stem cells and lineage

Question 1

how do you go from a single cell to an organism

Answer 1

control in space and time

Question 2

what is differentiation

Answer 2

process by which a cell undergoes a change to an overtly specialised cell type

Question 3

what is specification

Answer 3

if you can isolate cells or tissues and they still form what they were originally meant to then their fate was already specified

Question 4

what is induction

Answer 4

process by which one embryonic region interacts with a second region to influence that second regions differentiation or behaviour

Question 5

where do induction signals come from

Answer 5

other cells or the environment

Question 6

what are three cell signalling mechanisms

Answer 6

dissusion
direct contact
gap junctions

Question 7

what is an example of induction

Answer 7

vegetal tissue induces mesoderm in animal cap

Question 8

what is determination

Answer 8

progressive restriction in developmental potential of different cell types

Question 9

what is competence

Answer 9

cells may be competent to receive signals only for a short time

Question 10

what is regulative development

Answer 10

also called indeterminate

is remaining cells can compensate for tissue loss

Question 11

what is mosaic development

Answer 11

also called determinate

seperation of blastomeres results in incomplete parts of embryos in development is usually arrested

Question 12

what are three ways that different lineages can arise from a common cell ancetsor

Answer 12

asymmetric inheritance
asymmetric cell division
timing and position are important

Question 13

what are 3 ways of asymmetric inheritance and name one exmaple

Answer 13

protein or rna
uneven distribution
inherent difference
the germ line

Question 14

why is timing so important for the arison of new lineage

Answer 14

early stages my be regulative but lineages can then become determines and invariatn

Question 15

describe long and short range signals pattern tissue

Answer 15

all multicellular organisms use the same pathways

Question 16

what are morphogens

Answer 16

exposure time or concentration differences caused by diffusion of inducer (morphogen) away from the source

Question 17

why is half life of morphogens important

Answer 17

protein degredation can be increased

as is the rate of diffusion- ECM can slow morphogens down

Question 18

what do morphogen gradients equal

Answer 18

differentiation differences

Question 19

what is lateral inhibition

Answer 19

can go on to act as signalling centers for further patterning

Question 20

describe notch signalling

Answer 20

transient asymmetry is enough

Question 21

describe positive feedback for notch signalling

Answer 21

asymmetry is self amplifying

Question 22

give an example of notch signalling

Answer 22

at first, contiguous neural plate cells express neurogin delta and notch
with time one cell expresses more delta, develops into a neuroblast and inhibits the neighbouring cells from following a neural fate

Question 23

what are two examples of how the same signal can induce different responses

Answer 23

combinatorial signalling

cell memory