Introduction Flashcards
How much will the population grow between 2015 to 2020?
By 3%
Between 2015 to 2020 how much will the populations of a) over 65
b)over 85
grow by?
a) 12%
b) 18%
What are the two theories of developmental biology?
Aristotle and Epigenesis
Nicolas Hartsoeker and Preformatisation
What is the preformatisation theory?
The belief that organisms develop from miniature versions of themselves
ie the homunculus = little man
Who proposed the cell theory?
Robert Hooke 1665
What are the three parts to the cell theory?
1) All organisms are composed of one or more cells
2) The cell is the most basic unit of structure, function and organisation of all organisms
3) All cells arise from pre-exisiting cells
Who proposed the germ plasm determinants theory?
Friedrich Leopold August Weismann 1880s
What are the 2 main types of cells?
Germ cells and somatic cells
Heritable information is transmitted by which cells?
Germ cells in the gonads and NOT somatic cells
What are the two types of development?
Mosaic and regulative
Who came up with the theory of mosaic development?
Weissmann?
What is regulative development?
The fate of a cell depends on its interaction with neighbours, not what piece of cytoplasm it has.
A blastomere is isolated early in cleavage to be able to form the whole individual
What is mosaic development?
Cell fate is determined by the components of the cytoplasm found in each blastomere
Which experiment shows mosaic development?
Roux’ s exeriment on the frog embryo
Half the embryo killed at the 2 cell stage = only half of the embryo develops
The cell was killed but was left in contact with the remaining cell
Which experiment shows regulative development?
Dreisch’s experiment on the sea urchin embryo
Separated at the 2 cell stage and the 4 cell stage
2 or 4 smaller larvae develop
