LECTURE 2

Question 1

Homotoic mutant

Answer 1

when one cell type/tissue becomes another

Question 2

if no transcription factor present, what type of cell?

Answer 2

cell type 1

Question 3

if TF1 present, what cell type?

Answer 3

cell type 2

Question 4

if transcription factor 1 and transcription factor 2 present?

Answer 4

cell type 3

Question 5

if there is a TF1 mutant

Answer 5

cell type 1, cell type one, unsure as not seen in nature

Question 6

If there is a TF2 mutant

Answer 6

cell type one, cell type 2, cell type 2

Question 7

Function of inductive signals?

Answer 7

To have an impact on a cell by binding to receptors

Question 8

for TF1 to have an effect on a cell

Answer 8

medium dose of inductive signals

Question 9

for TF2 to have an affect on a cell

Answer 9

high dose of inductive signals

Question 10

signalling cell?

Answer 10

extracellular signal which causes a cell to follow a different fate

Question 11

why are xenopus good model organism

Answer 11

lots of embryos produced, embryos can develop externally, large embryo and therefore good grafting tissue of embryo, tissue heals well

Question 12

Dorsal lip

Answer 12

where cell movements first occur

Question 13

what did Hans speman do and discover

Answer 13

He took his daughters hair and tied it found a xenopus embryo to isolate the nucleus to one side, allowed blastula to form. Formed two embryos. One which was ‘normal’ and one ‘belly piece’.

His other experiment involved isolating the grey crescent to one side of the embryo, and again had a great effect on the body plan of the xenopus.

Question 14

what happens if you remove the dorsal lip from one embryo and place it into a host so it has two dorsal lips? Conclusion from this experiment?

Answer 14

two headed conjoined embryo. Dorsal lip responsible for head development

Question 15

Define cell fate?

Answer 15

what the cell will become in the future.

Question 16

signal transduction?

Answer 16

relays the signal from the extracellular signal to the nucleus where it activates a gene

Question 17

how can we experiment the effect of expression of a particular gene on an embryo?

Answer 17

modify a vector to have a gene of interest, inject mRNA into embryo.

Question 18

UV effect on an embryo

Answer 18

can inhibit grey crescent formation (stopping the cortical cytoplasm rotating). But only if exposed at the vegetive pole.

Question 19

Noggin has an effect on the embryo in what sense?

Answer 19

it’s concentration.

Question 20

if gene for noggin is injected (stable transfection)

Answer 20

high concentration of noggin produced and therefore forming a bellypiece.

Question 21

if mRNA for noggin injected

Answer 21

a small concentration of noggin is present in the cell and therefore allows for normal development

Question 22

Noggin is ?

Answer 22

A signalling molecule

Question 23

purpose of in situ-hybridiaiton

Answer 23

to see the location of gene expression

Question 24

Purpose of an RNA probe attached to a tag in in situ-hybridisation?

Answer 24

Its complementary to mRNA

Question 25

What are antibodies labelled with in in situ-hybirdisation

Answer 25

enzymes which recognise the tag

Question 26

Addition of substrate (in situ-hybridisation)

Answer 26

enzyme catalyses the decomposition of the substrate producing a coloured precipitate

Question 27

spemaan organisier

Answer 27

provides inductive signals in mammals, cells found closer to this signalling centre will adapt dorsal traits.- CELL TYPE 3