Chapter 4: Nucleic Acids and the RNA world Flashcards
Nucleotides are joined by a \_\_\_\_\_ to form the DNA and RNA polymers that function in the cell. a) sugar–phosphate linkage b )sugar–base linkage c) sugar–base–phosphate linkage d) base–phosphate linkage
a) sugar–phosphate linkage
All sugars found in nucleotides are _____.
a) purines
b) pyrimidines
c) hexoses
d) pentoses
d) pentoses
In order for nucleotides to form in the prebiotic soup, which sugar in the following list would have had to be present in abundant quantities?
a) ribose
b) thymine
c) adenine
d) glucose
a) ribose
Complementary base pairing explained Chargaff’s findings—the fact that the number of cytosines in a DNA sample equals the number of guanines, and the number of thymines equals the number of adenines. Complementary base pairing is the formation of hydrogen bonds between antiparallel strands of the DNA molecule. Which one of the following statements regarding complementary base pairing is correct?
a) Purines always pair with other purines, and pyrimidines always pair with other pyrimidines.
b) In DNA, the purine base adenine (A) always pairs with the pyrimidine base thymine (T).
c) The purine base cytosine (C) always pairs with the purine base guanine (G).
d) In DNA, the pairing of cytosine (C) with guanine (G) forms two hydrogen bonds.
b) In DNA, the purine base adenine (A) always pairs with the pyrimidine base thymine (T).
Which DNA sequence, written in the 5′ to 3′ orientation, is complementary to 5′ CATGGACTA 3′?
A) TAGTCCATG
B) GTACCTGAT
C) AGTCCGTAC
D) CATGGACTA
A) TAGTCCATG
Which of the following processes makes it possible for DNA to serve as a template for DNA synthesis and for RNA synthesis?
A) Complementary base pairing enables DNA to serve as a template.
B) There is a significant amount of energy in the phosphate groups, which drives these endergonic reactions.
C) Ribozymes are base repeats that make up the entire DNA or RNA molecule.
D) The strands of DNA are antiparallel.
A) Complementary base pairing enables DNA to serve as a template.
How are the structures of RNA and DNA similar?
A) In both, the —OH group on carbon 2 of ribose stabilizes the sugar molecule.
B) Adenine pairs with uracil in both.
C) Their sugar-phosphate backbones are formed by phosphodiester linkages between the phosphate group of one nucleotide and the hydroxyl group on the sugar of the adjacent nucleotide.
D) The sugar molecule in both DNA and RNA is ribose.
C) Their sugar-phosphate backbones are formed by phosphodiester linkages between the phosphate group of one nucleotide and the hydroxyl group on the sugar of the adjacent nucleotide.
In which of the following ways does DNA differ from RNA?
A) DNA has a sugar–phosphate backbone, whereas RNA has a sugar–sulfate backbone.
B) DNA is composed of nucleotides, whereas RNA is composed of amino acids.
C) The sugar–phosphate backbone of DNA is hydrophobic, whereas that of RNA is hydrophilic.
D) DNA contains deoxyribose sugar, whereas RNA contains ribose.
D) DNA contains deoxyribose sugar, whereas RNA contains ribose.
Due to complementary base pairing, RNA molecules form secondary structure. What is the type of RNA secondary structure associated with an open loop and a stem created by complementary base pairing?
A) ribozymes
B) transfer RNA
C) ligated RNA
D) hairpin loops
D) hairpin loops
Scientists recognized that in order to obtain evidence that life arose spontaneously at some point in history, they needed to find a molecule that was capable of carrying/storing information and capable of self-replication. One piece of evidence critical in proposing the RNA world hypothesis was the discovery of _____ by Sidney Altman and Thomas Cech.
A) enzymes
B) ribozymes
C) glycoproteins
D) Tetrahymena
B) ribozymes
What is a major feature of the RNA world hypothesis?
A) Proteins carried information in the sequence of their amino acids in the first life-forms. These amino acids were translated into RNA base sequences.
B) Once a DNA molecule was formed from RNA, the first life-form was possible.
C) The first life-forms probably had RNA as their unit of genetic information.
D) Once lipid membranes formed, cellular structures were present and could divide, forming additional life-forms.
C) The first life-forms probably had RNA as their unit of genetic information.
Bartel and Szostak demonstrated that RNA can catalyze what type of reaction that results in the joining of two RNA molecules together?
A) peptide
B) electrophoresis
C) hydrolysis
D) ligation
D) ligation
Which of the following can both catalyze chemical reactions and carry information to copy itself?
A) proteins
B) RNA
C) lipids
D) DNA
B) RNA
Which statement correctly describes one aspect of the precise bonding between components of a nucleotide?
A) Oxygen in the nitrogenous base bonds to the 1′ carbon of sugar.
B) Nitrogen in the nitrogenous base bonds to the 1′ carbon of sugar.
C) Nitrogen in the nitrogenous base bonds to the phosphate group attached to the 5′ carbon of sugar.
D) The phosphate group bonds to the 1′ carbon of sugar.
B) Nitrogen in the nitrogenous base bonds to the 1′ carbon of sugar.
DNA is responsible for which attributes of life?
A) organisms’ acquiring and using energy, and their being composed of cells
B) organisms’ processing hereditary information, and replication
C) organisms’ acquiring and using energy, and populations evolving
D) organisms’ growing, and their being composed of cells
B) organisms’ processing hereditary information, and replication
