Developmental committment

Question 1

Committed vs not committed

Answer 1

• see figure

Question 2

How do cells become committed to form a tissue?

Answer 2

• through the process of differentiation

Question 3

cell fate

Answer 3

• what a cell or tissue develop into
• early committed cell is not phynotypically different from uncommitted cell
• normal fate does not mean cell develops the same in every environment

Question 4

potency

Answer 4

• potential to differentiate

Question 5

commitment

Answer 5

• state in which a cells developmental fate becomes restricted
• not displaying big changes in biochemistry or function

Question 6

specification

Answer 6

• group of cells gain a bias toward certain cell fate
• if isolated and cultured, develop according to that fate
• flexible process, can still be altered due to signals

Question 7

determination

Answer 7

• cell fate irreversible
• stable change in internal state of a cell, fate is now fixed
• CANNOT develop into another type in response to signals

Question 8

developmental stages

Answer 8

• see figure

Question 9

acquisition of committment

Answer 9

• cells receive signals that cause them to develop down a certain pathway… asymmetrical signals determine fate
• internal signals
• external signals
• see figure

Question 10

induction

Answer 10

• instructive signals from one cell or tissue
• cause change in cellular behavior of responding cells

Question 11

competence

Answer 11

• cells in presence of the signal must be competent to respond for a change to occur

Question 12

Draw normal vs lack of induction/competence

Answer 12

–

Question 13

how are cells differentially induced

Answer 13

• morphogen gradient
• lateral inhibition

Question 14

morphogen gradients

Answer 14

• cells respond to signals in a concentration-dependent manner
• concentrations of activin leads to different types of mesodermal cells…
• see figure

Question 15

use of morphagens to give positional information

Answer 15

• see graph

Question 16

induction

Answer 16

• one cell produces a molecule that causes adjacent cells to differentiate with a specific fate

Question 17

morphogens

Answer 17

• form concentration gradient to determine fate of cell

Question 18

general lessons of morphogen gradients

Answer 18

• 1) morphogen concentration dependent induction of gene expression
• 2) both activators and repressors determine expression patterns
• 3) combinatorial gene control mechanisms
• 4) regulatory gene hierarchy

Question 19

morphagen concentration dependent induction of gene expression

Answer 19

• ## see figure

Question 20

both activators and repressors determine expression patterns

Answer 20

• ## figure

Question 21

combinatorial gene control mechanisms

Answer 21

• combo gene control occurs when gene expression requires presence or absence of particular combo of regulatory proteins
• TF’s used in different combos to regulate
• creates complex networks
• see figure

Question 22

regulatory gene hierarchy

Answer 22

• see figure

Question 23

early gradients activate gap genes

Answer 23

• cascade begins when signals from maternal proteins activate gap genes…
• each gap gene is expressed in specific domain in embryo
• further refined through pair rule genes

Question 24

what controls composition and function of the positional info that patterns embryos?

Answer 24

• combinatorial interactions
• negative feedback

Question 25

central idea to differentiation of tissues and organization?

Answer 25

• morphogen concept
• diffusible signaling molecules are proposed to coordinate cell fate specification and tissue formation using concentration dependent mechanisms

Question 26

Morphogen gradiants

Answer 26

• not static
• change with time.,.. time is a critical parameter

Question 27

lateral inhibition

Answer 27

• one cell produces an inhibitor that prevents neighboring cells from differentiating with a particular fate
  ex: drosophila cells express brown, become ectoderm, inhibit neighboring cells from doing the same thing

Question 28

lateral inhibition in the determination of cell fate

Answer 28

• cell starts off as equivalent
• stochastic event causes one cell to produce more of a singla molecule at some critical time
• difference is amplified until cell becomes different types

Question 29

lateral inhibition in patterning

Answer 29

• gibing tissues a cell spacing pattern (figure)
  ex: neurons and glial cells