental role in controlling membrane-cytosol interfaces, regulation of membrane traffic and the permeability and transport functions of membranes. They are found in brain tissue in animals and soybean seeds. Thus the correct answer is option B.

Deficiency of EFA causes

bio-chemistry lipids functions of lipids biomolecules: chemical constituents of living cells biochemistry

  1. Follicular keratosis

  2. Kidney failure

  3. Sterility

  4. All the above

Show answer
Correct Option: D
Explanation:

Essential fatty acids (EFA) are those fatty acids that body cannot produce on its own and therefore must be supplied from the diet. Deficiency of EFA causes many disease conditions like dry and scaly skin, follicular keratosis (hard and dry skin around hair follicles), bumps on back of upper arms, color variation of skin, dry eyes, mouth and throat, menstrual cramps, dry vagina, excessive thirst, eczema, asthma, hay fever, painful joint. In severe cases, it may result in kidney failure and sterility.

Thus, the correct answer is option D. 

Sterols are not fats but solid alcohols. These are put as lipids because they form

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Fats and fatty acids

  2. Triglycerides

  3. Cholesterol

  4. Ester and fatty acids

Show answer
Correct Option: C

Cholesterol is a precursor for each  of the following except

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. bile salts

  2. Vitamins D

  3. insulin

  4. steroids

Show answer
Correct Option: A

At physiological temperature, sterols in biological membranes

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Increase their fluidity

  2. Decrease their fluidity

  3. Increase their permeability to water

  4. Decrease their permeability to water

Show answer
Correct Option: A
Explanation:

Biological membranes are made up of lipid bilayer. These sterols affects the fluidity and rigidity of the membrane. At physiological temperature, sterols in biological membranes increase their fluidity but makes them more stronger and rigid. Environmental conditions like higher temperatures or unsaturated fatty disrupts close packing of lipids. This results in increase in the fluidity of the membrane. The membranes become more permeable to water. However, at lower temperatures, membranes become rigid. 

So the correct option is 'Increase their fluidity'.

Which of the following is a precursor of vitamins and steroid hormones

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Lipids

  2. Cholesterol

  3. Lipoic acid

  4. None of the above

Show answer
Correct Option: B
Explanation:

Cholesterol acts as precursor of Vitamin D and steroid hormones like estrogen, testesterone

So, the correct answer is 'Cholesterol'

Beta-oxidation mainly takes place in _________.

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Cytoplasm

  2. Mitochondria

  3. Golgi bodies

  4. None of the above

Show answer
Correct Option: B
Explanation:

In biochemistry and metabolism, beta-oxidation is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA, which enters the citric acid cycle, and NADH and FADH2, which are co-enzymes used in the electron transport.

Which among the following is the anabolic process?

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Glucose converts to lactic acid.

  2. Acetic acid is converted to cholesterol

  3. Glucose converted to pyruvic acid

  4. Glycogen converted to glucose

Show answer
Correct Option: B
Explanation:
Anabolic process involves the synthesis of complex molecules from simple molecules. Cholesterol is a large and complicated molecule. The starting point of cholesterol synthesis is acetic acid.
So, the correct option is 'Acetic acid is converted to cholesterol'

Steroid is derived from

bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

  1. Cholesterol

  2. Thyroxine

  3. Vitamin A

  4. Fatty acid ester

Show answer
Correct Option: A
Explanation:
Steroids are the organic molecule which plays an important role in the growth and development of the body. The molecular structure consists of 17 carbons which are arranged in four fused structure. It is found in plants, animals and fungi. Cholesterol which is the derivative of steroid forms an integral component of the cell membrane and alter the membrane fluidity. The also acts as hormone precursor for steroidal hormones.
So, the correct answer is option A.