chapter 1 Flashcards
what is development?
process of change where a multicellular organism arises from a single cell
what is a zygote?
when a sperm cell and an egg fuse together
when does a zygote turn into an embryo?
when fertilization begins; when the cells start to divide
what is gastrulation?
the movement of cells in regards to one another
what are the layers of the gastrula?
ectoderm, mesoderm and endoderm
what is a germ cell?
a cell during embryo development that will turn into a sperm or egg
what is organogenesis?
cell to cell signaling occurs and cells starts forming systems
what is metamorphosis of the frog?
loses tail and gains legs, loses teeth to be able to become a carnivore and the gills regress due to the frog being terrestial.
what did william harvey say about amniotic fluid?
described it as shock absorbing fluid for the embryo
what did von haller and bonnet say?
species remain constant, tissues could unravel at different rates so the embryo does not appear like an adult
who created the cell theory?
schleiden and schwann
who discovered the three germ layers?
christian pander- tripoblastic embryos have an ectoderm, mesoderm and an endoderm
what did karl ernst von baer discover?
the notochord and the mammalian egg
what are blastomeres?
cells in the cleavage stage
what is a vegetal pole?
hemisphere that is yolk rich
what is an animal pole?
hemisphere with lower yolk concentration
what is holoblastic cleavage
complete cleavage; isolecithal (equal) and mesolecithal (moderate)
what is meroblastic cleavage?
incomplete; telolecithal and centrolecithal- dense yolk that takes up more of the cell volume
what are the two major cell types?
epithelial and mesenchymal
What is invagination?
I folding of a sheet of cells much like a stress ball being poked
What is involution?
Inward movement of the outer layer so if spreads over the internal cells
What is ingression?
Migration of individual cells into interior, cells become mesenchymal ( separated) and migrate independently
what is delamination?
splitting cellular sheet into two more or less parallel sheets- similar to ingression bur forms a new sheet
what is epiboly?
movement of sheets spreading as a unit to enclose deeper layers of the embryo- can occur by cell division/shape change
what are the major body axes?
anterior-posterior, dorsal and ventral, left and right
what are the two microscoping approaches to studying vertebrate development?
fluorescence microscopy and scanning electron micrography
where is the notochord usually placed?
180 degrees from when sperm enters
what is direct observation?
seeing a certain pigmentation of a cell evolve in to other things for example trunk muscles- not applicable to most observations
what is dye marking?
narural dyes are placed on the embryo and as it grows and goes through gastrulation the dye spreads and it is noticeable what parts of the embryo turn into what
genetic labelling
tissue from the same spot in an embryo of two similar animals (quail and chick) are switched, specific proteins in the different spot can be tagged and followed through what they turn into
what is transgenic chimera?
similar to genetic labelling but from the same animal, embryo is dyed green so it is the same as animal being observed but green (GFP)
at what stage is an embryo more prone to teratogens?
from 3-8 weeks, women find out they’re pregnant at around 6 weeks
