gene expression in development

Question 1

what are the two stages of commitment in gene expression?

Answer 1

1. specification

2. determination

Question 2

what happens in the first stage of commitment and is it reversible/irreversible?

Answer 2

SPECIFICATION: these cells are capable of differentiating autonomously if placed in isolation but can be respecified if exposed to certain chemicals/signals. It is REVERSIBLE.

Question 3

what happens in the second stage of commitment and is it reversible/irreversible?

Answer 3

DETERMINATION: cells will differentiate autonomously even the exposed to other factors or placed in a different part of the embryo. IRREVERSIBLE

Question 4

what is the cell fate?

Answer 4

the fate of the cell describes what it will become in the course of normal development

Question 5

does the fate of determined cells change?

Answer 5

no

Question 6

what are the FOUR stages the cell goes through during development?

Answer 6

Naive
specified
determined
differentiated

Question 7

what is competence of a cell

Answer 7

the ability to respond to chemical stimuli

Question 8

what type if potency are cells of the inner mass cells of the blastocyst?

Answer 8

pluripotent (i.e. they can divide to give rise to all different types of cells of the embryo but not the trophectoderm cells which form the placenta

Question 9

what type of potency are hamatopoetic cell?

Answer 9

multipotent

Question 10

what is bivalent chromatin?

Answer 10

methylated chromatin which has both on and off signals - hasn’t decided if it is going to be expressed yet

Question 11

what is the definition of potency?

Answer 11

the entire repertoire of cell types a particular cell can give rise to in all possible environments

Question 12

what are the two different ways a cell receives signals to become specified?

Answer 12

• intrinsic signal (cell autonomous signal tells the cell where it is)
• extrinsic signal (signal from the environment gives the cell spatial information about where it is)