bio ch4
120 thymine and 120 adenine molecules
A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of
The charged phosphate groups and sugars of DNA are hydrophilic
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 phosphodiester bonds between deoxyribose sugars would be broken.
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
These numbers tell us there are ten rungs, or steps, on the DNA "ladder" for every turn of the helix.
Franklin and Wilkins analyzed DNA by bombarding DNA crystals with X-rays. Their analysis yielded two numbers that sparked interest, 3.4 nm and 0.34 nm. What is the significance of these numbers?
40
If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
Glucose
If cells are grown in a medium containing radioactive 32P-labeled phosphate, which of these molecules will be labeled?
The strands of the double helix are complementary.
In the context of chemical evolution, DNA's structure is interesting because it suggests a possible copying mechanism. What about DNA's structure facilitates copying?
nucleotides
Nucleic acids are polymers made up of which of the following monomers
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.
function in the synthesis of proteins
One of the primary functions of RNA molecules is to
If 14C-labeled uracil is added to the growth medium of cells, what macromolecules will be labeled?
RNA
Why do researchers think the first self-replicating molecule was RNA?
RNA can carry information and catalyze chemical reactions
Which of the following is a difference between RNA and DNA
RNA has ribose sugar and DNA has deoxyribose sugar
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
contains one less oxygen atom
The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA _____.
An RNA world could produce molecules that could self-replicate
The work of Bartel's group on the ribozyme RNA replicase supports which conclusion?
their phosphate groups
What feature of single nucleotides provides the energy needed for polymerization when nucleic acids are formed
Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit
What is the difference between a ribonucleotide and a deoxyribonucleotide
complementary pairing of the nitrogenous bases
What is the structural feature that allows DNA to replicate?
the sugar and the base
What is/are the variable structure(s) of a nucleotide
a covalent bond forms between the sugar of one nucleotide and the phosphate of a second
When nucleotides polymerize to form a nucleic acid
double antiparallel helical strands
Which of the following best describes DNA's secondary structure?
a nitrogenous base, a phosphate group, and a sugar
Which of the following descriptions best fits the class of molecules known as nucleotides
purines is always the same as pyrimidines
Which of the following did Watson and Crick already know when they were trying to determine the structure of DNA? The number of _____
cytosine, uracil, thymine
Which of the following includes all of the pyrimidines found in RNA and DNA
The sugar of RNA is much more reactive than the sugar of DNA
Why is it that RNA can catalyze reactions but DNA cannot?
The width of the double helix would vary along the length of the strand
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?
are information-containing molecules
both DNA and RNA
Which of the following are pyrimidine nitrogenous bases
cytosine and uracil
Which of the following are purine nitrogenous bases
guanine and adenine
Phosphorus
ome 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 _____.
