The answer is D. Iodine is used to test for starches and, in the presence of a starch, it will turn a dark blue-black color.
The S<span>canning Electron Microscope or SEM shows in 3D </span>
Answer:
The correct answer is: d. progressive stabilisation of correct secondary structural intermediates, and unfolding of incorrect structures, until the final structure is attained.
Explanation:
- Protein folding is a sequential process and not a random one.
- It is necessary that a protein must fold in such a way that in the end it is able to attain the particular conformation which is required for its function.
- The folding of an amino acid sequence is a process that is thermodynamically favourable.
- This is because in a folded protein the hydrophobic amino acids escapes from interacting with water molecules and hence gets stabilised.
- A folded protein has lower energy and is more stable than a linear polypeptide chain.
- The folding of an amino acid linear chain into a protein takes place in the following way:
- The folding of the amino acid sequence begins during the process of translation of the mRNA (messenger Ribonucleic Acid) by Ribosome. (Co-translational folding)
- This is because initially the linear amino acid sequence forms a secondary structure (alpha helix, beta sheet) which is formed between the nearby amino acid residues.
- These structures form progressively and sequentially and each structure after formation is checked for its correct conformation before the next structure (tertiary structure) is formed.
- If an incorrect folding has occurred, the folded polypeptide chain opens up and refolds until correct orientation is attained.
- Folding, opening and refolding process continues until the correct conformation of the protein is attained.
