Chapter 4 Biology
Refer to Nakano's quote from Science. If the cytosine is positively charged (+) before self- cleavage, what would its charge be after self-cleavage?
- (negative)
15) If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
40
Which of the following are pyrimidine nitrogenous bases?
B) cytosine and uracil
Which of the following descriptions best fits the class of molecules known as nucleotides?
a nitrogenous base, a phosphate group, and a sugar
Both DNA and RNA _____.
are information-containing molecules
Which of the following best describes DNA & #39;s secondary structure?
double antiparallel helical strands
If cells are grown in a medium containing radioactive 32P-labeled phosphate, which of these molecules will be labeled?
glucose
Which of the following are purine nitrogenous bases?
guanine and adenine
Nucleic acids are polymers made up of which of the following monomers?
nucleotides
What is/are the variable structure(s) of a nucleotide?
the sugar and the base
What feature of single nucleotides provides the energy needed for polymerization when nucleic acids are formed?
their phosphate groups
One of the primary functions of RNA molecules is to _____.
transmit genetic information to offspring function in the synthesis of proteins
What is the structural feature that allows DNA to replicate?
complementary pairing of the nitrogenous bases
The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA _____.
contains one less oxygen atoms
Which of the following includes all of the pyrimidines found in RNA and DNA?
cytosine, uracil, and thymine
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
Nucleic acids have a definite polarity, or 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.
Which of the following is a difference between RNA and DNA?
RNA has ribose sugar and DNA has deoxyribose sugar.
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.
DNAase 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.
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
In the acid-base reaction described in the preceding paragraph about Nakano's research on RNAs, a proton (H+) is being transferred. What is acting as the proton acceptor?
magnesium hydroxide
Which of the following chemical bonds do you think Nakano is referring to in his quote?
phosphodiester
6) 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
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
