BIO101 Unit 12
The Molecular Basis of Life: DNA Replication,
Protein Synthesis & Mitosis
Glossary
adenine(A)
One of the five nitrogen bases in the nucleotides composing the structure of DNA and RNA;
pairs with thymine in DNA and uracil in RNA.
anaphase
a phase of mitosis after metaphase where the chromosomes are pulled apart by the spindle fibers
anticodon
a three nucleotide base code in tRNA which pairs with the complementary opposite codon of
mRNA.
cell plate
The type of cytokinesis which occurs in plant cells; a new cell wall begins to develop in the
middle of the cell growing towards the outside resulting in the formation of two new daughter
cells.
cleavage furrow
The type of cytokinesis which occurs in animal cells; a pinching in of the cell membrane
resulting in the formation of two new daughter cells.
codon
three-base sequence in messenger RNA that causes the placing of a particular amino acid during
the directed development of a specific into a protein molecule during the process called
translation.
cytokinesis
the division of the cytoplasm of a cell which occurs during telophase of mitosis.
cytosine (C)
one of the five nitrogen bases found in the nucleotides composing the structure of DNA and
RNA; pairs with guanine.
deoxyribose
the pentose sugar which is a structural part of the nucleotides of DNA.
DNA
Deoxyribose nucleic acid; nucleic acid found in cells; the genetic material that specifies protein
synthesis in cells.
DNA replication
A molecular reproduction process in cells which results in an exact copy of DNA being
produced; occurs during chromosome duplication just prior to the cell dividing..
guanine (G)
one of the five nitrogen bases in the nucleotides composing the structure of DNA and RNA; pairs
with cytosine.
interphase
a phase of mitosis when the cell is carrying on normal activities; DNA replication occurs during
this phase just prior to the cell dividing.
messenger RNA (mRNA)
Ribose nucleic acid molecules whose sequence of codons specifies the sequence of amino acids
during protein synthesis; mRNA is made by the process of transcription.
metaphase
a middle phase of mitosis where the chromosomes line up along the equator of the cell.
mitosis
type of cell division in which daughter cells receive the exact chromosome and genetic makeup
of the parent cell; occurs during growth and repair.
molecular reproduction
the production of molecules in living cells.
polynucleotide
polymer of many nucleotides bonded together in molecules such as DNA and RNA.
prophase
a phase of mitosis when the chromosomes appear as sister chromatids and the spindle fibers of
asters appear.
protein synthesis
occurs when gene activity leads to the production of a specific protein by a cell..
purine
nitrogen base which has a double ring of carbon and nitrogen atoms; adenine and guanine.
pyrimidine
nitrogen base which has a single ring composed of carbon and nitrogen atoms; cytosine, thymine,
and uracil.
ribose
the pentose sugar found in the nucleotides of RNA; a five carbon sugar.
RNA
Ribose Nucleic Acid; the nucleic acid that helps direct protein synthesis in the cytoplasm of a
cell.
Ribosomal RNA (rRNA)
Type of RNA found in ribosomes where protein synthesis occurs.
RNA transcription
The molecular reproduction process in cells which occur when a messenger RNA molecule is
made from a portion of a DNA molecule; the process occurs as one of the steps leading to
protein synthesis.
telophase
the last phase of mitosis during which cytokinesis of the cytoplasm occurs resulting in two new
daughter cells.
thymine (T)
one of the five nitrogen bases found only in the nucleotides composing the structure of DNA;
pairs with adenine.
transfer RNA (tRNA)
a type of RNA that carries a particular amino acid to a ribosome during protein synthesis; at one
end it binds to an amino acid and at the other end it has an anticodon that binds to an mRNA
codon.
translation
occurs when the sequence of bases of a mRNA directs the sequence of amino acids to produce a
specific protein at a ribosomal RNA site in the cytoplasm.
triplett code
during the process of protein synthesis this sequence of three nucleotide bases stands for a
particular amino acid; the sequence of nucleotide bases found on the DNA molecule; sometime
referred to as the Genetic code.
uracil (U)
One of the five nitrogen bases in the nucleotides composing the structure of RNA; pairs with
adenine.