Concepts and terminology

Question 1

What are changes in cell fate accompanied by?

Answer 1

-Changes in cell fate are accompanied by molecular changes

Question 2

What are the 2 options that restriction in cell fate is controlled by?

Answer 2

• Option 1 Mosaic development(cell autonomous specification)
• Option 2 regulative development(conditional specification)

Question 3

What is Option 1 Mosaic development(cell autonomous specification) ?

Answer 3

Information is inherited from parental cell

Question 4

What is Option 2 regulative development(conditional specification)?

Answer 4

Cell influenced by its surrounding, or position, within the embryo

Question 5

What is Weismann’s nuclear determinants.?

Answer 5

• We have a once cell embryo and with 4 different factors
• After the first cell division/cleavage, the factors are inherited differently by the 2 daughter cells
• After the second division, each of the 4 cells, each of the cells inherit a different factor.

Question 6

What is Roux’s experiment on determination?

Answer 6

• We take a fetilised frog egg and divided into daughter cells
  
  • First clevage happens down the midline of the embryo
• Roux put a hot needle in the left blastomere and that caused that cell to die.
• This resutled in a normal half embryo on the right hand side and dead tissue on the left

Question 7

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

Answer 7

Driesch’s separation of sea urchin blastomere’s demonstrates regulative development

Question 8

What do the Aba and Abp cells in early C elegans larva give rise to?

Answer 8

-Early C elegans embryos that pharyngeal tissue will be derived from the Aba cell and its sister cell Abp will give rise to muscle in trunk or tail region of the embryo

Question 9

What happens if you flip the position of Aba and Abp cells?

Answer 9

If you flip the position of Aba and Abp cells, you find blue tissue will give rise to tissue in the head and the red cell will give rise to tail region

Question 10

What does fate mean?

Answer 10

What will normally happen to a cell during development

Question 11

What does commitment comprise of?

Answer 11

• Specification

- Determination

Question 12

What is specification?

Answer 12

What tissues will develop in an autonomous environment

Question 13

What is determination?

Answer 13

-An irreversible change in potential

Question 14

What is differentiation?

Answer 14

A restriction of potential with molecular/biochemical changes

Question 15

What do totipotent cells give rise to?

Answer 15

Totipotent can give rise to all tissues

Question 16

What do pluripotent cells give rise to?

Answer 16

Pluripotent can give rise to many but not all tissues

Question 17

What does restriction in potential depend on?

Answer 17

Restriction in potential often depends on inductive interactions from neighbouring cells

Question 18

What is competence?

Answer 18

Ability to respond to an inductive signal

Question 19

What does spemann and mangolds classic 1924 experiment define?

Answer 19

-Spemann and mangold’s classic 1924 experiment defined an inducing tissue with organiser activity

Question 20

What does permissive induction create?

Answer 20

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

Question 21

What are the 2 broad types of instructive induction?

Answer 21

• Appositional

- Morphogen gradient

Question 22

What is appositional instructive induction?

Answer 22

-This is where the instruction is passed by the close apposition or bringing together of 2 different tissue types

Question 23

What is morphogen gradient instructive induction?

Answer 23

• Localised signal of morphogen
• That morphogen is diffusible and diffuses from its localised source
• As a result of that diffusion there are different concentrations of the morphogen across the embryo

Question 24

What is a morphogen?

Answer 24

-A Morphogen is a diffusible molecule that triggers different cell fates at different concentrations

Question 25

What happens to morphogen gradients within the embryo?

Answer 25

-Gradients need to be formed within the embryo and cell fate and changed accordingly

Question 26

What can morphogens provide?

Answer 26

-Can provide positional information within the embryo

Question 27

What genes confer positional identity and what do the drosophila antennapedia have instead?

Answer 27

Homeotic(eg Hox) genes confer positional identity:

-Drosophila Antennapedia mutants have legs instead of antennae

Question 28

What do homeotic genes regulate?

Answer 28

-Regulate the development of anatomical structures(identified in insects to control segment identity)

Question 29

LOOK AT EXAMPLE OF HOMEOTIC GENES IN NOTES

Answer 29

NOTES

Question 30

What does Turing’s reaction-diffusion model propose?

Answer 30

-This proposes a diffusible activator that activates a diffusible
inhibitor of itself

Question 31

What are Turing patterns?

Answer 31

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

Question 32

What are the steps to form a protein?

Answer 32

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

Question 33

What are changes in cell fate reflected by?

Answer 33

Changes in cell fate are reflected by changes in gene expression

Question 34

What secretions allow cells to communicate?

Answer 34

Secreted factors and other signals allow cells to communicate

Question 35

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

Answer 35

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