introduction

Question 1

can developmental biology continue in adult life?

Answer 1

yes, an example of this is neurogenesis in the brain

Question 2

what can be used to study different gene expression patterns?

Answer 2

DNA microarray heat maps

Question 3

what is the human connectome?

Answer 3

all of the connections in the human nervous system and how they vary between individuals

Question 4

what are the three body axis?

Answer 4

1. anterior/posterior
2. dorsal/ventral
3. left/right

Question 5

what was observed in Wnt7a knock out mice?

Answer 5

their claws were in the top of their hands as correct localisation signal was interfered with

Question 6

what are the three germ layers?

Answer 6

1. ectoderm
2. mesoderm
3. endoderm

Question 7

how can signals for a cell to differentiate be transmitted? (4)

Answer 7

• secreted
• pass through tiny nano-tubes from cell to cell
• cell bound
• gap junctions

Question 8

what is asymmetric stem cell division?

Answer 8

mitotic division producing two daughters of different cellular fates

Question 9

what is required for a cell to respond to a signal?

Answer 9

the correct receptor, looking for expression of this receptor can help model cell to cell interactions

Question 10

what are morphogens? (giving one example of where it is observed in nature)

Answer 10

a molecule with concentration dependent effects

butterflies develop spots through morphogen gradients

Question 11

what is the threshold concentration of a morphogen?

Answer 11

the concentration at which it triggers expression/repression

Question 12

Who stated the French flag hypothesis?

Answer 12

Lewis Wolpert, 1969

Question 13

what did the French flag hypothesis state?

Answer 13

different cells exposed to different concentrations of signal will have different gene expression and thus different cell fate

Question 14

describe a finding that challenged the classical role of morphogens

Answer 14

• drosophila engineered to express only tethered Wnt (wingless)
• Wnt could not diffuse
• this was predicted to impare wing development but this was not the case
  proposed that signal was spread through cell division

Question 15

what factors mediate embryo morphogenesis (shape change)? (5)

Answer 15

• cytokines
• signalling
• cell movement
• cell death
• space/tube formation

Question 16

give an example of how cell death aids morphogenesis

Answer 16

TGF-β is required for programmed cell death in interdigital webs of the developing mouse limb

Question 17

give an example of morphogenesis in the developing embryo

Answer 17

neural tube closure

neural plate fold in to form the tube. changes in cells actin cytoskeleton causes tube to constrict.

Question 18

what is spina bifida?

Answer 18

a neural tube defect where the spine does not develop properly leaving gaps in the spine, this is prone to infection.
caused by problems in Wnt signalling.

Question 19

what is neural tube convergent extension?

Answer 19

Planar cell polarity signal ensure that as the neural tube is closing, it is also lengthening with the embryo.
certain signals, for example Wnt, are required for this and if this doesn’t occur spina bifida develops

Question 20

give an example of how the scaling of an organism has been evolutionarily tweaked

Answer 20

crabs have scaled one claw to be larger than the other

Question 21

how can the expression of mRNA for observed in a developing embryo?

Answer 21

FISH, can be used to observe how the cycling of mRNA expression is slowed down in a more mature embryo

Question 22

what is a somite?

Answer 22

one of the paired segments along the neural tube of a vertebrate embryo, these are blocks of mesoderm

Question 23

name so additional factors that can influence an embryo in utero (4)

Answer 23

• exogenous factors (e.g. toxins)
• congenital defects (e.g. club foot)
• syndromes
• epigenetics

Question 24

give an example of how epigenetic inheritance can influence development

Answer 24

older fathers offspring tend to have a higher risk of developing autism (potentially epigenetic changes in older fathers sperm)

Question 25

certain cells are signalled to in early development as progenitors of gametes. what occurs next?

Answer 25

primordial germ cells migrate through the gut to developing gonads, here they divide less often and then undergo meiosis