Monsters. Flashcards
What is responsible for forming human monsters?
Genetic mutations.
What is responsible for forming human monsters?
Genetic mutations.
How did researchers conclude which genes caused which mutations?
By experimenting on other organisms that have a simiilar developmental process to humans.
What techniques were used on what animals?
Gene knockout technique. Mice.
Antisense technique. Zebrafish.
SiRNA silencing of RNA. C. elegans.
Induced mutations. Many species
Once researchers had performed gene knockouts on organisms, what did they do?
They allowed the organism to develop so they could see what happened.
How do researchers look at a genetic defect that is unique to humans?
Find and study humans that have this mutation.
Buddhists used to use what kind of mutants a godlike creatures?
Dwarves.
They were guardians of buddhist temples.
What can cause dwarfism in humans?
Environmental causes.
Genetic causes.
What is the common name for dwarves?
Achondroplastic dwarves
What is the mutation that leads to dwarfism?
Achondraplasia.
What is the gene that is affected by achondraplasia?
Type 2 collagen.
What does the type 2 collagen mutation lead to?
The impaired synthesis of sulphated proteoglycans.
What does the type 2 collagen gene code for?
Cartilage and bone formation.
What are hormonal causes of dwarfism?
The gene that releases hormones from the pituitary gland is affected.
Why are hormones important for growth?
Hormonal regulation is important for stimulating the growth of the longer bones.
Mutations that affect growth factors will lead to what?
Dwarfism.
How did researchers conclude which genes caused which mutations?
By experimenting on other organisms that have a simiilar developmental process to humans.
Buddhists used to use what kind of mutants a godlike creatures?
Dwarves.
They were guardians of buddhist temples.
What is cretinism?
An example of environmental dwarfism.
What causes cretinism?
When a person does not get enough dietary iodine.
When a person does not get enough iodine, what part of the body is affected?
Thyroid function.
Salt in developed countries is enriched with what?
Iodine.
The monster of Ravenna is likely to have had what disease?
Roberts syndrome.
What are the characteristics of Roberts syndrome?
Autosomal recessive.
Long bone deficiencies (loss of proximal structures).
Cleft palate.
Malformed hands.
Chromosomal abnormalities.
Mitotic errors.
Changes in heterochromatin.
How does Spemman and Mangolds experiment related to the creation of 2 headed animals?
They transplanted the dorsal lip of the blastopore onto the other side of the embryo.
The nodal related proteins in the dorsal lip inactivate BMP and generate a second dorsal axis.
What is the most common form of 2 heads being exhibited in humans?
Siamese twins.
How are identical siamese twins formed?
The embryo splits at the blastomere stage, cells will regulate each other to develop a new organism, once they re-fuse, their will be 2 separate but identical groups of cells that are joined together.
How are non identical twins formed?
Where 2 different embryos fuse together.
Who were 2 famous womanising Siamese twins?
Cheng and Eng.
Who were the Siamese twins who shared a pair of legs?
The Tocci brothers.
What did French surgeon Ambrose Pare blame for causing Siamese twins?
God, the devil.
What women saw during pregnancy.
tight womb.
Tight clothes worn by the pregnant women.
Who started a mutant museum and started to look into why mutants were formed?
Geoffrey St Hilaire.
Where were mermaids first described?
In Japanese and Greek mythology.
What genetic defect causes a mermaid like appearance?
Sirenomelia.
What are the symptoms of sirenomelia?
The legs fuse together and form a tail like structure.
How can sirenomelia be induced in golden hamsters?
By exposing embryos to heavy metals such as lead and cadmium during certain periods in their development.
How can sirenomelia be induced in mice?
By exposing a mouse embryo to retinoic acid.
What is a cyclops?
A monster with only one eye in its head?
How can cyclopia be induced in a calf?
If a pregnant cow ingests a plant called veratrum californium on the 14th day of gestation, then the calf will be born with one eye.
As a drug in the plant disrupts SHH signalling.
How does SHH cause 2 eyes to be formed?
It is secreted from the prechordal plate is responsible for splitting the eye field into 2 fields.
Which drug can induce cyclopia?
Cyclopamine.
It is a steroidal alkaloid which is similar to cholesterol.
How does cyclopamine induce cyclopia?
By inhibiting target tissues that respond to SHH.
What is the most common cause of cylopia in humans?
Holoprosancephaly.
Holoprosancephaly leads to a mutation in which gene?
The SHH gene.
If a baby is born with cyclopia, what other condition are they likely to have?
Trisomy 13.
Where is the SHH gene located in humans?
On the long arm of chromosome 7.
WHy does SHH need a receptor?
Becuase it is a secreted protein.
What is the receptor called for SHH?
PATCHED.
What is the membrane receptor that PATCHED works with?
SMOOTHENED.
What happens when SHH is bound to PATCHED?
If SHH is bound to PATCHED, then this will activate SMOOTHIN.
What happens when SHH is not bound to PATCHED?
When no SHH is bound to the PATCHED receptor then SMOOTENED is inhibited.
What happens when PATCHED is activated?
It will turn on the GLI proteins.
These bind to genes and turn them on, e.g. the HOX genes.
Heterozygous mutations of SHH are caused by what?
One form of autosomal dominant holoprosancephaly.
What do less mild forms of holoprosancephaly cause?
A range of different phenotypes associated with the face from cyclopia to a single incisor.
Who was the God with 2 faces?
Janus.
How can animals and humans develop 2 faces?
An increase of SHH in the frontal nasal prominence which promotes mediolateral expansion the face and ventral forebrain.
The condition that causes a person to have 2 faces is called what?
Hypertelorism.
How can hypertelorism be induced in chickens?
It can be induced in chickens by implanting a bead soaked with SHH into the frontal nasal prominence.
Too much SHH causes what?
Too little SHH causes what?
Too much SHH causes 2 faces to develop.
Too little SHH causes cyclopia.
What is the real name of ostrich foot mutation?
Split hand/foot malformation or electrodactyl.
What characterises electrodactyl?
It is typically characterised by a cleft in the hands or feet and a fusion of fingers or toes.
What causes electrodactyl?
A mutation in the DLX gene which is the master control gene for limb development.
How did researchers induce electrodactyl in mice?
They did a double knockout in mice as they have a double copy the DLX gene.
They targeted DLX-5 and DLX-6 and this knockout caused the split hand/foot malformation.
What is acheiropody?
An autosomal recessive genetic defect and is the absence of a hand or foot.
Acheiropody is common in people of what descent?
Portuguese.
What kind of structures do not form when a person has acheiropody?
Distal structures.
Hands/feet.
What is thought to cause acheiropody?
It has been mapped to a gene called LMBR-1 and is thought to encode a receptor.
It is also possible that this disorder is disrupting the formation of the AER or FGF signalling.
What is phocomelia?
The loss of proximal structures (arms/legs).
Do any limbs form when a person has phocomelia?
Hands and legs grow out of the shoulders and pelvis.
Which drug was responsible for causing phocomelia?
Thalidomide.
What does polydactyly cause?
A mirror image hand to develop.
What is the most common genetic defect that leads to polydactyly?
An SHH mutation which affects GLI-3.
How can polydactyly be induced?
By transplanting a ZPA to the anterior limb bud.
Polydactyly occurs in how many live births?
10-15/1000 births.
What are supernumerary breasts?
Where a person has extra breasts or nipples.
What causes supernumerary breasts?
It is a genetic trait.
Where are the human orthologs?
The human orthologs are in the HOM-C, HOX clusters.
