This set of Structural Biology Multiple Choice Questions & Answers (MCQs) focuses on “Ferritin”.
1. What kind of protein is ferritin?
a) Intercellular protein
b) Intracellular protein
c) Extracellular protein
d) Membrane protein
View Answer
Explanation: Ferritin is an intracellular protein that is present in tissues. It regulates the iron levels in the body and stores iron.
2. Which of the following features do not make ferritin genes highly conserved in humans?
a) Presence of three introns and four exons
b) Presence of four introns and three exons
c) Presence of three introns and three exons
d) Presence of four introns and four exons
View Answer
Explanation: Ferritin genes in humans have three introns between the 14th and 15th, 34th and 35th and 82nd and 83rd amino acid residues. At the ends of the exons, hundreds of untranslated bases are present.
3. Ferritin is a fibrous protein.
a) True
b) False
View Answer
Explanation: Ferritin is a globular protein, made up of 24 subunits. It is a globular protein because it stores protein, regulates the iron levels in case of excess production and deficiency.
4. The precursor for a functional ferritin molecule is _______
a) Cytosolic ferritin
b) Mitochondrial ferritin
c) Plasma ferritin
d) Reticuloendothelial ferritin
View Answer
Explanation: It is present in mitochondria as a metal binding protein, which on maturation assembles to form functional ferritin units.
5. In which form is iron stored in cells?
a) Heme
b) Ferritin
c) Free iron ions
d) Ferrous state
View Answer
Explanation: Ferritin is the form in which iron is stored as a non-toxic component, ready for transport. Free iron ions are toxic as they can form free radicals on reaction with dissolved oxygen. Apoferritin, a protein of the liver combines with ferrous ions and forms ferritin, which is iron in its ferric state.
6. How is iron stored in ferritin?
a) Fe ion in a spherical mold of ferritin
b) Fe ions along long chains of ferritin
c) Scattered Fe ions bound to ends of ferritin
d) Clusters of Fe ions along long chains of ferritin
View Answer
Explanation: Fe ions are taken up by ferritin and stored in the center of its hollow, spherical mold. Iron is stored in Fe-III oxidation state. When necessary, Fe is changed to Fe-II state and through channels in the spherical mold.
7. What are the types of iron release channels in ferritin?
a) Two-fold and three-fold channels
b) Two-fold and four-fold channels
c) Three-fold and four-fold channels
d) Two three-fold channels
View Answer
Explanation: Ferritin is a hollow spherical structure made up of 24 peptide subunits. Iron is stored in the middle and transported across the molecule via channels running through the structure. Three-fold channels are found at the intersection of three peptide subunits and four-fold channels are found at the intersection of four peptide subunits.
8. Which of the following properties is responsible for movement of iron ions in ferritin channels?
a) Electronegativity
b) Polarity
c) Solubility
d) Miscibility
View Answer
Explanation: Fe ions are transported in soluble Fe-II form via three-fold channels. The three-fold channels are lined with polar amino acid residues like aspartate and glutamate, which makes polar. When a positively charged Fe-II ion comes in close proximity to these channels, the resulting interactions facilitate the movement of Fe ions.
9. Fe ions are transported via the four-fold channels in ferritin.
a) True
b) False
View Answer
Explanation: The four-fold channels of ferritin are lined with non-polar amino acid residues like leucine, and hence is considered non-polar. Thus, when a Fe-II ion comes close, it does not interact with the four-fold channel unlike the three-fold channel, which is lined with polar groups. It was also found that four-fold channels are the sites for reduction of Fe-III to Fe-II.
10. Which of the following is not a function of ferritin?
a) Immune response
b) Control blood glucose level
c) Regulate blood iron level
d) Diagnostic purposes
View Answer
Explanation: Ferritin levels shoot up in cases of infections as an immediate response to endotoxins. It also acts as a buffer against low or high blood iron levels by storing it and releasing it when necessary. In diagnostics, the serum ferritin levels are checked because the amount of ferritin found directly relates to the amount of iron in the body.
Sanfoundry Global Education & Learning Series – Structural Biology.
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