Homework M3.3: Nucleic acids
What distinguishes nucleotides from nucleosides?
Nucleosides lack the phosphate group
Nucleic acids have a definite polarity, or directionality. Stated another way, one end of the molecule is different from the other end. Why?
One end has an unlinked 3' carbon; the other end has an unlinked 5' carbon.
Which of the following is not a difference between RNA and DNA?
One is made of nucleotide monomers and the other one is not.
Which of the following groups is not found in nucleosides?
Phosphates
Which of the following bases is not foundin RNA?
T
Which of the following statements about the 5' end of a polynucleotide strand of DNA is correct?
The 5' end has a phosphate group attached to the number 5 carbon of ribose.
Which of the following statements is true for double-stranded DNA?
The amount of A is the same as the amount of T, and the amount of G is the same as the amount of C.
DNA is water soluble because:
The exterior-facing sugar-phosphate backbones are negatively charged and hydrophilic.
The Tm for melting the double helix is:
The midpoint of the range over which the helix denatures.
Match the type of RNA with its function in eukaryotic cells.
__4__participates in splicing, a form of processing, of other RNAs __1__carries information from genes in the sequence of its nucleotides in order to make proteins __3__used as to help structure and hold proteins in the ribosome __5__controls gene expression by degrading other RNAs or blocking protein production __2__ transports amino acids to the ribosome 1.mRNA 2.tRNA 3.rRNA 4.snRNA 5.microRNA (miRNA)
Either strand of a DNA molecule can be used as a template to reconstruct the other because the two strands of a DNA molecule are:
complementary
Which of the following best describes DNA's secondary structure?
double antiparallel helical strands
Supercoiling of DNA
requires the action of topoisomerase enzymes in cells
Topoisomerases are associated with
supercoiling of DNA.
Nucleotides have a nitrogenous base attached at which carbon atom of the sugar?
2'
Which is the dominant form of DNA found in the cell?
B
RNA is hydrolyzed (or broken apart) in basic solution, but DNA is not. This occurs because
DNA contains 2'-deoxyribose, but RNA does not
Above is a Haworth projection of ribose. In a nucleotide, many of the carbons are attached to a different functional group. Match the functional groups below to which carbon they attach to on ribose when forming a nucleotide.
(3) 3' (1) 5' (4)_ 4' (3)_. 2' (2) 1' 1.phosphate group 2.nitrogenous base 3.hydroxyl 4.blank / no functional group
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.
Consider a fragment of DNA that has a total of eight bases. Five of these are adenines and three are cytosines. How many hydrogen bonds would there be in this fragment between purine/pyrimidine pairs?
19
The DNA sequence capable of pairing with 5' CGATTAGT 3' is:
3' GCTAATCA 5'
If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
40
Nucleotides have a phosphate group attached at which carbon atom of the sugar?
5'
If one strand of a DNA molecule has the sequence of bases 5'ATTGCA3', the other complementary strand would have the sequence
5'TAACGT3
Which piece of DNA will have the higher Tm, one with a cytosine plus guanine content of 30% or one with a cytosine plus guanine content of 50% if both are heated under the same experimental conditions?
50% cytosine plus guanine will have the higher Tm.
In an analysis of the nucleotide composition of DNA, which of the following will be found?
A + C = G + T
If 14C-labeled uridine triphosphate (UTP) is added to the growth medium of cells, what macromolecules will be labeled?
RNA
Which of the following descriptions best fits the class of molecules known as nucleotides?
a nitrogenous base, a phosphate group, and a pentose sugar
The backbone of nucleic acids consists of
a phosphodiester bond between the 3' and 5' hydroxyl groups of neighboring sugars
The fundamental differences between RNA and DNA are
bases and the ribose units only
Match the bond/force with the correct description in nucleic acid structure.
bond that connects two monomers (nucleotides) into a polymer (nucleic acid) - covalent bond bond that allows A to pair with T - hydrogen bond bond that connect ribose sugar with nitrogenous base in a nucleotide - covalent bond interaction of ribose in water -hydrogen bond bond that holds DNA strands together in a double helix - hydrogen bond
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 nitrogenous bases of the pyrimidine type?
cytosine and uracil
RNA has a more stable structure than DNA
false
Which of the following nucleobases is a purine?
guanine
The strands in the double helix
have their 3' → 5' directions opposed, i.e., they are anti-parallel
What is responsible for holding the two strands together in the DNA double helix?
hydrogen bonds
Which force holds the two anti-parallel strands of DNA together in a double helix?
hydrogen bonds
Which macromolecule stores the most energy per gram?
lipids
What type of RNA is involved in delivery of amino acids to a growing polypeptide chain?
mRNA
The types of bonds linking neighboring nucleotides together in a nucleic acid is called
phosphodiester bonds.
The nucleotide sequence of DNA is which level of structure?
primary
What is the difference between a ribonucleotide and a deoxyribonucleotide?
ribonucleotides have a hydroxyl group on the 2' carbon of their sugar subunit.
Hairpins and stem-and-loop patterns make up what part of RNA's structure?
secondary
What dictates the primary structure of a nucleic acid?
the sequence of bases
