The Structure of the DNA Molecule
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Adenine: A nitrogenous base. Pairs with thymine in DNA
Bacteriophage: A virus whose host is a bacterium. Also
Base: See nitrogenous
Base Pair: Two nitrogenous bases held together by weak
a DNA molecule adenine always pairs with thymine while cytosine
pairs with guanine. Thus, one DNA strand directs the synthesis of
other strand. This specificity of DNA base pairing is what enables
accurate replication of a DNA molecule.
Chromosome: a self-replicating genetic structure,
primarily of proteins and DNA, which carry nucleotide sequences
Complementary base pair: a pair of bases in which the
of one base defines the identity of its partner base. E.g.: In a
molecule there are two complementary base pairs--Adenine and
guanine and cytosine.
Cytosine: A nitrogenous base. Pairs with guanine in DNA
DNA (deoxyribonucleic acid): the molecule that encodes
information. DNA is composed of two anti-parallel strands which
a common axis to form a double helix. Each strand of DNA is
composed of a
linear array of nucleotides bonded in such a way that the bases
toward the central axis of the molecule while the two backbones
composed of alternating sugar and phosphate subunits. The bases of
strands are weakly bonded to each other in a complementary
other words, an adenine is always bound to a thymine while a
always bound to a guanine.
Gene: An ordered sequence of nucleotides which act as
functional subunit of hereditary information. The collection of
an organism determine the characteristics of that organism.
Guanine: A nitrogenous base. Pairs with cytosine in DNA
Meiosis: the process of cell division in which a single
produces four daughter cells each of which contains half of the
chromosomes of the parent cell. For example, a single diploid
spermatogonium (primordial germ cell) will divide meiotically to
haploid sperm cells.
Mitosis: the process of cell division in which a single
produces two daughter cells which are identical to on another, and
original parent cell.
Nitrogenous base: a molecule with
properties of a base, which also contains the element nitrogen.
Nucleic acid: a large molecule composed of repeating
Nucleotide: A subunit of DNA or RNA composed of a
base, a phosphate molecule, and a pentose sugar molecule.
Pentose sugar: A sugar molecule containing five carbon
Phage: A virus which infects a bacterial cell. Also
Purine: A nitrogen- containing, single ring compound
in nucleic acids. In DNA molecules, the purines are adenine and
Pyrimidine: A nitrogen containing, double ring compound
occurs in nucleic acids. In DNA molecules, the pyrimidines are
Radioactive phosphorus (32P): radioactive isotope of
element found in DNA molecules.
Radioactive sulfur (35S): radioactive isotope of 32S, an
found in proteins
T Phages: A phage which infects Escherichia coli. Viral
parasites of this type are labeled T1 through T7. T2 was the first
observed under the electron microscope.
Thymine: A nitrogenous base. Pairs with adenine in DNA
Virus: A particle consisting of a nucleic acid core
by a protein coat. New virus particles can only be produced by a
which is infected by the virus.