concepts and terminology

Question 1

what causes a change in cell fate?

Answer 1

changes in cell fate is a consequence of the molecular character of particular cells

Question 2

how are these changes controlled?

Answer 2

Mosaic development - information inherited by parent cell to tell it what to become
regulative development - the cell is influenced by it’s surroundings, or position, within the embryo - a cell does not know what it will become until it has received a particular type of information or arrived at a particular location which determines its future

Question 3

explain Roux’s experiment

Answer 3

Roux has destroyed one cell of a 2 cell frog embryo but did not remove it resulting in the development of only one half of the embryo. this was to represent mosaic development however it can be perceived as regulative development as its environment affected it. The choice of development can be determined by how you do or interpret the experiment

Question 4

what is robustness?

Answer 4

a cell/ particular group of cells is damaged during development and the cell is able to detect/ sense that and compensate for it

Question 5

What does Driesch’s separation of sea urchin blastomeres demonstrate?

Answer 5

Driesch’s separation of sea urchin blastomeres demonstrates regulative development

Question 6

What is fate?

Answer 6

fate is what will normally happen to a cell during development

Question 7

What does commitment comprise of?

Answer 7

Specification - what tissues will develop in an autonomous (neutral) environment
Determination - an irreversible change in potential

Question 8

what is differentiation?

Answer 8

A restriction of potential with molecular/ biochemical changes - term often used for mature cell types

Question 9

What is potential or potency?

Answer 9

the range of tissues which a cell can give rise to

Question 10

what is totipotent?

Answer 10

can give rise to all tissues (a fertilised zygote up to an 8 cell stage)

Question 11

What is pluripotent?

Answer 11

Can give rise to many tissues

Question 12

What is orthotopic graft?

Answer 12

Transplantation of a tissue or organ into its normal anatomic position

Question 13

What is heterotopic graft?

Answer 13

Transplantation of a tissue or organ into a position that it normally does not occupy

Question 14

During an experiment using a labeled donor:

What will happen if you graft the labeled donor cells onto an embryo via orthotopic graft?

Answer 14

It will end up in its normal fate

Question 15

During an experiment using a labeled donor:

What will happen if you isolate the tissue?

Answer 15

You can find its specification

Question 16

During an experiment using a labeled donor:

What will happen if you heterotropically graft the labeled donor cells onto an embryo at its early stage?

Answer 16

it will lead to no determination as the early tissue isn’t committed

Question 17

During an experiment using a labeled donor:

What about at a later stage?

Answer 17

Determination will occur as the early tissue is committed

Question 18

What is induction?

Answer 18

Process by which cells and tissues in embryos direct the development of adjacent cells

Question 19

What does restriction in potential depend on?

Answer 19

Restriction in potential often depends on inductive interactions from neighbouring cells

Question 20

What is competence?

Answer 20

competence is the ability to respond to an inductive signal

Question 21

What does Spermann and Mangold’s classic 1924 experiment define?

Answer 21

Spermann and Mangold’s classic 1924 experiment defined an inducing tissue with organiser activity

Question 22

What does permissive induction create?

Answer 22

Permissive induction would create the environment where other factors can act to cause a tissue to be induced

Question 23

What are the two types of instructive induction?

Answer 23

Appositional - where the instructions is passed by the close apposition or bringing together of 2 different tissue types
Morphogen gradient - localised signal of morphogen which is diffusible from its localised source. as a result of this diffusion, there are different concentrations of morphogen across the embryo

Question 24

What is a morphogen?

Answer 24

A diffusible molecule that triggers different cell fates at different concentrations

Question 25

What can morphogens provide?

Answer 25

positional information within the embryo

Question 26

What do homeotic/ hox genes confer?

Answer 26

Hox genes confer positional identity

Question 27

What does the drosophila antennapedia have instead?

Answer 27

Has legs instead of antennae

Question 28

What do homeotic genes do?

Answer 28

Regulate the development of anatomical structures

Question 29

What do Turing’s reaction - diffusible model propose?

Answer 29

This proposes a diffusible activator that activates a diffusible inhibitor itself

Question 30

What are Turing’s patterns?

Answer 30

If the activator diffuses, it induces an inhibitor that also is diffusible. This inhibitor inhibits the activator. As there’s no activator now there’s no need for an inhibitor so it disappears.

Question 31

What are the steps to form a protein?

Answer 31

Regulatory region assembles RNA polymerase to generate RNA. RNA is transcribed and produces hnRNA containing both introns and exons. RNA is spliced leaving exons with a 3’ A tails and 5’ cap. RNA is translated then into a protein.

Question 32

What are the changes in cell fate reflected by?

Answer 32

Changes in cell fate are reflected by changes in gene expression

Question 33

What secretions allow cells to communicate?

Answer 33

secreted factors and other signals allow cells to communicate

Question 34

What other levels does additional control occur at other than gene expression?

Answer 34

Additional control at level of translation, post translation, epigenetic changes