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4. Staphylococcus aureus (SA) is a common bacterium that is found on the skin and mucous membranes. It can cause a range of infections. Some strains of SA have developed resistance to the antibiotic methicillin, and are now known as methicillin-resistant Staphylococcus aureus (MRSA)  

1.1 A DNA strand has this sequence of bases. C  A  T  T  C  A  A  T  T  C  A  T  T  T  C      How many amino acids does this sequence of bases code for?   (1)

1.3 A student reads that DNA codons are non-overlapping. Suggest what is meant by the term non-overlapping. You should refer to the sequence of bases in your answer.   (2)

2.4.2 State the probability that the couple’s first child will have Treacher Collins syndrome (1)

  Question 3

2.4 Treacher Collins syndrome is characterised by deformed or missing bones in the face. It is thought to be transmitted by the dominant allele T. Sever forms of the syndrome can result in life-threatening breathing difficulties.     A Man with mild symptoms of Treacher Collins syndrome is heterozygous for the gene. His wife does not have the syndrome. Before deciding whether to have children, the couple wishes to know what the probability is of their child inheriting the condition.     Complete the Punnet square to show the genotypes and the gametes of the couple, and the possible genotypes and the phenotypes of their children. Use T and t to represent the alleles. (3)   [MaleGenotype] [WifeGenotype] [i] [ii] [iii] [iv]    

What kind of software do you use to do your math assignment?

4. Staphylococcus aureus (SA) is a common bacterium that is found on the skin and mucous membranes. It can cause a range of infections. Some strains of SA have developed resistance to the antibiotic methicillin, and are now known as methicillin-resistant Staphylococcus aureus (MRSA)  

3.2 Explain how mutations can increase variation in a species (3)

2.4.2 State the probability that the couple’s first child will have Treacher Collins syndrome (1)