Development Flashcards
what is development?
the study of the development of organisms
Arabidopsis
thale cress
dictyostelium
slime mould
hydra
cnidarian
planarians
flatworms
caenorhabditis
nematode worm
drosophila
fruit fly
parhyale
amphipod crustacean
strongylocentrotus
sea urchin
ciona
tunica / sea squirt
brachiostoma
amphioxus
danio
zebrafish
xenopus
clawed frog
gallus
chick
mus
mouse
homo
human
what is the difference between a protostome and a deutosterome
proto - mouth forms first
deuto - mouth forms second
what is the difference between a protozoan and a metozoan organism?
proto = first or primitive life
meta = multicellular modern animals
what is the difference between a diploblastic and a triploblastic organism?
diplo = 2 tissue layers
triplo = 3 tissue layers
what do the terms endoderm, mesoderm, and ectoderm refer to?
endo - inner tissue layer - internal organs
meso - middle tissue layer - notochord, muscle, kidney, blood
ecto - outer tissue layer - skin, nervous systems
what is the notochord?
the first tissue to differentiate in chordates
‘chord in the back’
what is a chordate?
an animal with a chordate
what is the difference between a urochordate and a cephalochordate?
uro - animals with notochords in tail
cephalo - animals with notochords extending into head
what is an echinoderm?
prickly skin
- group of animals e.g. sea urchins
how do cells acquire their fate?
- inheritance of cell fate determinants
- asymmetric inheritance of cytoplasmic determinants
what is descriptive embryology?
- aiming to define normal embryonic development with minimal disruption to the process
- shows what happens, not how it happens
what is experimental embryology?
- aiming to define how embryonic development occurs
- gains mechanistic insight into how cells gain their fate
- requires you to perturb normal developmental proceses
what is morphogenesis?
the process by which form is generated
what is gastrulation?
the morphogenetic process by which endoderm, mesoderm, and ectoderm layers reach their final positions in the embryo
what is neuralation?
the morphogenetic process by which the nervous system begins to form, e.g. neural tube formation
what is a blastomere?
a cell in the early embryo
what is a fate map?
the assessment of the fate of a cell or group of cells based on lineage labelling
- descriptive embryology
what is a specification map?
the assessment of what a cell or group of cells will form if removed from their embryonic environments
- experimental embryology
what does it mean for a cell or tissue to be ‘determined’?
a cell or tissue is determined if it will still develop according to its fate, even when transplanted into a different site in the embyro
what does it mean if the fate map is equivalent to the specification map?
- cells within embryo do not rely on cell-cell communication to achieve normal fate
- mosaic development - asymmetric inheritance of cytoplasmic determinants
what does it mean if the fate map is not equivalent to the specification map?
- cells receive instructions from its environment at a later point of development prior to assuming normal fate
- regulative development - cell-cell communication / induction
what is competence?
the range of cell fates, which can be achieved by a cell or group of cells given the appropriate conditions
- e.g. a cell may be competent to give rise to many cell types that it would not normally be specified to form
what is induction?
the process by which a cell emits signals to neighbouring cells to change their fate
what did the organizer experiment tell us?
- dorsal mesoderm is determined by early gastrula stage
- induction of muscle and neural tissue
- ventral ectoderm and mesoderm are competent to become neural and somatic tissue
what is the organizer?
- the dorsal mesoderm at the gastrula stage
- induces overlying ectoderm to become neural and induces neighbouring mesoderm to become muscle
what is the nieuwkoop centre?
the region of the early dorsal vegetal pole in blastula stage which induces the organiser (activates Wnt signalling)
what is a homeotic mutation?
a mutation that results in the transformation of one body part into another
what are hox genes?
a family of genes that contains homeodomain - evolutionarily conserved
what are the 3 ways in which genes can duplicate?
- tandem gene duplication
- segmental duplication
- whole genome duplication events
either via autotetraploidy or allotetraploidy - auto = duplication of genome through improper meosis
- allo = hybridization between two separate species - followed by failure in meiosis
what are the 4 steps involved with the 2R hypothesis?
- an ancestral cluster undergoes a duplication event
- gene loss events occur to lose some genes
- 2nd round duplication event occurs
- second set of gene loss events occurs
what are the 3 pieces of evidence that hox gene expression gives positional identity along the anterio-posterios axis?
- expression pattern
- comparative embryology
- gene knockout experiments
what are homologous genes?
genes that share a common ancestral gene
what are paralogous genes?
duplicated genes within a single genome
- duplicates known as paralogues
what are orthologous genes?
the same gene present in different organisms
what is gene redundancy?
a situation where no phenotype change is observed when a gene is mutated because another gene (usually a paralogue) can replace the mutated gene
what is potency?
the range of cell fates available to a cell or group of cells
(potency + competence have similar meanings)
what are the different levels of cell potency?
- totipotent - cell can give rise to all embryonic cells, including extraembryonic cells + tissues
- pluripotent - cell can give rise to most, but not all cells of embryo
- bipotent - cell can give rise to only 2 cell types
- unipotent - cell can give rise to only 1 cell type
what does the waddington landscape represent?
the idea that cell potency decreases with time - i.e. starts out totipotent, and decreases over time to become unipotent
- halting development can maintain cells in a pluripotent state long term in culture
- nuclear reprogramming studies - reprogramming differentiated cells back to an embryonic pluripotent state
why are hES and iPS cells valuable?
- used to study human embryonic development in vitro
- used to generate organs in vitro
- used to model genetic diseases in vitro
- harnessed to treat genetic diseases in humans
