Question

Directions: Answers must be in essay form. Outline form is not acceptable. Labeled diagrams may be used to supplement discussion, but in no case will a diagram alone suffice. It is important that you read each question completely before you begin.

Proteins–large complex molecules–are major building blocks of all living organisms. Discuss the following in relation to proteins:

A. The chemical composition and levels of structure of proteins

B. The roles of DNA and RNA in protein synthesis

C. The roles of proteins in membrane structure and transport of molecules across the membrane

Answer 1

A. The protein is made as a string from RNA i.e primary form,which is the simplest form of protein. The building block of protein is amino acid (caboxyl group,amino group, Hydrogen and R group). The amino acids are linked by peptide bond and forms a long and linear chain. After simple form, protein transforms into secondary, tertiary and qutarnary to protein.

B. Protein synthesis occurs at two sequential step: 1. Transcription 2. Translation.

Transcription is coding of RNA from DNA and translation is synthesizing protein from RNA. Soo for synthesis of protein RNA act as a messanger.

C. Various protein are found in the membrane to connect external and internal environment of the cell, transport of ions and molecules, etc.

Example : aquaporin, spectrin, integrin,etc.