Tag: cell membrane

Questions Related to cell membrane

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

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

  1. Aminoacyl synthetase

  2. Acetyl CoA carboxylase

  3. Peptidyl transferase

  4. None of the above

Show answer
Correct Option: B
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.

The molting hormone ecdysone belongs to the category of

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

  1. Amines

  2. Long chain peptides

  3. Steroids

  4. Fatty acids

Show answer
Correct Option: C
Explanation:
Ecdysone is a steroidal prohormone of the major insect molting hormone 20-hydroxyecdysone, which is secreted from the prothoracic glands.

So, the correct answer is 'C'.

Consider the following fatty acids.
a. Stearic acid
b. Oleic acid
c. Linoleic acid
d. Linolenic acid
Which of these are found in plants?

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

  1. $1$ and $2$

  2. $1, 3$ and $4$

  3. $2, 3$ and $4$

  4. $1, 2, 3$ and $4$

Show answer
Correct Option: A

The plastids which are filled with a large amount of lipids are called.

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

  1. Etiolates

  2. Elastoplasts

  3. Leucoplasts

  4. Amyloplasts

Show answer
Correct Option: A

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

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

  1. Aleurites fordii

  2. Cocos nucifera

  3. Carthamus tinctorius

  4. Ricinus communis

Show answer
Correct Option: A

Cholesterol belongs to which of the following groups

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

  1. Steroids

  2. Neutral fats

  3. Waxes

  4. Phospholipids

Show answer
Correct Option: A
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'.

Which one of the following is not correctly matched?

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

  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

Show answer
Correct Option: A

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

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

  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

Show answer
Correct Option: B
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'.

In the fluid mosaic membrane model, the phospholipid bilayer

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

  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

Show answer
Correct Option: C
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'.

Function of smooth endoplasmic reticulum is?

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

  1. Synthesis of lipid

  2. Synthesis of minerals

  3. Synthesis of protein

  4. None

Show answer
Correct Option: A
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.