A Glossary of Terms from Lab 5:
antheridium
The male sex organ or gametangium, within which male gametes are formed, in
algae, fungi, bryophytes (mosses, liverworts, etc.), and pteridophytes (ferns).
anther
the terminal pollen sac of a stamen, inside which pollen grains with
Male gametes form in the flower of an angiosperm.
asexual reproduction
A type of reproduction involving only one parent that produces genetically
identical offspring by budding or by the division of a single cell or the
entire organism into two or more parts.
binary
fission
The type of cell divisions by which prokaryotes reproduce; each dividing
daughter cell receives a copy of the single parental chromosome.
centriole
One of two structures in the center of animal cells, composed of cylinders of
nine triplet microtubules in a ring. Centrioles help organize microtubule
assembly during cell division
centromere
The centralized region joining two sister chromatids.
chromatid
One of a pair of duplicated chromosomes produced during the S phase of the cell
cycle, which are joined together at the centromere.
crossing over
The reciprocal exchange of genetic material between non-sister chromatids
during synapsis of meiosis I.
cytokinesis
The division of the cytoplasm to form two separate daughter cells
immediately after mitosis.
diploid
Refers to a cell nucleus containing two of each type of chromosome. Refers to
an organism in the main life stage having cell nuclei having two of each type
of chromosome, written as 2N.
gametes
Haploid egg or sperm cells that unite during sexual reproduction to produce
a diploid zygote.
gametogenesis
The process where haploid gametes are produced from diploid cells via meiosis.
In animals the two processes are spermatogenesis and oogenesis.
gametophyte
The part of the life cycle of plants having haploid nuclei and giving rise to
the sex cells that on fusing produce a diploid stage, usually the sporophyte.
haploid
Referring to a cell nucleus it contains one of each type of chromosome.
Referring to an organism it is one in which the main life stage has cell nuclei
with one of each type of chromosome, written as n.
haploid gametophyte
The part of the life cycle of plants having haploid nuclei and giving rise to
the sex cells that on fusing produce a diploid stage, usually the
sporophyte.
homologous
chromosomes
Chromosome pairs of the same length centromere position, and staining
pattern that possess genes for the same traits at corresponding loci. One
homologous chromosome is inherited from the organism's father, the other
from the mother.
homology
Similarity in characteristics resulting from a shared ancestry.
homospory
The possession of only one form of spore. This gives rise to a single gametophyte
generation carrying both male and female reproductive organs.
interphase
A
stage of growth in the cell cycle in which metabolism occurs without visible
evidence of nuclear division. Interphase is the phase between divisions (meiosis
and mitosis).
karyokinesis
The division of the cell nucleus.
meiosis
A type of nuclear division associated with sexual reproduction, producing
four haploid cells from a single diploid cell, the process involving two cycles
of division.
metaphase
A stage of nuclear division in eukaryote cells, occurring once in mitosis and
twice in meiosis. This phase begins when all of the centromeres line up at the
equatorial plane.
micropyle
A small canal in the integument surrounding the ovule of a flowering plant,
through which the pollen tube usually enters the ovule on the way to the embryo sac. Water enters the seed via the micropyle prior to
germination.
microsporangium
The sporangium from which the microspores are formed, which in higher
plants is the pollen sac.
microspore
The smaller of the two types of spore produced by ferns and higher plants,
giving rise to the male gametophyte. In Tracheophytes the microspore is the
pollen grain.
microsporocytes
Thousands of cells (pollen mother cells) found within a young
microsporangium.
mitosis
A process of cell division in eukaryotic cells conventionally divided into the
growth period (interphase) and four stages: prophase, metaphase, anaphase,
and telophase. The stages conserve chromosome number by equally
allocating replicated chromosomes to each of the daughter cells.
ovary
(1) in flowers, the portion of a carpel in which the egg-containing ovules
develop. (2) in animals, the structure that produces female gametes and
reproductive hormones.
oviduct
A tube passing from the ovary to the vagina in invertebrates or to the uterus
in vertebrates.
sexual reproduction
A type of reproduction in which two parents give rise to offspring that have
unique combinations of genes inherited from the gametes of the two
parents.
somatic cell
Any of the cells of a plant or animal except the reproductive cells.
sperm
Spermatozoon; a small, usually motile male gamete.
spore
In the life cycle of a plant or alga undergoing alternation of generations, a
meiotically produced haploid cell that divides mitotically, generating a
multicellular individual, the gametophyte, without fusing with another
cell.
sporophyte
The multicellular diploid form in organisms undergoing alternation of
generations that results from a union of gametes and that meiotically
produces haploid spores that grow into the gametophyte generation.
synapse
The locus where one neuron communicates with another neuron in a neural
pathway; a narrow gap between a synaptic terminal of an axon and a
signal-receiving portion (dendrite or cell body) of another neuron or effector
cell. Neurotransmitters released by synaptic terminals diffuse across the
synapse, relaying messages to the dendrite or effector.
tetrad
The four homologous chromatids that associate during prophase and
metaphase of meiosis and are involved in crossing over. A tetrad is also the
four haploid cells produced by one complete meiotic division.
uterus
The enlarged posterior portion of the oviduct in which the embryo implants a
develops in viviparous species. It is also called the womb of female
humans.
zygote
The diploid product of the union of haploid gametes in conception; a fertilized
egg.