Question

Which of the following macromolecules are found in the plasma membrane?

• A. Proteins only
• B. Lipids and proteins only
• C. Proteins and carbohydrates only
• D. Lipids, proteins, and carbohydrates

Answer 1

The correct option is D Lipids, proteins, and carbohydrates

The plasma membrane needs lipids, which make a semi-permeable barrier between the cell and its environment. It also needs proteins, which are involved in cross-membrane transport and cell communication, and carbohydrates (sugars and sugar chains), which decorate both the proteins and lipids and help cells recognize each other.

1.) Proteins are the polymer of amino acids which are connected via peptide bond. Proteins account for more than 50% of the dry weight of most cells and make up about 15% by mass of our body. They are involved in structural support, storage, transport, signalling etc.

2.) Carbohydrates are the compounds of carbon, hydrogen and oxygen. They are the complex organic molecules that are broken down to release energy.

3.) Lipids are the hydrophobic compounds made up of carbon, hydrogen and oxygen. They act as reserve food material and store energy. They also act as insulation coats. Phospholipids which are a kind of lipids, are the major structural components of cell membranes.

So, the correct answer is "option B"