Tag: cell membrane

Quizzes (6) Questions (56)

Questions Related to cell membrane

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

 .......... is the regulatory enzyme in the fatty acid biosynthesis.

  1. Aminoacyl synthetase

  2. Acetyl CoA carboxylase

  3. Peptidyl transferase

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Fatty acids are components of the phospholipids that make up the bulk of the lipid bilayers of all cellular membranes. It is synthesized by cytosolic acetyl-CoA  through carboxylation by acetyl-CoA carboxylase into malonyl CoA. This conversion occurs primarily in the liver, adipose tissue and lactating mammary glands, where the fatty acids are combined with glycerol to form triglycerides
So, the correct answer is option B.
Multiple choice bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

The oil of which one of the following plants is edible and rich in poly unsaturated fatty acids?

  1. Aleurites fordii

  2. Cocos nucifera

  3. Carthamus tinctorius

  4. Ricinus communis
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Carthamus tinctorius, commonly known as safflower, produces an edible oil that is exceptionally rich in polyunsaturated fatty acids, particularly linoleic acid. The other plants listed either yield oils with different fatty acid compositions or are not primarily known for edible polyunsaturated oil.

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

Cholesterol belongs to which of the following groups

  1. Steroids

  2. Neutral fats

  3. Waxes

  4. Phospholipids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The steroids are composed of seventeen carbon atoms, bonded in four fused rings: three six-membered cyclohexane rings and one five-membered cyclopentane ring. The steroids differ in the functional group attached to this four-ring core and by the oxidation state of the ring.

Steroids such as cholestrol decrease membrane fluidity. Like lipids, these are highly concentrated energy stores. They are normally metabolized and excreted.
So, the correct option is 'Steroids'.

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

Which one of the following is not correctly matched?

  1. Cutin- Consists of long chain fatty acids and polyhydroxy derivatives of these fatty acids

  2. Pectin-Methylated polymer of flacturonic acid

  3. Lignin- Formed by condensation on coniferyl alcohol

  4. Callose- Glycosylated aliphatic acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Callose is a polysaccharide composed of glucose residues linked together through beta-1,3-glucosidic bonds, not a glycosylated aliphatic acid. All other listed cell wall components and their chemical natures are correctly matched.

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

Which one of the following is not a correct statement regarding the design of biological membranes?

  1. Carbohydrate molecules associated with membranes tend to be associated with protein molecules embedded in the membrane

  2. Hydrophobic ends of phospholipid molecules in the outer monolayer of the membrane are exposed directly to the extracellular environment

  3. Cholesterol is a type of lipid frequently found in membranes of animal cells

  4. Protein molecules can be located on the inner and outer surfaces of the membrane as well as traverse the entire thickness of the bilayer
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
In a cell membrane, the hydrophobic ends of phospholipid molecules in the outer monolayer of the membrane are sandwiched between the hydrophilic heads of the phospholipid bilayer and are not exposed to the extracellular environment.

So, the correct answer is 'Hydrophobic ends of phospholipid molecules in the outer monolayer of the membrane are exposed directly to the extracellular environment'.
Multiple choice bio-chemistry lipids derived lipids biomolecules: chemical constituents of living cells cell membrane

In the fluid mosaic membrane model, the phospholipid bilayer

  1. Is sandwiched between two protein layers

  2. Is covered by a single protein layer

  3. Has proteins embedded in it

  4. Lies on top of a single protein layer
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the fluid mosaic model, the phospholipid bilayer has integrated as well as peripheral proteins embedded in it. The integrated proteins are found on the inside and span across the bilayer, while the peripheral proteins are found at the periphery of the lipid layers.

So the correct answer is 'has proteins embedded in it'.

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

Function of smooth endoplasmic reticulum is?

  1. Synthesis of lipid

  2. Synthesis of minerals

  3. Synthesis of protein

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Its main functions are the synthesis of lipids, steroid hormones, the detoxification of harmful metabolic byproducts and the storage and metabolism of calcium ions within the cell. The smooth ER is distinguished from the other parts of the endoplasmic reticulum by the absence of membrane-bound ribosomes.

Thus A is the correct option.