Chapter 9: DNA Structure and Analysis Flashcards
What are the four major characteristics of the genetic material?
- Replication
- Storage of information
- Expression of information
- Variation by mutation
Once the genetic material of cells replicates and is doubled in amount, it must then be partitioned equally into daughter cells. This characteristic is referred to as?
Replication
Requires the molecule to act as a repository of genetic information that may or may not be expressed by the cell in which it resides. This characteristic is referred to as?
Storage of information
As a basis of the process of information flow within the cell. This characteristic is referred to as?
Expression of information
The chemical information in mRNA directs the construction of a chain of amino acids, called a polypeptide, which then folds into a protein. This process is called?
Translation
What are the three main types of RNA molecules that are synthesized?
- mRNA
- rRNA
- tTNA
Mutations/ alterations may be reflected during transcription and translation, affecting the specific protein. This characteristic is referred to as?
Variation by mutation
The Swiss chemist, Friedrich Miescher called the DNA what?
Nuclein
DNA contained approximately equal amounts of four similar molecules called nucleotides. This hypothesis is referred to as?
tetranucleotide hypothesis of DNA
Strain of Streptococcus pneumoniae that possess the polysaccharide coat, are not easily engulfed; they multiply and cause pneumonia. They form smooth colonies (S) with a shiny surface when grown on an agar culture plate
Virulent strain
The nonencapsulated strain of Streptococcus pneumoniae that are readily engulfed and destroyed by phagocytic cells in the animal’s circulatory system. It produces rough colonies (R).
Avirulent strain
Each strain of Diplococcus may be one of the dozens of different types called?
Serotypes
These structures (cells) whose cell wall has been removed are called?
Protoplast (or spheroplasts)
Process of infection by only the viral nucleic acid.
Transfection
True or False. RNA serves as the genetic material in some viruses.
True
An enzyme derived from E. coli cells that replicates RNA upon infection of RNA virus.
RNA replicase
RNA serves as a template for the synthesis of the complementary DNA molecule.
Reverse transcription
Reverse transcription is directed by what enzyme?
Reverse transcriptase
True or False. James Watson and Francis Crick proposed that the structure of DNA is in the form of a single helix.
False. Double helix
The building blocks of all nucleic acid molecules.
Nucleotides
Nucleotides are made of:
- Nitrogenous base (A, G, C, G, U)
- Pentose sugar (deoxyribose or ribose)
- Phosphate group
True or False. Both DNA and RNA contain A, G, and C, but only DNA contains the base T and only RNA contains the base U.
True
What are the two kinds of nitrogenous bases?
- nine-member double-ring purine (Adenine and Guanine)
2. six-member single-ring pyrimidines (Cytosine, Thymine, Uracil)
Two kinds of pentose sugar.
Ribose (RNA) and deoxyribose (DNA)
A pentose sugar that has a hydroxyl group present on the C-2’ position.
Ribose sugar
Ribose sugar that has a hydrogen atom rather than a hydroxyl group present at the (C-2′) position.
Deoxyribose (2-deoxyribose)
A molecule that is composed of a purine or pyrimidine base and a ribose or deoxyribose sugar.
Nucleoside
This molecule is produced if a phosphate group is added to the nucleoside.
Nucleotide
What carbon of the ribose sugar participates in the bonding with the nitrogen base?
C-1’
If the base is purine, what atom of the nitrogen base binds to the C-1’ of the ribose sugar?
N-9 atom
If the base is pyrimidine, what atom of the nitrogen base binds to the C-1’ of the ribose sugar?
N-1 atom
Which carbon on the ribose sugar may the phosphate group be bonded with?
(C-2′), (C-3′), or (C-5′)
Which ribose-phosphate bonding configuration is the most biologically significant?
(C-5′) - phosphate configuration
The precursor nucleotide molecule during nucleic acid synthesis within the cell.
nucleoside trisphosphate
The linkage between two mononucleotides involves a phosphate group linked to two sugars. This bond is called?
3’ to 5’ phosphodiester bond
True or False. The amount of adenine residues is proportional to the amount of thymine residues in DNA and the amount of guanine residues is proportional to the amount of cytosine residues.
True
True or False. The percentage of (G + C) does not necessarily equal the percentage of (A + T). Instead, this ratio varies greatly between different organisms.
True
Two long polynucleotide chains are coiled around a central axis, forming what structure?
Right-handed double helix.
True or False. 2. The two chains are parallel; that is, their (C-5′) to (C-3′) orientations run in the same directions.
False. antiparallel; opposite direction
True or False. The bases of both chains are flat structures, lying perpendicular to the axis; they are “stacked” on one another 4 Å (0.34 nm) apart, and located on the inside of the structure.
True
True or False. The nitrogenous bases of opposite chains are paired as the result of ionic bonds; in DNA, only A-T and G - C pairs occur.
False. Hydrogen bonds
Each complete turn of the helix is 34 Å (3.4 nm) long; thus, 10 bases exist per turn in each chain.
True (but further and more sophisticated studies suggest that each complete turn of the helix involves 10.4 bases)
Size of the double helix?
2 nm
True or False. In any segment of the molecule, alternating larger major grooves and smaller minor grooves are apparent along the axis.
True
Chemical affinity provided by hydrogen bonding between the bases provides what between corresponding bases?
Complementarity
A very weak electrostatic attraction between a covalently bonded hydrogen atom and an atom with an unshared electron pair.
Hydrogen bonds
Which atom among the hydrogen bond participating atoms assumes a partial positive charge?
hydrogen atom
Which atom among the hydrogen bond participating atoms assumes a partial negative charge?
covalently bonded oxygen or nitrogen atoms
How many hydrogen bonds does adenine form with thymine?
Two H bonds
How many hydrogen bonds does guanine form with cytosine?
Three H bonds
True or False. Two or three individual hydrogen bonds are energetically very weak, 2000 to 3000 bonds in tandem (typical of two long polynucleotide chains) provide great stability to the helix.
True
Nitrogenous bases are _____. For that reason, they are being shielded on the interior of the DNA axis.
Hydrophobic
Sugar–phosphate backbones are ______. For that reason, they are situated on the outside of the axis, where both components can interact with water.
Hydrophilic
This type of DNA is prevalent under high-salt or dehydration conditions. It is slightly more compact, with 11 base pairs in each complete turn of the helix, which is 23 Å (2.3 nm) in diameter.
A-DNA (right-handed)
This type of DNA is present under aqueous, low-salt conditions and is believed to be the biologically significant conformation.
B-DNA (right-handed)
This type of DNA is a left-handed helix, 18 Å (1.8 nm) in diameter, contains 12 bp per turn, and assumes a zigzag conformation (hence its name). The major groove present in B-DNA is nearly eliminated.
Z-DNA (left-handed)
This type of DNA is produced by artificial “stretching” of DNA, creating a longer, narrower version with the phosphate groups on the interior.
P-DNA
Generally the largest (based on Svedberg coefficient) of all RNA molecules and usually constitute about 80 percent of all RNA. Is an important structural component of ribosomes, which function as nonspecific workbenches where proteins are synthesized during translation.
rRNA
An RNA that carries genetic information from the DNA of the gene to the ribosome.
mRNA
An RNA that carries amino acids to the ribosome during translation
rRNA
An RNA that is involved in DNA replication at the ends of chromosomes (the telomeres).
telomerase RNA
An RNA that participates in processing mRNAs.
small nuclear RNA (snRNA)
This measure depends on a molecule’s density, mass, and shape, and its measure. It may also be used to quantify the sedimentation behavior of RNAs in a centrifugal field.
Svedberg coefficient
In this analytical technique, DNA is subjected to heat, the double helix is denatured and unwinds. During unwinding, the viscosity of DNA decreases and UV absorption increases.
Hyperchromic shift
In this temperature, 50 percent of the strands have already unwound.
Melting temperature
True or False. S values almost always designate molecules of greater molecular weight, the correlation is direct; that is, a two-fold increase in molecular weight does not lead to a two-fold increase in S.
False. Not direct
True or False. The molecule with a higher Tm has a higher percentage of G-C base pairs than A-T base pairs since G-C pairs share three hydrogen bonds compared to the two bonds between A-T pairs.
True
