Chapter 4 & 5 problem set
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
If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
40
5'-ATGC-3' with 5'-GCAT-3'
5'-ATGC-3' with 5'-GCAT-3'
Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?
5'-ATGC-3' with 5'-GCAT-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'
The name of the covalent bond that links monosaccharides together is a ____________.
Glycosidic linkage
All of the following are polysaccharides EXCEPT ________.
Lactose
Nucleic acids are polymers made up of which of the following monomers?
Nucleotides
Nucleic acids have a definite directionality. Stated another way, one end of the molecule is different from the other end. How are these ends described?
One end has an unlinked 3 carbon; the other end has an unlinked 5 carbon.
The following IS a structural polysaccharide:
Peptidoglycan
What is the difference between a ribonucleotide and a deoxyribonucleotide?
Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit.
DNA double helices are soluble in water but insoluble in alcohol. How do these physical properties reflect the chemical structure of the DNA molecule?
The charged phosphate groups and sugars of DNA are hydrophilic.
DNase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase?
The phosphodiester bonds between deoxyribose sugars would be broken.
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.
You have a polymer of DNA with 10 adenine bases followed by 10 cytosine bases. If that strand bonded to a strand of 20 thymine bases, how would the double helix shape vary from a typical DNA double helix?
The width of the double helix would vary along the length of the strand.
When nucleotides polymerize to form a nucleic acid _____.
a covalent bond forms between the sugar of one nucleotide and the phosphate of a second
Which of the following descriptions best fits the class of molecules known as nucleotides?
a nitrogenous base, a phosphate group, and a sugar
The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA _____.
contains one less oxygen atom
Which of the following are pyrimidine nitrogenous bases?
cytosine and uracil
Which of the following includes all of the pyrimidines found in RNA and DNA?
cytosine, uracil, and thymine
Which of the following best describes DNA's secondary structure?
double antiparallel helical strands
One of the primary functions of RNA molecules is to _____.
function in the synthesis of proteins
Which of the following are purine nitrogenous bases?
guanine and adenine
When cells are grown in a medium containing radioactive 32P-labeled phosphate, any molecules containing phosphate will end up being labeled with that radioactivity. Which of these molecules will be labeled with 32P?
nucleic acids
What is the structural feature that allows DNA to replicate?
omplementary pairing of the nitrogenous bases
Some viruses consist only of a protein coat surrounding a nucleic acid core. If you wanted to label the nucleic acids in a way that would distinguish them from protein, what element would you label?
phosphorus
Which of the following did Watson and Crick already know when they were trying to determine the structure of DNA? The number of _____.
purines is always the same as pyrimidines
What is the major structural difference between starch and glycogen?
the amount of branching that occurs in the molecule
What is/are the variable structures of a nucleotide?
the sugar and the base
