lec set 1 Flashcards
What is development of an organism?
how that organism:
- maintains tissue homeostasis
- adapts to its environment
- produces other single cells that then aid in the reproduction of the species
- evolves as a species
Definition: gamete
a specialized reproductive cell through which sexually reproducing parents pass chromosomes to their offspring (a sperm or an egg)
Definition: zygote
a fertilized egg with a diploid chromosomal complement in its zygote nucleus generated by fusion of the haploid male and female pronuclei
Definition: clevage
a series of rapid biotic cell divisions following fertilization in many early embryos
- it divides the embryo without increasing its mass
Definition: blastomere
a cleavage-stage cell resulting from mitosis
Definition: morula
vertebrate embryo of 16-64 cells
- proceeds the blastula/ blastocyst stage
Definition: blastula
early stage embryo consisting of a sphere of cells surrounding an inner fluid-filled cavity (the blastocoel)
Definition: blastocoel
inner fluid filled cavity of blastula
Definition: gastrulation
a process involving movement of the blasters of the embryo relative to one another resulting in the formation of three germ layers of the embryo
Definition: gastrula
a stage of the embryo following gastrulation that contains the three germs layers that will interact to GENERATE THE ORGANS OF THE BODY
Definition: 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 (expect for the germ cells)
Definition: triploblastic
having three germ layers (most animals have this)
Definition: diploblastic
having two germ layers (lacking a mesoderm) (jellyfish, corals or sea anemones)
Definition: ectoderm
- greek = outside
- the cells that remain on either the outside or dorsal surface of the embryo following gastrulation
- the layer that forms the nervous system and the epidermis
Definition: mesoderm
- greek = between
- the middle of the three germ layers
- gives rise to:
- muscles and skeleton,
- connective tissue
- the reproductive organs
- the kidney
- blood and most of cardiovascular tissue
Definition: endoderm
- greek = within
- the inner most germ layer
- forms the:
- epithelial lining of the respiratory tracts
- the gastrointestinal tract
- accessory organs of digestive tract (eg. liver, pancreas)
Definition: organogenesis
interactions between and rearrangement of cells of the three germ layers to produce tissue and organs
Definition: germ cells
cells for reproductive function
Definition: somatic cells
- greek soma = body
- cells that form the body
- all cells that are not germ cells
what is holoblastic cleavage?
- greek holos = complete
- a cell division (cleavage) pattern in the embryo in which the entire egg is divided into smaller cells
- frogs and mammals
what is mesoblastic cleavage?
- greek meros = part
- the cell division (cleavage) pattern in zygotes containing large amounts of yolk where only a portion of the cytoplasm is cleaved.
what are the beliefs of epigenesis theory of embryology?
organs of the embryo were formed from scratch or de novo each generation
what are the beliefs of preformation theory of embryology?
organisms were already present in miniature form
- the theory concept of homunculus formed from this theory
- fully-formed human, or “homunculus,” existed within either the sperm or the egg and would simply enlarge over time
what is the recapitulation theory?
the idea that ontogeny (growth and development) occurs through a variety of stages that are representative of the evolutionary phylogeny of a particular species
- it “replicates” the evolutionary history of a species
