(MCDB) Introductory to Cellular & Molecular Biology; Mid term 2 Prep: Nucleic Acids
If nucleotides from the DNA of a human were quantified and 30 percent of them contained the base adenine, what percentage of them would contain the base guanine?
20 percent
If a DNA double helix contains 28% T nucleotides, then what is the percentage of A nucleotides?
28%
What would be the sequence of the strand of DNA that is made from the following template: 5′-ATCGAGCTA-3′ (Your answer must be written 5′ →→ 3′.)
5' TAGCTCGAT 3'
A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of _____.
120 thymine and 120 adenine molecules
What feature of single nucleotides provides the energy needed for polymerization when nucleic acids are formed?
their phosphate groups
n a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.
thymine ... cytosine
How would this sequence be different if RNA were made from this DNA template?
5' UAGCUCGAU 3'
What would be the sequence of the strand of DNA that is made from the following template: 5'-GATATCGAT-3'?
5'-ATCGATATC-3'
Identify the four bases in this RNA strand. What is the correct order of the base sequences, starting at the 5' end?
5'-UAGC-3'
If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence _____.
5'TGCAAT3'
How do the structures of RNA and DNA differ?
Adenine pairs with thymine in DNA, while adenine pairs with uracil in RNA.
How does the structure of DNA allow it to be copied?
After separating the strands of a DNA double helix, each template strand can be copied to make two identical DNA molecules
What is responsible for the increased stability of DNA compared to RNA?
DNA is a more stable molecule because it lacks a hydroxyl group on the 2' carbon.
What is responsible for the increased stability of DNA compared to RNA?
DNA is more resistant to cleavage because it lacks a hydroxyl group on the 2' carbon. DNA's secondary structure is more stable because of hydrophobic interactions and hydrogen bonds that form between complementary bases of the two sugar-phosphate backbones.
Which of the following describes the synthesis of nucleic acids?
Deoxyribonucleotides are added to the 3′3′ end of a DNADNA strand. Complementary pairing between bases is required for copying nucleic acids.
In a DNA double helix, what kind of chemical bonds form between the complementary nitrogenous bases?
Hydrogen bonds
Which symbol is generally used to represent a sugar in simple models of nucleotides?
Pentagon
Which of the following correctly describes nucleic acid synthesis?
Polymerization of nucleic acids occurs by the formation of phosphodiester bonds.
If 14C-labeled uracil is added to the growth medium of cells, what macromolecules will be labeled?
RNA
What is primarily responsible for the functional versatility observed in RNA?
Single-stranded RNA molecules will fold into different shapes based on interactions between their own bases.
If ADP (two phosphates) were hydrolyzed too AMP, how would you expect this reaction to compare with the hydrolysis of ATP to AMP?
The change in entropy would be less in the hydrolysis of ADP.
Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?
The phosphodiester linkages of the polynucleotide backbone would be broken.
What type of change occurs to a nucleotide when it is activated?
The potential energy of the molecule increases.
Single strands of nucleic acids are directional, meaning that there are two different ends. What functional groups define the two different ends of a strand?
a free hydroxyl group on the 3' carbon. a free phosphate group on the 5' carbon.
Which of the following includes all of the pyrimidines found in RNA or DNA?
cytosine, uracil, and thymine
In eukaryotic cells DNA has the appearance of a _____.
double helix
Large amounts of DNA typically wrap around large proteins called ________; this forms the ________ structure of DNA.
histones; tertiary
DNA is composed of building blocks called _____.
nucleotides
Some viruses consist only of a protein coat surrounding a nucleic acid core. If you wanted to radioactively label the nucleic acids separately from the protein, you would use radioactive _____.
phosphorus
