2017_Molecular-Techniques_STQ_QP

2017 Molecular Techniques STQ 2017 / H2 / ACJC PRELIM / P2 Q2 (CND, Stem Cells. Incl)2Recently, scientists discovered the presence of a population of bone-marrow derived stem cells that have the ability to form heart muscles cells when transferred to the heart. The stem cells were removed from the bone marrow and cultured so that they divided by mitosis. It was proposed that these stem cells resembled embryonic stem cells. (a)(i)Describe two similarities between these bone-marrow derived stem cells and embryonic stem cells.[2](ii)Describe how the rate of mitosis is controlled. [4](iii)State an advantage of using bone marrow derived stem cells rather than heart stem cells for the treatment of heart diseases.[1]

(c)Troponin is a protein that is integral to muscle contraction in heart muscles. Fig. 2.1 shows part of its DNA sequence. The entire sequence is 63 base pairs. Fig. 2.1PCR can be used to confirm presence of troponin DNA sequence. The following pair of primers are used.PrimerPrimer sequence15’ AATTCATGGGCATCG 3’25’ GAATTCTTAGTTACA 3’(i)In the boxed area in Fig. 2.1, circle and label the DNA sequences where Primers 1 and 2 will anneal.[1](ii)Explain how results of gel electrophoresis of the PCR products are able to show that troponin DNA has been successfully amplified.[1](iii)Besides the use of PCR, nucleic acid hybridisation can also be used to determine presence of troponin DNA.Outline how nucleic acid hybridisation can be used to identify troponin DNA.[4]

[Total: 13 marks]2017 / H2 / ACJC PRELIM / P2 Q4 (Mutations Incl)2Sickle cell anaemia is a recessive genetic disease caused by a mutation that commonly occurs in the DNA, resulting in hydrophobic valine replacing hydrophilic glutamic acid at the 6th amino acid position of the β chain.(a)State the type of mutation that commonly occurs to result in sickle cell anaemia. [1]______________________________________________________________________(b)Describe the effects of this change in amino acids on the red blood cells of an individual with the disease. [4]________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

To detect if individuals are afflicted with sickle cell anaemia, restriction fragment length polymorphism (RFLP) analysis can be carried out using gel electrophoresis and Southern Blotting. Restriction enzymes are used to digest the DNA before RFLP analysis and the mutation removes a recognition site of the restriction enzyme MstII, as shown in Fig. 4.1. The enzyme’s recognition sites