Download Allele: An allele is one of two or more forms of the DNA sequence of

Allele: An allele is one of two or more forms of the DNA
sequence of a particular gene.
Anaphase:
Anaphase
is
of mitosis when chromosomes
opposite ends of the spindle.
the
move
stage
towards
Archeae:
The Archaeaare
a
group
of
singlecelled microorganisms.
A
single
individual
or species from this domain is called anarchaeon.
They
have
no cell
nucleus or
any
other organelles within their cells.
Binary fission: Binary fission, or prokaryotic fission, is the
form of asexual reproduction and cell division used
by all prokaryotes, some protozoa, and some
organelles
within eukaryotic organisms
which
results in the reproduction of a cell by division into
two parts each having the potential to grow to the
size of the original cell.
Bivalent: describing an associated pair of homologous
chromosomes as seen in meiosis.
Cell plate: The structure that forms at the equator of the
spindle during early telophase in the dividing cells
of plants and a few green algae.
Cell wall: The rigid, outermost layer of the cells of plants,
some protists, and most bacteria, surrounding
the cell (Plasma) membrane.
Cell: The cell is the functional basic unit of life.
Centromere: the primary constriction region of the
chromosome where the spindle fibres attach to
induce movement of chromosomes to the poles
during anaphase.
Chiasmata: An X-shaped figure that can be seen in the
light-microscope during meiosis; evidence of
crossing-over, where two chromatids have
exchanged parts. Chiasmata move to the ends of
the chromosome arms as the homologues
separate.
Chromatid: one half of a newly replicated chromosome
generally joined to its counterpart at the
centromere region.
Chromatin: The deoxyribonucleoprotein material of the
nucleus making up the chromosomes.
Chromosome: The gene-containing structure in cells
made up of DNA (in prokaryotic cells) and DNA
plus protein (in eukaryotic cells).
Crossing-over: The exchange of corresponding chromatid
segments between homologous chromosomes in
meiosis responsible for genetic recombination
between homologous chromosomes.
Cytokinesis: (Gr. kytos, hollow vessel+ kinesis,
movement). Division of the cytoplasm of a cell
after nuclear division.
Diploid: A cell having two sets
chromosomes in the nucleus.
of
homologous
Eukaryote: (Gr. eu, good+ karyon, kernel). A cell
characterized by membrane- bounded organelles,
mostly notably the nucleus, and one that
possesses chromosomes where DNA is associated
with proteins; an organism composed of such
cells.
Fertilization: The fusion of the two haploid gamete nuclei
to form a diploid zygote nucleus.
Gamete: A gamete is a haploid reproductive cell.
Gene: A gene is a unit of heredity in a living organism. It
is normally a stretch of DNA that codes for a type
of protein or for an RNA chain that has a function in
the organism.
Genetic
recombination:Genetic
recombination is
a
process by which a molecule of nucleic
acid (usually DNA, but can also be RNA) is broken
and then joined to a different DNA molecule.
Genome: The genome is the entirety of an organism's
hereditary information. It includes both the genes
and the non-coding sequences of the DNA.
Haploid: Describing
chromosomes.
a
cell having
a
single
set
of
Homologous chromosomes:Homologous chromosomes
are chromosome pairs of the same length,
centromere position, and staining pattern with
genes for the same characteristics at corresponding
loci.
Interphase: The period between two mitotic or meiotic
divisions in which a cell grows and its DNA
replicates; includes G1, S and G2 phases.
Kinetochore: The kinetochore is the protein structure on
chromosomes where the spindle fibers attach
during cell division to pull the chromosomes
apart.
Meiosis: Meiosis is a process of reductional division in
which the number of chromosomes per cell is cut
in half.
Metaphase: The stage of nuclear division during which
chromosomes are highly coiled and compacted and
are aligned along the equatorial plane of the
mitotic spindle before moving to opposite poles in
the cell.
Microtubule: (Gr. Mikros, small+Tubule, little pipe). In
eukaryotic cells, a long, hollow protein cylinder,
composed of the protein tubulin. These influence
cell shape, move the chromosomes in cell
division, and provide the functional
structure of cilia and flagella.
internal
Nucleus: The chromosome-containing compartment of
the eukaryotic cell, bounded by a double
membrane system.
Parthenogenesis: (Gr. Parthenos, virgin+ genesis, birth).
The development of an egg without fertilization, as
in aphids, bees, ants and some lizards.
Polyploidy: Condition in which one or more entire sets of
chromosomes is added to the diploid genome.
Prophase: The first stage of nuclear division during which
chromosomes thicken and become visible by light
microscopy.
Spindle apparatus: The assembly that carries out the
separation of chromosomes during cell division,
composed of microtubules (spindle fibres) and
assembled during prophase at the equator of the
dividing cell.
Synapsis: (Gr., Contact, union). The point-by-point
alignment (pairing) of homologous chromosomes
that occurs before the first meiotic division;
crossing-over takes place during synapsis.
Synaptonemal-complex: A protein lattice that forms
between
two
homologous
chromosomes
in
Prophase-I of meiosis, holding the replicated
chromosomes in precise register with each other so
that base pairs can form between non-sister
chromatids for crossing-over that is usually exact
within a gene sequence.
Zygote: (Gr. Zygotes, paired together). The diploid (2n)
cell resulting from the fusion of male and female
gametes (fertilization).