Term
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Definition
Gastrulation – a deeply conserved process in animal embryogenesis.
•Involves cell movement.
•Establishes early restrictions to developmental potential.
•Key step in early differentiation.
•Establishes the tripoblastic embryo. |
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Term
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Definition
A nuclear transplant experiment in frogs/toads that showed the cytoplasm contained factors that can control gene expression in the nucleus.
Conclusions:
1. The cytoplasm of the egg must reprogram the genetic potential of the
transplanted nucleus.
2. The mechanism of restriction of
potential during normal development IS
NOT irreversible genetic change |
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Term
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Definition
| can differentiate into any cell type or embryo |
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Term
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Definition
organism produced asexually from one ancestor to which they are genetically identical
F.C STeward worked with carrot plants and found out that root cells could grow into normal adult plants |
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Term
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Definition
| the growth phase of biological structures in an organisms |
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Term
| Timing of key developments stages for human embryos |
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Definition
Day 1 - Fertilisation in oviduct – cell divisions (cleavage) start.
Day 4 – get to the uterus.
Day 7 – ball of cells with cavity – blastocyst.
Day 12 – implanted into endometrium of uterus.
Week 2 – 4 nutrient directly from endometrium. Differentiation and development.
Week 4 – heart starts beating.
Week 5 – placenta has developed (estrogen and progesterone).
End of 1st trimester most development and organogenesis complete |
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Term
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Definition
outer layer
of cells. Does not
contribute to embryo – only
the placenta.
Trophoblast secretes enzymes –
breaks down molecules in
endometrium.
Blastocyst invades endometrium.
Trophoblast proliferates into
endometrium. |
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Term
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Definition
Inner cell mass form two layers –
epiblast(gives rise to embryo) and hypoblast. |
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Term
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Definition
| Stage after Blastula, three divisions, Ectoderm, Endoderm and Mesoderm |
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Term
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Definition
Trophoblast, Amnion, Chorion and Extra-embryonic mesoderm – placenta
Yolk sac and allantois – umbilical chord. |
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Term
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Definition
| All animals have tissues derived from three “germ layers”. Endoderms develop into the gut, liver, lungs. The Mesoderm develops into the skeleton, muscle, heart, kidney, blood . The Ectoderm develops into skin and nervous system. |
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