Module 1 - BIOL 303 Flashcards
syndactyly
failure of programmed cell death in the development of digits
Development
The process of progressive and continuous change that generates a complex multicellular organism from a single cell.
Support for epigenisis
Kaspar Friedrich Wolff (1767)
chick embryonic parts develop from tissues that have no recognizable adult counterpart
heart and blood vessels seen to develop anew
intestinal tube formation observed as folding of what was originally a flat tissue
recapitulation
the idea that ontogeny (growth and development) occurs through a variety of stages that are representative of the evolutionary phylogeny of a particular species
Fertilization
Fusion of male and female gametes followed by fusion of the haploid gamete nuclei to restore the full complement of chromosomes characteristic of the species and initiation in the egg cytoplasm of those reactions that permit development to proceed.
Gamete
A specialized reproductive cell through which sexually reproducing parents pass chromosomes to their offspring; a sperm or an egg.
Genome
The complete DNA sequence of an individual organism.
Cleavage
A series of rapid mitotic cell divisions following fertilization in many early embryos; cleavage divides the embryo without increasing its mass.
Blastomere
A cleavage-stage cell resulting from mitosis.
Morula
Latin, “mulberry.” Vertebrate embryo of 16–64 cells;, precedes the blastula or blastocyst stage.
Blastula
Early-stage embryo consisting of a sphere of cells surrounding an inner fluid-filled cavity, the blastocoel. Sometimes this single layer stage before and during gastrulation is known as the blastoderm.
Gastrulation
A process involving movement of the blastomeres of the embryo relative to one another resulting in the formation of the three germ layers of the embryo.
Gastrula
A stage of the embryo following gastrulation that contains the three germ layers that will interact to generate the organs of the body.
Zygote:
A fertilized egg with a diploid chromosomal complement in its zygote nucleus generated by fusion of the haploid male and female pronuclei.
Embryo:
A developing organism prior to birth or hatching. In mammals, the term embryo generally refers to the early stages of development, starting with the fertilized egg until the end of organogenesis (embryonic period). After this, the developing mammal is called a fetus until birth, at which time it becomes a neonate.
Embryology
The study of animal development from fertilization to hatching or birth.
Germ layer
One of the three layers of the vertebrate embryo generated by the process of gastrulation, that will form all of the tissues of the body except for the germ cells
Ectoderm:
“outside.” The cells that remain on either the outside (amphibian) or dorsal (avian, mammalian) surface of the embryo following gastrulation. Of the 3 germ layers, the ectoderm is the one that forms the nervous system from the neural tube and neural crest and also generates the epidermis covering the embryo.
Endoderm:
Greek endon, “within.” The innermost germ layer; forms the epithelial lining of the respiratory tract, the gastrointestinal tract, and the accessory organs (e.g., liver, pancreas) of the digestive tract. In the amphibian embryo, the yolk-containing cells of the vegetal hemisphere become endoderm. In mammalian and avian embryos, the endoderm is the most ventral of the three germ layers, continuous with the yolk sack epithelium.
Mesoderm:
Greek mesos, “between.” The middle of the three embryonic germ layers, lying between the ectoderm and the endoderm. The mesoderm gives rise to muscles and skeleton; connective tissue; the reproductive organs; and to kidneys, blood, and most of the cardiovascular tissue
Organogenesis
Interactions between, and rearrangement of, cells of the three germ layers to produce tissues and organs.
Metamorphosis
Changing from one form to another, such as the transformation of an insect larva to a sexually mature adult - or a tadpole to a frog.
Germline cells
A group of cells set aside from the somatic cells (somatic cells form the rest of the embryo) for reproductive function. Consists of the cells of the gonads (ovary and testis) that undergo meiotic cell divisions to generate the gametes (egg and sperm).
Somatic cells
Greek soma, body. Cells that form the body; all cells in the organism that are not germline cells.
often first differenciation
The separation of the germline cells from somatic cells is often one of the first differentiations that occurs during animal development.
Epithelial Cells
form sheets connected by junctional complexes
sheets act as a barrier
move in harmony
have a clear polar character from one side to another
basal lamina is a foundation contacts only one surface of the cell
Mesenchymal Cells
loosely organized and loosely attached cells (more like bold individuals)
can migrate as individual cells
can also adhere in 3-dimensional clumps
basal lamina may surround the cells (muscle or fat cells)
Morphogenesis:
The organization of the cells of the body into functional structures via coordinated cellular processes such as:
cell movement or migration
cell growth
cell death
cell division
cell shape changes
changes in composition of cell membrane or secreted products.
cell growth
cell growth – some cells become smaller (sperm cells) or larger (egg cells)
cell death –
cell death – programmed removal of superfluous cells or entire tissues
cell division –
cell division – direction and amount of
cell shape changes
cell shape changes (can also involve change in character from epithelial to mesenchymal – also occurs as cancer cells spread or metastasize)
changes in composition of cell membrane or secreted products –
extracellular matrix can influence whether neighbouring cells migrate
Fate Map:
Fate Map:
A map of the developmental fate of a zygote or early embryo showing the adult organs that will develop from material at a given position on the zygote or early embryo.
Fate maps- direct observations
Some embryos have few cells and obvious differences in cytoplasmic pigmentation of early blastomeres.
fate map constructed? – vital dyes
A vital dye is a stain that can be used on living cells without killing them – the old fashion method.
fate map constructed? – fluorescent dyes
Fluorescent dyes are much better than vital dyes – sometimes injected and then photo-activated using a laser which allows a small group of cells to be “tagged” and their movements and lineage traced.
cell fate – chimeric embryos
Le Douarin found that quail cells could be grafted into chick embryos. The distinctive large nucleolus of quail cells served as a marker in tissues that were fixed, stained, and examined by standard light microscopy.
What is the function of the nucleolus?
Ribosome biogenesis
The nucleolus is the most prominent substructure within the nucleus.
It is the site of rRNA transcription and rRNA processing
a mammalian cell has 5-10 million ribosomes that are synthesized each time a cell divides
THE NUCLEOLUS IS A RIBOSOME PRODUCTION FACTORY it produces and assembles ribosomal subunits
Homologous structures
Homologous structures are similar because they are derived from a common ancestral structure – our arms and the bat’s wings are homologous structures (but they do not necessarily perform similar functions).
As forelimbs, the bird and bat are homologous, because they shared a common ancestor with the typical forelimb structure.
Analogous structures
Analogous structures are similar because they perform similar functions, but they do not necessarily share a common ancestral form – the bat’s wing and the butterfly’s wing are analogous structures (used in generating flight).
But as wings, the bird and bat wings evolved from the forelimb independently, and there was no common winged ancestor – thus as wings these are better considered as analogous.
another word for gene mutation
aneuploidy
Piebald syndrome
syndromes where a homologous gene in a model organism is mutated. (Mutation of the gene KIT in humans and mouse results in similar syndromes
Down’s syndrome
aneuploidy
Teratogen:
Teratogen: any agent that can disturb the proper development of an embryo or fetus (teratogens can result in birth defects or spontaneous abortion).
Developmental abnormalities are characterized as
“malformations
Developmental abnormalities if they are of a genetic nature
“disruptions” if they are associated with exposure to an exogenous agent such as a teratogen.
syndactyly : a malformation or a disruption?
syndactyly : malformation – interestingly all kangaroos have syndactyly – in which case it I would say it is now part of normal development
