Chapter 4 Flashcards
(17 cards)
Nucleotides are joined by a _____ to form the DNA and RNA polymers that function in the cell.
sugar-phosphate linkage
sugar-base-phosphate linkage
sugar-base linkage
base-phosphate linkage
sugar-phosphate linkage
All sugars found in nucleotides are _____.
pentoses
pyrimidines
purines
hexoses
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?
ribose
glucose
adenine
thymine
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 statement regarding complementary base pairing is correct?
The purine base cytosine (C) always pairs with the purine base guanine (G).
In DNA, the purine base adenine (A) always pairs with the pyrimidine base thymine (T).
Purines always pair with other purines, and pyrimidines always pair with other pyrimidines.
In DNA, the pairing of cytosine (C) with guanine (G) forms two hydrogen bonds.
In DNA, the purine base adenine (A) always pairs with the pyrimidine base thymine (T).
The secondary structure of DNA is due primarily to _____.
hydrogen bonding between complementary bases
ionic bonding between negatively charged phosphate groups and positively charged nitrogenous bases
hydrogen bonding between hydroxyl groups of the sugars and polar functional groups of the phosphate groups
phosphodiester bonds between sugar and phosphate groups of the backbone
hydrogen bonding between complementary bases
Which DNA sequence, written in the 5’ to 3’ orientation, is complementary to 5’ CATGGACTA 3’?
CATGGACTA
TAGTCCATG
AGTCCGTAC
GTACCTGAT
TAGTCCATG
Which of the following processes makes it possible for DNA to serve as a template for DNA synthesis and for RNA synthesis?
Complementary base pairing enables DNA to serve as a template.
There is a significant amount of energy in the phosphate groups, which drives these endergonic reactions.
Ribozymes are base repeats that make up the entire DNA or RNA molecule.
The strands of DNA are antiparallel.
Complementary base pairing enables DNA to serve as a template.
How are the structures of RNA and DNA similar?
The sugar molecule in both DNA and RNA is ribose.
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.
Adenine pairs with uracil in both.
In both, the –OH group on carbon 2 of ribose stabilizes the sugar molecule.
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?
The sugar-phosphate backbone of DNA is hydrophobic, whereas that of RNA is hydrophilic.
DNA has a sugar-phosphate backbone, whereas RNA has a sugar-sulfate backbone.
DNA is composed of nucleotides, whereas RNA is composed of amino acids.
DNA contains deoxyribose sugar, whereas RNA contains ribose.
DNA contains deoxyribose sugar, whereas RNA contains ribose.
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.
Tetrahymena
ribozymes
glycoproteins
enzymes
ribozymes
What is a major feature of the RNA world hypothesis?
Proteins carried information in the sequence of their amino acids in the first life-forms. These amino acids were translated into RNA base sequences.
The first life-forms probably had RNA as their unit of genetic information.
Once lipid membranes formed, cellular structures were present and could divide, forming additional life-forms.
Once a DNA molecule was formed from RNA, the first life-form was possible.
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?
electrophoresis
peptide
ligation
hydrolysis
ligation
Which of the following can both catalyze chemical reactions and carry information to copy itself?
proteins
lipids
RNA
DNA
RNA
Which statement correctly describes one aspect of the precise bonding between components of a nucleotide?
The phosphate group bonds to the 1′ carbon of sugar.
Nitrogen in the nitrogenous base bonds to the 1′ carbon of sugar.
Nitrogen in the nitrogenous base bonds to the phosphate group attached to the 5′ carbon of sugar.
Oxygen in the nitrogenous base bonds to the 1′ carbon of sugar.
Nitrogen in the nitrogenous base bonds to the 1′ carbon of sugar.
DNA is responsible for which attributes of life?
organisms
’
acquiring and using energy, and populations evolving
organisms
’
acquiring and using energy, and their being composed of cells
organisms
’
growing, and their being composed of cells
organisms
’
processing hereditary information, and replication
organisms’ processing hereditary information, and replication
The sequence of nitrogenous bases in an RNA and DNA strand is always written in the 5′ ? 3′ direction because _____.
each strand of RNA or DNA has an unlinked 3′ carbon and an unlinked 5′ carbon
nucleotides are added to the 5′ end of the nucleic acid
DNA and RNA are synthesized in this direction in cells.
DNA strands are antiparallel
DNA and RNA are synthesized in this direction in cells.
Which of these findings was determined by Watson and Crick as they explored the nature of the double helix structure of DNA?
Repeating distances between atoms in DNA molecules indicate a regular and repeating structure.
The two DNA strands are antiparallel.
For nitrogenous bases to fit within the helix structure, a purine must be interchangeable with any other purine.
The coiled sugar-phosphate backbone is arranged on the inside of the spiral.
The two DNA strands are antiparallel.
