Portage Learning Chem 210 - Module 4 Problem Set

Portage Learning Chem 210 - Module 6 Problem Set What is the difference between a nucleoside and nucleotide? A nucleoside is formed from the covalent bonding of a base, purine or pyrimidine, to either ribose or 2-deoxyribose. Nucleotides are built from a nitrogen-containing organic base, a monosaccharide, and phosphate. What characteristic makes purines and pyrimidine heterocyclic? Each has a ring with nitrogen in the ring instead of all carbon atoms in the ring. Is this molecule ribose or 2-deoxyribose? Briefly explain what structural information was used to determine this. Ribose. This molecule contains an -OH on carbon 2. 2-deoxyribose has an -H atom on the second carbon. Question 4 Is the following a pyrimidine or purine? Provide the name and one-letter symbol. Pyrimidine. It is thymine (T). What is the difference between thymine and uracil? These two bases differ by a methyl group. Thymine has an extra methyl group on the ring. From the course and module information, where in a eukaryotic or prokaryotic cell, is the DNA located? How about the RNA? DNA is located in the nucleus of a eukaryotic cell or the nucleoid of a prokaryotic cell. RNA is found in the nucleus, on the ribosome, and in other parts of the cell. Which DNA and RNA bases contain a carbonyl group? Guanine, cytosine, thymine, and uracil all contain C=O group attached to the rings. Adenine is the only base that does not. What constitutes the backbone of DNA? In DNA, this consists of the alternating deoxyribose and phosphate groups linked together through covalent bonds (Figure 6.6). How many hydrogen bonds form between A and T? Two hydrogen bonds are formed between these two bases. G and C form three H-bonds. Which nucleic acid is single-stranded? RNA. RNA forms single strands. Particularly this was noted in this module for tRNA. DNA forms a double helix. What interactions stabilize the DNA double helix? Hydrogen bonds stabilize the helix. Each AT pair and form two hydrogen bonds, and each GC pair forms three hydrogens that stabilize the helix, permitting it to maintain this shape. What type of RNA has a sequence that is complementary to DNA? mRNA is complementary so that it can transmit the information to the ribosome. Which has the largest molecular weight chains: mRNA, tRNA, or rRNA? rRNA. These molecules make up ribosomes. What structural forms of DNA have a right-handed helix? Which form has a left-handed helix? The A- and B-forms are right-handed, while the Z-form is left-handed. What function does cAMP perform in cells? cAMP is a communication molecule in cellular signaling. It acts as a secondary messenger.