Development Flashcards
What is developmental biology? (4)
- the study of how a fertilised egg becomes an adult organism
- how an adult organism reproduces
- how an organism ages and dies
- how an organism repairs and replaces cells and tissues after damage/under normal conditions
why does the study of development matter?
- better understanding of congenital birth defects
- leads to new and more effective treatments for human diseases (regenerative medicine)
- evolutionary development (better understanding of evolution)
what has allowed us to study developmental biology?
model organisms
what are the 2 types of model organisms?
- protosomes
- deuterostomes
what does proto mean?
first (greek)
what does deutero mean?
second (greek)
what does stoma mean?
mouth (greek)
what’s a protostome?
organism in which the mouth forms first
what’s a deuterostome?
organism in which the mouth forms second
by which name is arabidosis thaliana better known?
thale cress
give 3 benefits of the use of arabidosis thaliana
small easy to grow short generation time (genetics) embryology good imaging sequenced genome transgenic plants can be made using agrobacterium
by what name is dictyostelium discoideum better known?
slime mould
is slime mould a proto or deuterostome?
proto
give 3 benefits of the use of dictyostelium discoideum
multicellular chemotaxis genetics sequenced genome transgenesis social behaviour (altruism) looks/behaves similarly to phagocytes
are hydra proto or deueterostomes?
proto
what are 3 benefits of the use of hydra?
- radial symmetry
- diploblastic (double bud- endo and ectoderm)
- small
easy to grow
sexual and asexual reproduction
high regenerative capacity
what are Planaria better known as?
flatworm
are flatworms proto or deuterostomes?
proto
give 3 benefits to using flatworms
adult stem cells- regenerative capacity
sexual and asexual reproduction
triploblastic- endo, ecto and mesoderm
by what name are caenorhabditis elegans better known?
round worm
are round worms proto or deuterostomes?
proto
give 3 benefits of using round worms
- have few cells short generation time 2 sexes genetics and transgenics study of ageing- short lifespan RNA knockout technology sequenced genome lineage of cells known imaging
by what name are drosophila melanogaster better known?
fruit flies
are fruit flies proto or deuterostomes?
proto
give 3 benefits of using fruit flies
short generation time genetics transgenesis sequenced genome imagery segmental athropod
by what name are parhyale hawaiensis better known?
amphipod crustacean
are amphipod crustaceans proto or deuterosomes?
proto
give 3 benefits of using amphipod crustaceans
- athropods short generation time genetics sequenced gemone high regenerative capacity transgenesis transparent
by what name are stronglyocentrotus purpuratus better known?
sea urchins
are sea urchins proto or deuterostomes?
deutero
give 3 benefits of using sea urchins
-imaging produces many eggs transparent embryos injection of nucleic acids basal deuterostome
by what name are ciona intestinalis better known?
sea vase
are sea vases proto or deuterostomes?
deutero
give 3 benefits of the use of sea vases
transgenesis genetics sequenced genome imaging basal chordate spinal cord inverterbrae
are brachiostoma lanceolatum proto or deuterostomes?
deutero
give 3 benefits of using brachiostoma lanceolatum
sequenced genome
invertebrate
basal chordate
by what name are danio rerio better known?
zebrafish
are zebrafish proto or deuterostomes?
deutero
give 3 benefits of zebrafish
genetics sequenced genome transgenesis imaging regulation capacity external development vertebrate
are frog embryos proto or deuterostomes?
deuterostomes
give 3 benefits of using frog embryos
embryology generated in large numbers transparent tadpoles easy to make explants and perform transplantations transgenic pancreas present regeneration
what are gallus gallus?
chicks
are chicks proto or deuterostomes?
deuterostomes
give 3 benefits of using chicks
transplantation experiments
sequenced genome
overexpression and knock out experiments
by what name is Mus musculus better known?
mouse
are mice proto or deuterostomes?
deutero
give 2 benefits of using mice
strong genes
mammal
give 3 benefits of using homo sapiens
genetics
mammal
sequenced genome induced pluripotent embryonic stem cells
how many thoracic segments in adult fruit flies?
3
where are the notum and wings found on a fly?
the 2nd thoracic segment
where are the halters found on a fly?
the 3rd thoracic segment
what happens when there’s a mutation in the bithorax complex?
the 3rd thoracic segment can be transfotmed into the 2nd thoracic segment, therefore there are 2 2nd thoracic segments
what are homeotic mutations?
where one body part has been transformed into another
where are genes for mutant and non-mutant parts of the fruit fly found?
in the same region of the chromosome
in what were hox genes first identified?
in drosophila
what did hox genes cause in drosophila?
homeotic mutations/transformations
hox genes are evolutionarily conserved, what does this mean?
they’ve remained essentially unchanged throughout evolution
what’s the homeodomain?
the region on a protein that binds to the DNA
where are hox genes found?
clustered in the genome
what’s tandem gene duplication?
where unequal crossover is caused by a chromosome mispairing at meiosis, possibly due to repeated DNA sequences
what are paralogous genes?
duplicated genes within a single genome
what are orthologous genes?
the same gene in different organisms
what are homologous genes?
genes that share a single common ancestor
what does it mean when genes are duplicated in tandem?
each is the same as the last
if each gene is the same as the last, what is there?
redundancy
if there’s redundancy in the genes is it ok if one is lost? why?
yes as there’s no selection pressure for the genes to be there
what do the genes in tandem acquire new functions over time?
new functions
is it ok if one of the genes with a new acquired function is lost?
no as the genes are different so there isn’t simply the same gene to replace it
what is subfunctionalization?
a neutral mutation process where no new adaptations are made
what are the 2 mechanisms of subfunctionalization?
change in protein sequence
change in time/place of gene expression
what’s segmental duplication?
a big tandem duplication affecting a whole chunk of chromosome
what can tandem and segmental duplication events give rise to in drosophila?
2 hox clusters
by what 2 mechanisms can whole genome duplication events occur by?
- allotetraploidy
- autotetraploidy
what’s allotetraploidy?
hybridization between 2 separate species
what’s autotetraploidy?
duplication of genome through improper meiosis- instead of haploid germ cells, there are diploid germ cells giving tetraploid organisms
diplo meaning
2
triplo meaning
3
zoa meaning
life
blast meaning
bud
derm meaning
skin
noto meaning
back
endo meaning
inside
meso meaning
middle
ecto meaning
outside
meta meaning
after
chord meaning
string/rope
uro meaning
tail
cephalo meaning
head
echino meaning
spiny/prickly
protozoan meaning
first/primitive life
metazoan meaning
multicellular animals
diploblastic meaning
containing 2 tissue layers
triploblastic meaning
containing 3 tissue layers
endoderm meaning
tissue (germ layer) on the inside
what does the endoderm give rise to?
internal organs
mesoderm meaning
tissue (germ layer) in the middle
what does the mesoderm give rise to?
notochord, muscle etc
ectoderm meaning
tissue (germ layer) on the outside
what does the ectoderm give rise to?
skin and nervous system
chordate meaning
animal without notochords
notochord meaning
chord in the back
urochordate meaning
animal with notochord in their tails
cephalochordate meaning
animals with notochord extending to their heads
echinoderm meaning
prickly skin
give an example of an echinoderm
sea urchin
what is descriptive embryology?
- experiments which aim to define normal embryonic development with minimal disruption of the process
- leads to an understanding of what happens during development- but not how
what is experimental embryology?
- experiments which aim to define how embryonic development occurs e.g. how and when cells acquire their fate
- requires experiments that perturb normal development- manipulations
e. g. transplantation studies to find whether the cell or its surroundings controls outcome
what’s morphogenesis?
process by which form is generated- involves coordinated cell movement
what’s gastrulation?
morphogenic process by which the ectoderm, mesoderm and endoderm layers reach their final position in embryo
morpho meaning?
shape/form
genesis meaning?
birth/origin
what’s neurulation
morphogenic process by which the nervous system begins to form- especially formation of neural tube
what’s a blastomere?
a cell in the early embryo
what’s a fate map?
- assessment of the fate of a cell/group of cells based on lineage labelling
- answers question- what will this cell become if left to develop undisturbed in embryo ?
what part of embryology is a fate map part of?
descriptive
what’s a specification map?
- assessment of what a cell or group of cells will form into if removed from their embryonic environment (neighbouring cells)
- asking what a cell ‘thinks’ it should become when isolated from neighbours
what part of embryology is a specification map part of?
experimental
what is meant by determined?
cell/tissue is determined if it will still develop according to its fate, even when transplanted into another site in the embryo (a new environment)
what is meant by competence?
the range of cell fates which can be achieved by a cell/group of cells given the appropriate conditions (what it is capable of becoming)
what’s induction?
the process by which a cell/group of cells emits signals to its neighbouring cells, thereby changing their fate
what was done in the organizer experiment 1924?
took dorsal mesoderm from newt embryo and put into the ventral side of the other embryo –> gave siamese twin embryo
what’s homeotic mutation?
mutation which results in the transformation of one body structure into another
what is a hox gene?
a family of genes which encode related transcription factors characterised by containing a DNA binding domain- the homeodomain/homeobox
evolutionary conserved
where were hox genes first identified?
drosophila
what did the hox genes show in the drosophila?
they are involved in anterior posterior patterning
what can mutations in hox genes lead to?
homeotic mutation
where are hox genes found?
clustered in the genome
what’s colinearity?
genes in the 3’ end are expressed progressively earllier and more anteriorly that genes in the 5’ end of the cluster
what are the 3 sources of evidence for the effects of hox genes?
- expression pattern
- comparative embryology
- gene knockout experiments
what are somites?
mesoderm derivative
segmental blocks of tissue forming from anterior to posterior
what do somites give rise to?
muscles, vertebrae and dermis of the skin
what are homologous genes?
genes that share a common ancestral gene
what are paralogous genes?
duplicated genes within a single genome
what are orthologous genes?
same gene, different organism
what is gene redundancy?
situation where no phenotype is observed when a gene is mutated because another gene can replace/substitute the function of the mutated gene
masks the role of a mutated gene
what do phenotypes arising from mutation show?
what the gene is required for
what are the 3 modes of gene duplication?
tandem
segmental
whole genome
what causes tandem gene duplication?
chromosomes mis-pairing at meiosis, possibly caused by repeat DNA sequences
what’s segmental gene duplication?
giant tandem duplication (whole chunk of chromosome)
what are the 2 whole genome duplication events called?
allotetraploidy
autotetraploidy
what’s potency?
the range of cell fates available to a cell or a group of cells (similar to competence)
what’s totipotent?
cells that can give rise to all cells in the embryo- even extra embryonic membranes+ tissues
what’s pluripotent?
cells that can give rise to most, but not all cells in the embryo
what’s bipotent?
cells that can give rise to 2 cell types
what’s unipotent?
cells that can give rise to 1 cell type
what did mangold and speman do?
discovered the organiser
what did speman do?
discovered nucleus at 16 cell stage was totipotent
what did briggs and kings do?
first to successfully transplant nuclei into eggs
what did gordon do?
first to clone an adult animal through nuclear transplantation
what did cambell and wilimit do?
first to clone a mammal (dolly)
what did martin evans do?
first to isolate and culture embryonic stem cells from mouse embryos
what did shinya yamanka do?
first to successfully indice pluripotency without the need to transplant nuclei into eggs or generate embryos
what does the waddington landscape show?
potency decreases over time
what doesn’t the waddington landscape show?
it’s not one way, cells can be driven back up to become more potent
what are the three parts of the mammalian preimplantation blastocyst embryo?
epiblast
trophoblast
blastocode
what’s the epiplast/inner cell mass?
gives rise to the embryo including the germ cells- source of pluripotent embryonic stem cells
what’s the trophoblast?
gives rise to extraembryonic membranes including the placenta
what makes Human Embryonic Stem (hES) and induced Pluripotent Stem (iPS) cells valuable? (4)
- study human embryonic development in vitro
- generate organs in vitro
- model genetic diseases in vitro
- harness to treat genetic diseases in humans
what do adult stem cells do?
play a role in replacing cells throughout life
where are adult stem cells found- give 3
3 from bone marrow skin hair follicle gut blood
what are stem cells sensitive to?
radiation and chemotherapy
what was the first successful example of stem cell therapy in humans?
bone marrow transplantation
what stem cells are found in bone marrow?
human hematopoietic
what can limbic SCs treat?
corneal injuries
what can keratinocyte SCs treat?
burn injuries
what’s the beauty of using human derived induced pluripotent stem cells?
the patient themselves provides the cells- no issues in rejection (personalised medicine)
