lecture 2/3

Question 1

DEFINE: pattern development

Answer 1

the process by which cells are organised in space and time to produce a well-ordered structure within the embryo

Question 2

DEFINE: morphogenesis

Answer 2

cell and tissue movement + changes in cell behaviour that give the developing organ its shape in a 3D manner

Question 3

DEFINE: cell differentiation

Answer 3

process by which cells become different from each other and acquire specialised properties. governed by changes in gene expression which dictate the repertoire of protein synthesised

Question 4

DEFINE: specification

Answer 4

cells starting to restrict their potential as to what they will differentiate into and starting to engage into a certain lineage

Question 5

DEFINE: accretion

Answer 5

addition of extracellular matrix around the cell making the tissue larger

Question 6

How are developmental processes studied?

Answer 6

• embryology
• developmental biology
• animal models + use of genetics

Question 7

Funnel model

Answer 7

embryonic development amongst vertebrates is very similar during the early stage. diversity is present when the later stages are reached.

Question 8

Hourglass model

Answer 8

very early stages of embryonic development are not similar amongst vertebrates but intermediate stages are similar = correct model

Question 9

what is in situ hybridisation used for?

Answer 9

used to detect when and where mRNA is expressed in the cell

Question 10

describe the in situ hybridisation method

Answer 10

1. generate probe complementary to target mRNA sequence
2. label probe with DIG
   probe enters every cell and hybridises to its complementary mRNA
3. add an antibody specific to DIG
4. couple antibody with alkaline phosphate
5. alkaline phosphate hydrolyses phosphate -> results in a blue precipitate appearing where the transcript is present

Question 11

what are reporter lines used for?

Answer 11

to reveal where a gene is expressed in an embryo

could be used for lineage tracing

Question 12

describe the reporter line method

Answer 12

1. tag regulatory sequence of gene of interest with reporter gene sequence
   reporter gene = GFP, bGal etc.
2. introduce construct into animal model
3. transgene created which expresses GFP

Question 13

what are microarrays used for?

Answer 13

to compare expression profile of all genes present in the genome between 2 cell populations

Question 14

What is a disadvantage of microarrays used in developmental analysis?

Answer 14

cannot survey areas of an embryo because sufficient amounts of material need to be generated. young embryos have few cells.

Question 15

what is embryology?

Answer 15

observational biology
OR
tissue manipulation to test which tissues express gene of interest

Question 16

What is brainbow?

Answer 16

1. construct = many different genes coding for many different fluorophores
2. frame each gene with loxP sites
3. use homologous recombination to introduce construct into the embryo
4. under the control of a neuron-specific promoter, cre recombinase removes genes flanked by loxP sites. can excise none, one or two genes - choice made randomly in each cell
5. results in a wide range of colour combinations distinct in each of the cell types in which recombination has taken place during early embryonic development