Developmental Biology

  • Created by: Sarah
  • Created on: 11-04-17 07:51
what was the critisms of Gurdons first nuclear transfer in xenopus?
tadpole gut cell not fully differentiated- stem cell like turnover and low frequency of success (no adults)
1 of 371
what was Briggs and Kings experiment for nuclear potency?
used Rana(frog), needle to extract chrs out of egg cell, egg cell with no GM, replaced GM with nucleus from cell in blastula stage embryon--> normal tadpole, blastula nucleus pluripotent
2 of 371
what are the 2 hypotheses to explain why cells lose potency?
1) gene loss 2) differential gene activity
3 of 371
what experiments show that genes are not lost when cells differentiate, expression controlled by cytoplasmic factors and gene expression of differentiated can be changed?
lens regeneration in newt, human liver cell fuses with rat muscle cell expresses human muscle proteins, xenopus kidney cells in pleuroedeles oocyte produces xenopus oocyte proteins
4 of 371
what happens in lens regeneration in newts?
lens usually produced from placodes, when lens destroyed iris dorsal cells proliferagion, de-differentiation and re-differentiation, iris cells make crystallin proteins for lens
5 of 371
exceptions to gene loss rule?
1) gene arrangments in b lymphocytes 2) chromosome dimuntion fragmentation in unwanted chrms in parascaris except in germ plasm which become germ cells
6 of 371
what can now be done to show that muscle protein genes are in white blood cell DNA?
genomic sequencing
7 of 371
what marker did they use in dolly the sheep?
surrogate had black face, cell from the mammary epithelium were white
8 of 371
when were the cells best for the mammary epithelial cells?
in low serum, exit mitosis and enter gap 0 phase
9 of 371
how did they check the authenticity of dolly the sheep?
DNA fingerprinting (microsatellite analysis), DNA sequencing
10 of 371
what is dorsal?
transcription factor
11 of 371
what does dorsal activate?
mesoderm ventral side of embryo zygotic genes transcription (twist and snail)
12 of 371
what genes are on the ventral side of the embryo?
twist and snail
13 of 371
what are dorsalized class of mutant required for ventral fates?
STD, Spatzle, Toll and Dorsal
14 of 371
what is spatzle in the toll pathway?
the ligand
15 of 371
what is toll?
transmembrane receptor
16 of 371
on what side does dorsal enter the nuclei?
ventral side (where toll signalling is active)
17 of 371
why is the toll pathway only active on the ventral side?
spatzle ligand only present on the ventral side in the perivitelline space, reflects DV patterning, set up signalling between follicle and oocyte cells
18 of 371
how did they show myod is sufficent for muscle development?
transfect fibroblats (with no Myod) with Myod -> differentiates into muscle therefore sufficient
19 of 371
why is myod not absolutely required?
when no Myod muscle still develops because of redudancy another TF- Myf5
20 of 371
what is redudancy?
having several genes that perform the same role to some extent, if ones not present the other jumps in
21 of 371
what are stem cells?
undifferentated, they renew cells that are continually lost or repair tissue
22 of 371
what are stem cells in muscle?
satellite cells
23 of 371
where do satellite cells lie in muscles? what do they express?
between basal and cell membrane, expresses marker proteins pax7
24 of 371
how is the Myod expression maintained?
it maintains its own expression by positive feedback
25 of 371
what are cell-type specific proteins in muscle?
muscle specific actin, myosin 2, tropomyosin and enzymes (phosphate kinase)
26 of 371
what does ultrabithorax act as a selector gene for?
haltere identity, T3 metathoracic pathway
27 of 371
what is the ultrabithrax mutation what does it cause?
recessive mutation, causes transformation of T2 to T3
28 of 371
What is a homeotic mutation?
one structure is replaced by another, does not alter the number of segments
29 of 371
what is an example of non-autonomous function
signalling molecules (affects other cells)
30 of 371
what are the 2 hypotheses to restriction in potency?
1) differential gene activity 2) gene loss
31 of 371
what happened in the experiment with lens regeneration in the newt?
lens removed -> proliferation of cells in dorsal iris -> synthesis of crystallin proteins (found in lens) -> iris cells have genes for crystallin can make lens
32 of 371
what does the experiment with human liver cell transplated into s rat muscle cell (heterokaryon) tell us?
human liver gene off, human muscle gene on, cytoplasm induces change therefore genes not lost as can change cell types
33 of 371
what is holoprosencephaly caused by?
mutations of hh and loss of signalling
34 of 371
why does a steroid alkaloid casuse cyclopoedia?
blocks hh pathway and inhibits action of smo pathway
35 of 371
why do we need animal models of human disease?
development of diagnostic tools, dev of therapeutic (stem cells, pro structure for drug design)
36 of 371
where is shh signalling expressedin the limb bud?
in the limb bud, at the midline (notochord+floorplate)
37 of 371
what is the transcription factor in the shh pathway?
38 of 371
what is the TF in the hh pathway (invertebrates)?
39 of 371
what happens in prexial polydactylyl?
extra digits
40 of 371
what is preaxial polydactylyl caused by?
overactivity of hh signalling (mutation in a shh enhancer region)
41 of 371
what can result with problems in shh signalling?
preaxial polydactylyl, holoprosencephaly, basal cell carcinoma (cancer)
42 of 371
what happens in holoprosencephaly?
cyclopia-eyes fuse together, range of midline malformations (undivided midbrain)
43 of 371
what is holoprosencephaly caused by?
loss of function of hh signalling (dominat mutations in the shh gene)
44 of 371
example of gain of function hh signalling?
preaxial polydactyl
45 of 371
example of gain of function hh signalling (dominant mutation in shh)
46 of 371
what is cyclopamine?
steroidal alkaloid
47 of 371
where is cyclopamine from?
californian corn lily- plant
48 of 371
what is an example of a compound that disrupts shh signalling?
49 of 371
what is a teratogenic effect?
compound that disrupts shh signalling
50 of 371
what does cyclopamine cause in the early embryo?
cyclopia, mimics genetic loss of shh function
51 of 371
how does cyclopamine prevent shh signalling?
cyclopamine binds to the smoothened protein
52 of 371
why do developmntal signalling pathways (like hh) need to be kept ast a low level in adults?
inappropriate activaton can cause cancer, act like stem cells, cells divide
53 of 371
what is basal cell carcinoma caused by?
1) too much sun 2) hereditary-disruption in genes in hh pathway
54 of 371
an amorphic loss of function of what gene causes basal cell carcinoma
55 of 371
a gain of function (hypermorphic) mutation in what causes cancer?
56 of 371
what happens in the hereditary form of basal cell carcinoma?
stem cells in stratum basale layer inappropriately inactivated
57 of 371
what does inappropriate activation of the wnt pathway cause?
APC mutation and colon cancer
58 of 371
how are cancer cells like embryonic cells?
rapidly dividing, undifferentiated, epithelial to mesechymal transition (metastasis)
59 of 371
how are tumour cells different from embryonic cells?
escape normal controls on: proliferation, growth and differentiation
60 of 371
why do most cancers occur in epithelia?
they contain many stem cells that continue to proliferate and fail to differentiate
61 of 371
what is SMO?
62 of 371
what kind of mutation does SMO cause that causes cancer?
gain of function (hypermorphic)
63 of 371
what are tumour supressor genes in cancer? hh example?
loss of function genes eg PTC (amorphic, hypomorphic and antimorphic)
64 of 371
what is an antimorphic mutation?
a dominant negative mutation, mutant copy produces a product that inteferes with WT function
65 of 371
what is a nonsense mutation?
changes amino acid to stop codon
66 of 371
what is an amorphic/null mutation?
one that gives complete loss of gene function
67 of 371
how would you treat a cancer caused by overactivation of Hh signalling?
treat with GDC-449 (similar to cylopamine)
68 of 371
what is the problem with treating cancer with drugs like GDC-449 which disturb the Hh pathway?
treatment is short lived
69 of 371
what is the name used to decribe development where cells are determined late/not early in dev?
70 of 371
what is mosaci development?
cells are determined early in development
71 of 371
what are the features of mosaic development?
autonomous fashion, isolated cells develop as normal, a defect in part of embryo doesnt affect the other part
72 of 371
what experiment was used to show mosaic development?
roux, inserted a hot needle into 1 cells of 2 cell embryo and one side developed normal embryo but other half dead cell
73 of 371
what experiment shows regulative development?
driesch, took sea urchin embryos at 2 cell stage used a fine babys hair to separate 2 cells and got smaller fully formed larva
74 of 371
what kind of development is unusaul?
75 of 371
why is regulative development more common?
cells signal to each other
76 of 371
is patterning in development autonomous or non-autonomous?
mixture of both!
77 of 371
what is autonomous mechanisms?
segregation of cytoplasmic components
78 of 371
what are non-autonomous mechanisms?
cells signalling to each other, uses receptors usually
79 of 371
why do we label cells?
to follow cell lineage and identify cell fates
80 of 371
what do cells pass through as they differentiate?
different states of commitment- specification, determination
81 of 371
what is an example of something that signalling between cells using receptors?
growth hormone
82 of 371
3 types of signalling?
1) diffusible signals with rec 2) juxtacrine signalling both on m 3) diffusible signals with intracellular recs (steroid hormones)
83 of 371
what is a morphogen?
chemical that gives rise to correct morphology, chemical (usally diffusible signal) forms a concentration gradient, produced from a localised source, usually sensed thro recs, cells respond diff to diff concentrations of morphogens
84 of 371
what is the french flag model?
colours-pattern of cell types you want to achieve, have a graded concentration of morphogen, concentration of morphogen depends on position of embryo
85 of 371
what development does the french flag model account for?
regulative dev
86 of 371
what happens if the line is cut in half in the french flag model?
system will regenerate
87 of 371
what is the bicoid mutant phenotype?
lacking head structures at anterior end
88 of 371
what did researchers hypothesize about the bicoid mutant?
there must be something at the anterior head that produces head structures
89 of 371
how did they test that hypothesis?
took cytoplasm from WT and transplanted it into anterior of bicoid mutant egg then some anterior structures develop
90 of 371
where is bicoid protein concentrated in the egg?
at the anterior end steep gradient towards posterior
91 of 371
whats more tightly held in the anterior part maternal bicoid mRNA or bicoid protein?
maternal bicoid mRNA
92 of 371
what is bicoid? what does it turn on?
a transcription factor, turns on hunchback but only above a certain conc
93 of 371
how do we know hunchback is dependent on bicoid?
if we look in a bicoid mutant theres hardly any hunchback
94 of 371
what kind of gene is a hunchback gene?
gap gene
95 of 371
where are maternal genes made?
in the nurse cells in the ovary
96 of 371
what is an example of a maternal gene?
97 of 371
whats the rle of bicoid?
activates zygotic genes, start dev of gap genes hunback, segmentation cascade
98 of 371
where does bicoid form a gradient?
in the synctial blastoderm just lots of nuclei in one cytoplasm, no cells yet
99 of 371
what is induction?
signalling from one cell type to another getting a change in responding cell (often specification)
100 of 371
what is the amphibian organiser?
cut out small piece of tissue from blastopore lip on dorsal side and transplant it to ventral side of another embryo
101 of 371
what result did the amphibian organiser give?
produced a second axis in the embryo
102 of 371
where was the secondary axis derived from?
the host tissue
103 of 371
what tissue was induced to form the axis?
the host tissue-responds to sigs
104 of 371
what effect does the timing of induction in the amphibian organiser have?
early gastrula- clear 2nd axis, late gastrula- less affected, longer you leave it less competent to respond
105 of 371
why is the tissue that induces a secondary axis called the speman organiser?
it organises the tissue around it
106 of 371
what is competence?
the ability of tissue to respond to a signal
107 of 371
what may competence involve?
expression of appropriate rec molecules
108 of 371
what is the xenopus animal cap assay?
cut out middle cells, put animal cap directly on vegetal cells
109 of 371
what happened in the xenopus animal cap cell?
cells like notochord and muscle were produced mesodermal cell fates that were usually made by the middle cells that were removed
110 of 371
what is the inducing tissue?
vegetal cells induce animal cap cells
111 of 371
what tissue is competent to respond in the animal cap assay?
animal cap cells
112 of 371
what are animal cap cells fated to be?
neural tissie
113 of 371
what are animal cap cells specified to be?
114 of 371
what can animal cap be induced to become?
muscle tissue
115 of 371
is FGF signalling necessary or suficient for limb bud formation?
necessary and sufficient
116 of 371
what kindof tissue is in thelimb bu?
meschenymal withetoderm on the outside
117 of 371
what isthe apical ectodermal ridge?
a ridge of thick epithelium around the limbud
118 of 371
what lost limbs in evolution
119 of 371
what is the role of the apical ectodermal ridge?
1) keeps limb bud flattened, 2) proliferation in the progress zone
120 of 371
what forms first in the chick the limb bud or axes?
121 of 371
what are limb buds?
appendages to the basic body plan
122 of 371
how many limbs do vertebrates usually have?
123 of 371
What happens if you dissect the apical ectodermal ridge off?
Limb dev outgrowth stops, only get proximal structures
124 of 371
What happens if you dissect the apical ectoderm ridge off at later stages?
More distal structures form, more outgrowth but no digits
125 of 371
what happens if you remove apical ectodermal ridge and replace it with FGF4 protein bead?
FGFs substitute for AER and allow outgrowth of limb
126 of 371
what is the fgfs in the AER signalling to?
the progress zone
127 of 371
what is the progess zone
a distal region of mesenchyme tissue
128 of 371
what is the progress zone derived from?
129 of 371
AER secretes FGF to progress zone what does this do in the progress zone?
undifferentiated cells rapidly divide
130 of 371
what does the length of time in the progress zone affect?
length of time determines cell fate
131 of 371
how did they test the role of the progress zone?
grafting experiments of old and young limb buds
132 of 371
what happens with an old stump with young tip?
duplicated some of the structures in middle of limb
133 of 371
what happens if you have a young tip with old stump?
distal elements attached to humerus
134 of 371
what is length of time in the progress zone setting?
the proximo-distal axis cell fate
135 of 371
short time in the progress zone produces what cell fate?
proximal cell fates
136 of 371
longest time in the progress zone gives what strucures
distal cell fates
137 of 371
how did they show FGFs were sufficient for limb bud formation?
FGF4 protein bead induced ectopic limb buds
138 of 371
whats the zone of polarizing activity
region of posterior limb bud mesenchyme which when transplanted under the AER induces symmetrical duplications of normal limbs along the AP axis
139 of 371
is the back of your hand ventral or dorsal?
140 of 371
what does transplanting the zone of polarising activity from posterior to anterior do?
gives mirror image
141 of 371
what axis does the zpa affect?
AP axis
142 of 371
what did they think might be in the zpa giving the mirror image?
143 of 371
what is being expressed in the zone of polarising activity?
144 of 371
how did they prove shh was in the zpa>
bead of shh to anterior did the same mirror duplication as the zpa transplant
145 of 371
what hox genes are expressed in nested domains in the limb bud?
hoxa and hoxd
146 of 371
what did deletion of hoxa and hodd do?
absence of shh expression and truncation of the limb
147 of 371
what is it thought that hoxa and hoxd do?
specify the zpa,where shh expression is going to be
148 of 371
a zpa graft sets up new expression of what
hox genes
149 of 371
what is therre a feedback loop of in the zpa
hox genes and shh expression
150 of 371
2 ways digits are formed?
1) differential growth (amphibians) 2) cell death mammals+birds
151 of 371
what controls the pattern of cell death?
152 of 371
transplantation exps of limb buds of chickens and ducks showed what?
the mesoderm of the limb determines pattern of cell death
153 of 371
if you take mesoderm from chick limb bud and ectoderm from duck what do you get?
a chick foot
154 of 371
if you put duck mesoderm with chick ectoderm the foot is what?
duck foot
155 of 371
what is cell death for digits regulated by?
hox genes
156 of 371
what is the wing of a bat?
its fingers!
157 of 371
why has snakes lost limbs?
expansion in domains of hox expression prevents FGF being expressed
158 of 371
how do we know FGF is necessary for limb bud formation?
KO of Fgf10 (ligand) or FGFR (rec) genes result in embryos lacking limb buds
159 of 371
what do hox genes do in limb bud formation?
restricts expressionof FGFs to limb forming regions
160 of 371
what does the hoxb5 KO mutant give?
limbs develop at a more anterior level
161 of 371
what is forward genetics?
mutant phenotype -> cloned gene
162 of 371
what is an example of reverse genetics?
mouse KOs
163 of 371
what is reversed genetics?
cloned gene -> mutant phenotype
164 of 371
what genes do mesoderm express?
twist and snail
165 of 371
what group of cells are set aside in the neuroectoderm (on ventral side)
proneural cluster
166 of 371
what genes do the proneural cluster express?
achaete and scute
167 of 371
AP axis triggered by what?
bicoid at anterior of embryo
168 of 371
what is the primary fate of he proneural cluster?
169 of 371
what is the secondary fate of the proneural cluster?
the epidermis
170 of 371
where is the neuroectoderm in the embryo?
ventral side
171 of 371
how does neuroectderm turn into a neuroblast?
lateral inhibition- inhibits the cells around it
172 of 371
what happens in homozygous loss of function mutants for notch and delta?
all cells in the proneural cluster become neuroblasts
173 of 371
what does it mean that the proneural cluster is an equivalence group?
all cells have an equivalent competence to form the neuroblast fate
174 of 371
what s the receptor notch or delta?
notch rec, delta-ligand
175 of 371
what kind of signalling is notch and delta?
juxtacrine signalling
176 of 371
what does the notch delta oathway do?
expresses genes by disocciating repressor
177 of 371
what is the notch delta pathway for lateral inhibition?
cell 2 expresses delta (ligand) more strongly, activates notch rec in cell 1 and notch pathway > down regulates delta in same cell as notch (cell 1) -> notch on cell 2 weaker, delta on cell 2 stronger
178 of 371
stronger delta signalling gives what cell?
179 of 371
cell with stronger notch activity gives what cell?
epidermal cell
180 of 371
what happens when cells are specified to become neuroblasts?
undergo a dramatic change in behaviour, lose junctions with epithelial neighbours, delamination, move into embryo, localising determinats
181 of 371
what determinants are localised to a neuroblast after specification?
segregation of cytoplasmic components- numb (before cell division) + prospero
182 of 371
how is the spindle in the neuroblast determined for cell division?
spindle forms perpindicular to where numb is placed
183 of 371
the cell with the numb segregation becomes what?
ganglion mother cell
184 of 371
what kind of divisions do neurblasts show?
185 of 371
what kind of fate division is assymetric division of neuroblasts?
autonomous cell fate as cytoplasmic segregation
186 of 371
what does the neuroblast remain?
a stem cell
187 of 371
what does the progeny of ganglion mother cell become?
188 of 371
what are mechanosensory bristles for?
mechanical movement like dust
189 of 371
whatis the bristle embedded in?
the socket cell
190 of 371
what encapsulates the sensory neuron in the sensory bristle?
the sheath cell
191 of 371
what are the parts of the sensory bristles?
sensory neuron, hair cell, socket cell, sheath cell
192 of 371
where are the proneural clusters for the sensory bristles?
imaginal discs
193 of 371
what are the imaginal discs for?
adult structures in the fruit fly
194 of 371
what is the precursor for the sensory bristle?
sensory organ precursors
195 of 371
what singles out sensory organ precursors from proneural clusters?
delta-notch signaalling
196 of 371
the cell with more what becomes the neuroblast
197 of 371
how does the sensory bristle cells form?
Sensory organ precursors are singled out from proneural clusters by delta-notch signalling it is then undergoes further divisions
198 of 371
what does 2a from SOP form?
socket and hair cell
199 of 371
what does 2b give rise to?
sheath and neuron
200 of 371
how does a SOP divide?
asymetric division in plane of epithelium
201 of 371
the SOP cell divides, the cell with numb becomes what?
a 2b cell (sheath and neuron)
202 of 371
what is the function of numb?
inhibits notch function
203 of 371
what cells have high notch activity from divsion of SOP?
2a and socket and sheath
204 of 371
loss of notch (high numb inhibits) gives what?
4 neurons
205 of 371
too much notch (less numb) gives what?
4 socket cells
206 of 371
what is each sensory bristle organ?
a clone of 4 cells
207 of 371
where does the 4 cell of the sensory bristle derive from?
sensory organ precursor
208 of 371
how are sensory organ precursors singled out from proneural clusters in the imaginal discs?
lateral inhibition, delta-notch signalling
209 of 371
what is at the end of the axon?
the growth cone
210 of 371
how many growth cones are sent out from one axon?
multiple then refined
211 of 371
what happens to excess connections?
they are pruned back to get a 1:1 correspondance
212 of 371
what is the growth cone made of?
213 of 371
how does the growth cone find the other cell?
chemoattraction and chemorepulsion- diffusible molecules long distance cues
214 of 371
if a chemoattraction is about what happens to growth cone?
moves up the concentration gradient
215 of 371
what are diffusible short range cues in axon guidance?
contact mediated cues like pros on the cell surface like cadherins and Eph ligands- attractive or repulsive
216 of 371
are cadherins contact mediated cues attractive or repulsive?
217 of 371
what is an example of contact repulsion~?
Eph ligands
218 of 371
what happens to the num of neurons during dev?
generated in excess then pruned away only those with connections will survive
219 of 371
what are neutrophic factors needed for?
neuronal survival
220 of 371
what does neuronal neutrophic factors specifically do?
ensure num of neurons = num of targets
221 of 371
what does the growth cone send out?
filopodia-exentio of cell m
222 of 371
stages in zebrafish dev?
egg surrounded by chorion -> yolk-free cytoplasm+yolk -? blastoere and yolk -> morula->blastocyst
223 of 371
what is dev?
a change in structure (anatomy+morphology over), how single cell devs into a fully formed organism with many cell types
224 of 371
what is regional specification?
how a pattern appears in a similar population of cells
225 of 371
what side is your tummy ventral or dorsal?
226 of 371
what does morphogenesis requre?
cell and tissue movement
227 of 371
what is morphogenesis?
shaping of organs and tissues in 3d
228 of 371
what does cell diffentation require?
cell-type specific gene products, differential gene transcription
229 of 371
what is the broad diffention of cell differentation?
formation of specialised cell types
230 of 371
what do many embryos absorb to grow?
the yolk
231 of 371
what does growth involve?
cell death and cell proliferation
232 of 371
differentiated cells start off as what?
stem cells
233 of 371
what model organisms are used for model organisms?
chick and frog
234 of 371
why do we need model organisms?
to identify genes with roles in dev processes, understand gene function, provide models for human disease
235 of 371
what model organisms are used in dev genetics?
fish, mouse, worm, fly
236 of 371
why is it okay to apply some model organism stuff to humans?
conservation of body plan, conservation of genes and gene function
237 of 371
what kind of disease is aniridia?
autosomal dominant
238 of 371
consequences of aniridia?
lack of iris, decreased vision and cataracts
239 of 371
what is the homozygous phenotype for aniridia?
homozygous perinatal lethal
240 of 371
what gene is mutated in aniridia?
241 of 371
what year was PAX6 associated ith human and mouse developmental abnormalities (aniridia, small eye)
242 of 371
what is the mutation in aniridia?
semi dominant- intermediate phenotype
243 of 371
running order of genes being turned on?
maternal gene -> gap genes -> pair rule genes -> segmentation genes
244 of 371
when were paired genes found to be a key regulator in drosophila dev?
245 of 371
gene in the mouse first identified simple to paired genes in dropsophila IN 1988?
246 of 371
How many PAX genes were found in the mouse by 1991?
247 of 371
what is small eye caused by?
mutations in pax 6 gene
248 of 371
what did pax 6 mutations in drosophila map to?
eyeless mutation- no eye
249 of 371
in 1995 ectopic pax6 induces what in drosophila?
an ectopic eye (so does the vertebrate)
250 of 371
homeodomain of pax6 structure?
3 alpha helices 1 in major groove of DNA, crystal structure of paired domain similar
251 of 371
how many mutations are there in pax6 characterised?
252 of 371
what is conserved?
gene sequence and function
253 of 371
how were pax family genes first discovered?
by genetic studies in flies
254 of 371
what does PAX6 gene code for?
a TF
255 of 371
is PAX6 neccessary or sufficient for eye formation in the embry?
necessary and sufficient
256 of 371
pax6 gene sequence are what from flies to humans?
highly conserved
257 of 371
what is making a targetting construct?
disrupt gene like pax6 by introduce another gene (drug resistance)right in the middle of he genes exon
258 of 371
what is homologous recombination?
done in embryonic stem cells recombination event 2 strands dna cross over , target dna and targetting gene cross over
259 of 371
how into every cell of the mouse
homologous recombination in embryonic stem cells,
260 of 371
what stage are the stem cells in?
blastocyst stage cells before implantation of embryo (
261 of 371
what tissue becomes the embryo itself?
the epiblast
262 of 371
what does the trophoblast make?
extra embroyinc tissue, placenta and membranes
263 of 371
what is ES?
undifferentiated in cultured cells
264 of 371
how do you replace pax6 gene with targetting construct?
treat cells, DNA into nucleus by homology seq similarity it will find similar sequences very rarely have recombination event 2 strands dna cross over
265 of 371
how do we tell which cells took up the targetting construct?
selection in antibiotic/drug as targetting construct has gene resistance
266 of 371
what happens with the stem cells that have the gene knocked out?
replace cells in blastocyst by microinjection (fine glass pippette) -> blastocyst into foster mother
267 of 371
what is a chimera?
has some cells with mutation in cells only one allele (+/-) heterozygous for mutation
268 of 371
what is the marker in chimera mice usually?
colour coat patches
269 of 371
how do you get a heterozygote with all cells being mutant?
chimera x wild type
270 of 371
how do you get a homozygous knockout?
breed brother and sister with all cells being mutant
271 of 371
why is the mouse particularly used for knockout?
you can get embryonic stem cells from them
272 of 371
what KO models of human disease are there?
cystic fibrosis, atherosclerosis, susceptibility to cancer
273 of 371
what characteristic of zebrafish allows easy characterisation of mutant phenotypes and visualisation of labelled cells?
274 of 371
what does early embryogenesis involve?
gametogenesis, fertilisation, cleavage, formation of a blastula, generation of cell differences, germline and somatic cells, zygotic genome activation
275 of 371
what was the problem when looking at differentation?
how do chromosomes (identical in every cell) direct differences between the cytoplasmic contents of different cells
276 of 371
what does pluripotent + mulipotent mean?
multiple cell fates
277 of 371
what does totipotent mean?
can form embryonic and extra embryonic cells
278 of 371
what does pluripotent mean specifically?
any cell in the embryo but not extra embryonic tissue
279 of 371
hypotheses to explain a restriction in potency?
gene loss, diferential gene activity
280 of 371
what did lens regeneration in the newt show?
iris cells retain genes to turn on cystallin, only lens express crystallin genes
281 of 371
put human liver cell in rat muscle what happens?
liver cell turns on human muscle specific genes, liver genes switched off
282 of 371
pleurodeles (newt) oocyte put in xenopus (frog) kidney cells nuclei in what happens?
1st) kidney specific genes switched off 2) re-expressed oocyte specific genes for xenopus
283 of 371
what is the method in the last few cards called?
nuclear transfer
284 of 371
what is the newer technique to see if genes are still present?
genomic sequencing-see muscle genes in WBCs
285 of 371
what do you find in the genome?
the entire genome stays in tact in the human-no gene loss
286 of 371
what do nuclear transfer experiments tell us?
gene expression in nuclei from differentiated cells can be changed, gene expr can be controlled by cytoplasmic factors, genes are not lost
287 of 371
what do cells lose as they differentiate?
288 of 371
if the nuclei retain the whole genome do they remain totipotent, who tested this?
briggs and king
289 of 371
what did briggs and kinds do in their nuclear potency experiment?
took a fert egg + extracted cytoplasm (with chromosomes), replaced genetic material with nucleus taken from a blastocyst stage embryo, generated normal Rana (tadpole)
290 of 371
what did briggs and kings conclude?
early blastula nuclei in rana are pluripotent, got tadpoles but not adults
291 of 371
what did doing it at each stage of the embryo show?
the later in dev eg neurula the less potency the nucei had
292 of 371
what happens to nuclei as we develop?
they lose potency
293 of 371
hat did gurdon do to test nuclear potency?
took nuclei from cells of guts in tadpoles put it in a unfertilised egg that had its chromosomes irradiated by UV to destroy DNA,
294 of 371
what genetic marker did gurdon use?
gut cell nuclei from albino tadpole, unfertilised egg from pigmented frog
295 of 371
what happened to the embryo in gurdons experiment?
only half the blastocyst were dividing so did serial transfer (nuclei from dividing into new eggs) got clones of genetically identical tadpoles = allalbino (from gut cell nuclei)
296 of 371
what did gurdon conclude from this?
nucleus retains entire potency to form all the different cell types
297 of 371
critisims of gurdons gut cell exp?
not fully differentiated stem cell like gut regenerated, low success rate no adults from germ cells
298 of 371
briggs and king nuclear potency exp?
needle take out dna in fert egg -> nucleus out of blastula stage egg -> generated normal tadpole
299 of 371
why was rhe nuclei pluripotent not totipotent?
no adults so cant have all info to gen adult
300 of 371
gurdon nuclea transfer in zenopus gut cell exp?
destroy dna in egg by uv irration -> replace with gut cell nucleus, albino gut cell, pigmented egg -> serial transfer into other eggs
301 of 371
nuclear potency gurdons ADULt cell experiment?
keratin expressing skin cells -> take out nucleus -> transfer into irradiated egg -> serial transfer -> genetically identical clones
302 of 371
what was the conclusions from gurdons 2nd experiment?
nuclei of differentiated adult skin cells can be reprogrammed to become pluripotent
303 of 371
how do you clone sheep?
mammary epithelial cells grown in culture low serum (white) -> unfertilised egg chrs removed with needle (blackface ewe) -> fusion by electric current -> nucleus of mammary cell in egg -> embryo culture -> implant in foster mother
304 of 371
what were the mammary cells grown in? why?
low serum -> cells exit mitosis go into G0 best for cloning
305 of 371
how do you check the authentity of clones like dolly?
DNA fingerprinting like microsatellite analysis or dna sequencing
306 of 371
what did gurdon receive an award for finding out?
the discovery that mature differentiated cells can be reprogrammed to become pluripotent
307 of 371
what did jacob and monod understand from their bacterial genetics?
problem with embryology is why cells dont express all of the time everything they can in their genome
308 of 371
conclusions of stem cells and potency?
most cells lose potency during dev, stem cells can remain multipotent, nuclei retain potency
309 of 371
what happens in V J and C regions in immunoglobin genes?
lose genes in immunoglobins by gene rearrangements in b lymphocytes
310 of 371
what organism has chromosome diminution (gets rid of chromosomes during development?
311 of 371
how do they germ cells in the parascaris keep all genome in the germ cells?
has germ plasm -> cells that inherit this become germ cells -> retain chromosomes but somatic cells fragment their chromosomes they dont need
312 of 371
win the dorsoventral axis what is the difference between where neural tissue is in insects and vertebrates?
Insect- ventral, vertebrates: dorsal
313 of 371
what axis does bicoid set up?
AP axis
314 of 371
blastoderm stage is what?
surround yolky filled interior, nuclei all migrated and membranes have come down
315 of 371
what is the dorsal ectoderm going to become?
316 of 371
where is mesoderm of fly?
ventral side
317 of 371
what is in between the dorsal ectoderm and mesoderm?
318 of 371
how is the DV axis of embryo established in the oocyte?
AP+DV pattern already, egg chambers grow-multiple chain, end is ost mature oocyte with nurse cells at anterio, nucleus always anterodorsal
319 of 371
what are follicle cells for?
important signalling role, not laid with the egg
320 of 371
what maternal effect mutants affect DV pattern?
dorslaised and ventralised class
321 of 371
what are the dorsalised class of mutant caused by?
spatzle, toll and dorsal STD
322 of 371
what are dorsalised class of genes required for?
ventral cell fates in the fruit fly
323 of 371
what genes are mutated for the ventralised mutants?
324 of 371
hat are ventralised mutant genes needed for?
development of dorsal cell fates
325 of 371
what does epistasis analysis do?
order genes into a pathway
326 of 371
what is the toll pathway?
spatle --> toll --/ cactus --/ dorsal (STCD)
327 of 371
what is the ligand in the toll signalling pathway?
328 of 371
where is spatzle?
in the perivitelline space of ventral side of embryo
329 of 371
what is toll?
transmembrane recptor
330 of 371
what gets broken down when toll is activated?
cactus degraded
331 of 371
what does cactus do?
binds to dorsal holds it in cytoplasm
332 of 371
what does toll do to catcus?
inhibits it from holding dorsal, degrades it
333 of 371
what is dorsal?
a transcription factor
334 of 371
where does dorsal move to when cactus gets degraded?
into the nucleus, change of gene expression
335 of 371
how is dorsal distribued in the egg?
it is distributed uniformly (maternal factor)
336 of 371
what side does dorsal enter the nuclei on?
ventral side
337 of 371
why does it only enter on the ventral side?
spatzle is only on ventral side, reflects DV patterning of the egg chamber, set up by signalling between oocyte and follicle
338 of 371
dorsal is a TF what does it turn on?
zygotic genes in the mesoderm (on ventral side) like twist and snail
339 of 371
what does dorsal TF repress?
represses transcription of dorsal cell fates egg dpp
340 of 371
why can dorsal act on these genes?
they have binding sites on twist+snail(mesoderm on ventral), rhomboid(middle) and dpp (dorsal)
341 of 371
what does dorsal act as?
a morphogen so respond to different thresholds of dorsal pro conc\
342 of 371
wherre ie twist oly activated?
ventral side of the embryo
343 of 371
what is dorslal an activator for?
rhoboid, twist and snail
344 of 371
what is dorsal a repressor for?
345 of 371
affinity for dorsal is high or low in twist and snail?
low afinity so need lots to activate
346 of 371
does rhomboid and dpp have high or low affinity for dorsal?
high affinity therfore only need a little bit
347 of 371
what does neuroectoderm gene?
348 of 371
what gene is for dorsal ectoderm?
349 of 371
what for ventral mesoderm?
twist and snail
350 of 371
what happens in a ventralised mutant?
cactus cant hold dorsal in cyto (mutation in cactus) dorsal pro moves into nuclei of all cells in embryo
351 of 371
what genes are activated throughout the whole embryo?
twist and snail
352 of 371
all cells adopt what fate in teh ventralised mutant?
ventral cell fate
353 of 371
what happens in a dorsalised mutant?
dorsal doesnt enter the nuclei, dpp expressed throughout, twist and sbnails not expressed, all cells dorsal fate
354 of 371
dpp is what?
signalling molecule it forms a morphogen gradient (high in dorsal regions)
355 of 371
what does dpp have?
its own pathway with recs and signalling cascade
356 of 371
what happens in gastrulation?
mesoderm invaginates and moves in the embryo (forms msucle) neuroectoderm covers ventral side, neuroectoderm top dorsal side
357 of 371
what is the role of the toll pathway?
innate immune response in fly
358 of 371
what is the toll pathway stimulated by?
bacteria and fungal infection in adult flies
359 of 371
where are toll like receptors expressed on?
360 of 371
what is the toll pathway required for?
the innate immune repsonse to microbial infection (bacterial and fungi)
361 of 371
what does the toll like rec bind to?
proteins on fungi, bacteria, parasites or viruses
362 of 371
what happens when they bind to a toll rec?
stimulate toll pathway, changes in gene expression in nucleus, eg inflammatory cytokines
363 of 371
what does the antigen and toll like rec do?
gets eaten in phaglysome
364 of 371
what is the human homologue of Dorsal?
365 of 371
what is the homologue of cactus?
366 of 371
what does I-kb do to NF-KB
I-KB sequesters and holds NF-KB in the cytoplasm
367 of 371
what does NF-KB regyulate?
gene expression in B cells of the immune system
368 of 371
what is the dpp homologue?
bone morphogenetic protein
369 of 371
what is bone morphogenetic protein for?
formation of bone, plays a role in the DV patterning of the vertebrate
370 of 371
if BMPs get out of hand and dysregulated and muscle turns into skeleton what disease do you get?
fibrodysplasia ossificans progressiva
371 of 371

Other cards in this set

Card 2


what was Briggs and Kings experiment for nuclear potency?


used Rana(frog), needle to extract chrs out of egg cell, egg cell with no GM, replaced GM with nucleus from cell in blastula stage embryon--> normal tadpole, blastula nucleus pluripotent

Card 3


what are the 2 hypotheses to explain why cells lose potency?


Preview of the front of card 3

Card 4


what experiments show that genes are not lost when cells differentiate, expression controlled by cytoplasmic factors and gene expression of differentiated can be changed?


Preview of the front of card 4

Card 5


what happens in lens regeneration in newts?


Preview of the front of card 5
View more cards


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Development resources »