Question 1

The zinc atom at the centre of the zinc finger motif is held in place by which one of the following?&#10;A) Hydrogen bonds between the zinc atom and neighbouring amino acid side-chains&#10;B) Disulfide bonds between the zinc atom and neighbouring amino acid side-chains.&#10;C) Ionic bonds between the zinc atom and neighbouring amino acid side-chains.&#10;D) Coordinate bonds between the zinc atom and neighbouring amino acid side-chains.

Accepted Answer

The zinc atom in a zinc finger motif is coordinated by coordinate bonds, typically with cysteine and histidine residues, which stabilize the structure.

Question 2

Which of the following elements are classed as non-metals? Please select all that apply.&#10;A) Sulfur&#10;B) Iron&#10;C) Calcium&#10;D) Potassium&#10;E) Carbon

Accepted Answer

Sulfur and Carbon are non-metals.

Question 3

The endoplasmic reticulum is involved in the sequestering of which of the following metals to help mediate its role in cell signaling?&#10;A) Iron&#10;B) Sodium&#10;C) Potassium&#10;D) Calcium

Accepted Answer

The endoplasmic reticulum sequesters calcium ions, which play a crucial role in cell signaling pathways.

Question 4

Which of the following amino acids are most likely to participate the coordination of metals at the active site of an enzyme? Please select all that apply.&#10;A) Valine&#10;B) Proline&#10;C) Histidine&#10;D) Cysteine&#10;E) Asparagine

Accepted Answer

Histidine and cysteine are known for their ability to coordinate metal ions due to the presence of nitrogen in the imidazole ring of histidine and sulfur in the thiol group of cysteine, which can act as ligands.

Question 5

Which of the following statements correctly describe the behaviour of metals as components of metalloenzymes? Please select all that apply.&#10;A) The metal ions in a metalloenzyme may be coordinated to a variable number of atoms during the course of a reaction&#10;B) Metal ions in a metalloenzyme do not participate chemically in the reaction being catalyzed by the enzyme&#10;C) Metals are often located in the active site of metalloenzymes&#10;D) Metals in metalloenzymes may not obey the octet rule

Accepted Answer

Metal ions in metalloenzymes can change coordination numbers during reactions, are often found in active sites, and may not follow the octet rule due to their ability to form various coordination complexes.

Question 6

Which metal forms part of chlorophyll, the light-harvesting pigment found in the chloroplasts of plants?&#10;A) Zinc&#10;B) Copper&#10;C) Manganese&#10;D) Magnesium&#10;E) Iron

Accepted Answer

Magnesium is the central metal ion in the chlorophyll molecule, playing a crucial role in capturing light energy for photosynthesis.

Question 7

A metalloprotein may contain atoms of more than one metallic element.

Accepted Answer

Metalloproteins can have multiple metal ions as cofactors, which may include different types of metal elements.

Question 8

Elements whose characters fall partway between being a metal and a non-metal are called which of the following?&#10;A) Semi-metals&#10;B) Pseudo-metals&#10;C) Hemi-metals&#10;D) Metalloids&#10;E) Demi-metals

Accepted Answer

Elements that have properties intermediate between metals and non-metals are called metalloids.

Deck 11: Metals in Biology: Life Beyond Carbon