Structure of DNA and RNA Worksheet (Answers)

Structure of DNA and RNA Nucleic Acid Structure Draw the basic structure of a nucleotide, labelling its parts Differentiate between the different types of nitrogenous bases The four bases in DNA are: Guanine (G), Cytosine (C), Adenine (A) and Thymine (T) ………………………………………………………………………………………………………………………………………………….......... RNA has Uracil (U) instead of thymine ………………………………………………………………………………………………………………………………………………….......... G and A are double-ringed purines, while C, T and U are single-ringed pyrimidines ………………………………………………………………………………………………………………………………………………….......... G and C pair via three hydrogen bonds; A and T/U pair via two hydrogen bonds ………………………………………………………………………………………………………………………………………………….......... Compare the structure of DNA and RNA DNA RNA Sugar deoxyribose ribose Bases Has thymine (G, C, A, T) Has uracil (G, C, A, U) Double stranded Usually single stranded Strands List three types of RNA Messenger RNA (mRNA) - An RNA copy of a DNA gene 1. …………………………………………………………………………………………………………………………………………………... Transfer RNA (tRNA) - Transfers amino acids to the ribosome 2. …………………………………………………………………………………………………………………………………………………... Ribosomal RNA (rRNA) - The catalytic component of ribosomes 3. …………………………………………………………………………………………………………………………………………………... Outline, with the aid of the diagram, how nucleotides are linked together to form DNA strands • DNA nucleotides are linked by covalent phosphodiester bonds …………………………………………………………………………………………... (between the 5’-phosphate and 3’-hydroxyl of two nucleotides) …………………………………………………………………………………………... to form a long polynucleotide strand …………………………………………………………………………………………... • Two strands join together via complementary base pairing …………………………………………………………………………………………... (G pairs with C via 3 H bonds, A pairs with T via 2 H bonds) …………………………………………………………………………………………... • The two strands run antiparallel to each other in order for …………………………………………………………………………………………... the bases to face each other and form hydrogen bonds …………………………………………………………………………………………... • The double-stranded DNA then twists into a double helix …………………………………………………………………………………………... • Each twist occurs every ~10 nucleotides …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... List the contributions of the following scientists to the elucidation of DNA structure Linus Pauling: Identified molecular distances and bond angles for basic molecular structures ………………………………………………………………………………………………………………………... Phoebus Levene: Identified structure of a nucleotide (sugar, phosphate, base) ………………………………………………………………………………………………………………………... Erwin Chargaff: Determined that there is an equal number of purines and pyrimidines ………………………………………………………………………………………………………………………... Rosalind Franklin: Identified the organisation of DNA into a helical structure ………………………………………………………………………………………………………………………... Describe how Watson and Crick proposed the structure of DNA via model making Watson and Crick used the above knowledge and constructed DNA models through trial and error ………………………………………………………………………………………………………………………………………………….......... They demonstrated that DNA strands were antiparallel and formed a double helix ………………………………………………………………………………………………………………………………………………….......... They also showed complementary base pairing ………………………………………………………………………………………………………………………………………………….......... …………………………………………………………………………………………………………………………………………………..........