11.3. Some reactions of the halide ions
A subsection of Chemistry, 9701, through 11. Group 17
Listing 10 of 171 questions
Whilst small amounts of some metal ions are vital in the human body, others can be highly toxic. Hg2+ ions are toxic for a number of reasons. Hg2+ ions can react with the R–S–S–R group, which is found in proteins. R–S–S–R + 2Hg2+ + H2 2 R–S–Hg+ + 2H+ reaction 1 What is the name of the R–S–S–R group in proteins? Which level of protein structure will be affected by reaction 1? Why will this affect the activity of an enzyme? Ag+ ions can combine with free –COOH groups in the side chains of the amino acid residues in proteins to form partially covalent silver carboxylates. RCOOH + Ag+ RCOOAg + H+ reaction 2 What type of behaviour is the –COOH group showing in reaction 2? What types of R group interactions will be affected by reaction 2? Explain your answer. By contrast, iron is an extremely important metal used in haemoglobin to transport oxygen molecules from the lungs to muscle cells and to carry carbon dioxide in the reverse direction. One haemoglobin molecule contains four haem groups, each of which contains one iron atom. In the haem group four nitrogen atoms are in the same plane as the iron atom. The oxygen molecule is attached above this plane, and the iron atom is joined to a protein chain below this plane. H C Fe C H haem CH2 CH3 CH2 CH3 H3C H3C HOOC COOH N N N HC CH N How many oxygen atoms could one haemoglobin molecule transport? By what type of bonding is the oxygen molecule likely to be held to the iron atom in haem? What is the geometry of bonding around the iron atom?
9701_w10_qp_41
THEORY
2010
Paper 4, Variant 1
View
Whilst small amounts of some metal ions are vital in the human body, others can be highly toxic. Hg2+ ions are toxic for a number of reasons. Hg2+ ions can react with the R–S–S–R group, which is found in proteins. R–S–S–R + 2Hg2+ + H2 2 R–S–Hg+ + 2H+ reaction 1 What is the name of the R–S–S–R group in proteins? Which level of protein structure will be affected by reaction 1? Why will this affect the activity of an enzyme? Ag+ ions can combine with free –COOH groups in the side chains of the amino acid residues in proteins to form partially covalent silver carboxylates. RCOOH + Ag+ RCOOAg + H+ reaction 2 What type of behaviour is the –COOH group showing in reaction 2? What types of R group interactions will be affected by reaction 2? Explain your answer. By contrast, iron is an extremely important metal used in haemoglobin to transport oxygen molecules from the lungs to muscle cells and to carry carbon dioxide in the reverse direction. One haemoglobin molecule contains four haem groups, each of which contains one iron atom. In the haem group four nitrogen atoms are in the same plane as the iron atom. The oxygen molecule is attached above this plane, and the iron atom is joined to a protein chain below this plane. H C Fe C H haem CH2 CH3 CH2 CH3 H3C H3C HOOC COOH N N N HC CH N How many oxygen atoms could one haemoglobin molecule transport? By what type of bonding is the oxygen molecule likely to be held to the iron atom in haem? What is the geometry of bonding around the iron atom?
9701_w10_qp_42
THEORY
2010
Paper 4, Variant 2
View
Questions Discovered
171