Bio solution questions 1,2,3

Cardiac muscle relaxation is controlled by:

1. Intracellular potassium
2. Intracellular calcium
3. Myosin kinase
4. IP3 (inositol tris phosphate) channels
5. All of the above

Answer

• Intracellular calcium

Explanation:

Cardiac muscle relaxation is controlled by three systems: The intracellular calcium decline, thin filament deactivation, and cross-bridge cycling kinetics. As intracellular calcium decreases, the troponin dissociates from calcium which causes relaxation. Troponin is the component of thin filaments and is the main protein that regulates contraction and relaxation of muscles. When there is sufficient calcium, troponin binds with calcium to trigger production of muscular force, but when calcium declines, troponin is dissociated and hence muscle relaxation.

Question:

Why are RNA viruses exceptions to the Central Dogma?

Answer

• RNA viruses are exceptions to central dogma because they can form DNA using RNA template through a process called reverse transcription. Central dogma is where DNA forms RNA and then RNA forms protein and not backwards like in RNA viruses

Explanation:

Central dogma explains transfer of genetic information stored in DNA to messenger RNA using RNA polymerase by a process called transcription. Then, this messenger RNA is used to synthesize proteins. Therefore, the general process is DNA to RNA, and then RNA to Protein and not backwards. However, RNA viruses can form DNA using RNA by a process called Reverse transcription. This process is carried out by an enzyme called reverse transcriptase. Thus, this is an exception to the central dogma.

Question:

Why are bacterial capsules hard to stain?

Answer

• Bacterial capsules are difficult to stain because most stains cannot adhere to the capsule hence capsular materials with the stain are water-soluble and may be dislodged and removed when the stain is washed. The water-loving property of capsule makes it hard for differential staining.

Explanation:

Capsules are formed by organisms such as Klebsiella pneumoniae . Capsule is an important part of bacterial virulence because it enhances the ability of bacteria to cause infections, protecting the bacterial cell against removal and engulfment by the macrophages. It also plays a major role in helping the bacteria to adhere to tissues and cells. Staining the capsule is difficult because the stain can easily be washed away due to much water soluble content in capsule.