MB (ASCP) Review & Exam Questions Part I Well Answered!!

Which bases are purines? Which bases are pyrimidines? - Answer Adenine (A) and Guanine (G) are purines Cytosine (C) and Thymine (T) / Uracil (U) are pyrimidines What kind of structure do purines have? What kind of structure do pyrimidines have? - Answer purines have a double ring structure pyrimidines have a single ring structure The phosphate group in a nucleotide is expected to be found on which position of the sugar? - Answer 5th carbon The nitrogen base in a nucleotide is expected to be found on which position of the sugar? - Answer 1st carbon What is the sugar in DNA? What is the sugar in RNA? - Answer deoxyribose in DNA ribose in RNA Which nucleotides pair with each other? - Answer Guanine (G) and Cytosine (c) pair together Adenine (A) and Thymine (T) / Uracil (U) pair together Where do you find hydrogen bonds? - Answer they form between nucleotides on different strands A forms two bonds with T / U C forms three bonds with G Where do you find phosphodiester bonds? - Answer they form the backbone of DNA. There is a linkage between the 3' carbon of one sugar molecule and the 5' carbon atom of another Where do you find ionic bonds? - Answer they form the bond between DNA and histones. DNA is negatively charged and histones are positively charged Where do you find glycosidic bonds? - Answer they form the bond between the nitrogenous base and ribose sugar group in RNA What happens in a missense mutation? - Answer the altered codon now corresponds to a different amino acid. As a result an incorrect amino acid is inserted into the protein being synthesized What happens in a nonsense mutation? - Answer instead of tagging an amino acid, the altered codon signals for transcription to stop. Thus a shorter mRNA strand is produced and the resulting protein is truncated or nonfunctional What happens in a silent mutation? - Answer Since a few different codons can correspond to the same amino acid, sometimes a base substitution does not affect MB (ASCP)