Part 3

Question 1

What is an equivalence group?

Answer 1

all cells have potential and ability to become same thing

Question 2

What is delta?

Answer 2

transmembrane ligand that activates notch

Question 3

What is notch?

Answer 3

a receptor, when bound to delta ligand it cleaves off t form aa fragment which forms part of a transcription factor complex

Question 4

how does feedback result in lateral inhibition in delta notch signalling?

Answer 4

negative feedback on the production of delta when notch is active o one cell expresses delta more strongly than the other and one expresses notch more strongly. The notch is the one expressing the inhibitory signal so that one become epidermis whereas delta becomes neutroblast

Question 5

What happens to the neuroblast ones differentiated?

Answer 5

it undergoes delamination, leaving the epidermal layer, then starts dividing asymmetrically so one cell formed is a basal cell and one a neural stem cell. Basal cell then becomes a ganglion mother cell that splits into a neurone or glia cell

Question 6

What is juxtocrine signalling?

Answer 6

cells have to be very close together, next to each other to signal

Question 7

phenotype if notch -/- and delta -/-

Answer 7

all become neurones

Question 8

4 cells making up the sensory bristle in fly?

Answer 8

sensory neurone, socket cell, sheath cell, hair cell

Question 9

What do sesonry organs arise from?

Answer 9

sensory organ precursor

Question 10

What is Numb?

Answer 10

a gene that inhibits notch signalling. What SOP divides into two one cell contains Numb and one doesn’t due to the numb only being localised in one half of the SOP cell

Question 11

If you over express notch or lose numb what do all the cells become ?

Answer 11

socket cells

Question 12

What is the growth cone?

Answer 12

at the tip of axons, use filopodia to direct growth of axon to guide to target. Fillopodia interact with other cells and the ECM. Influenced by cues = long distance - diffusible signals and short term - cell surface molecules

Question 13

What happens if you remove the lens of a newt?

Answer 13

Iris cells start to proliferate and start producing crystalline proteins to make lens again

Question 14

What happens if fuse human liver cells with rat muscle

Answer 14

liver cells silenced and become muscle cells as receive signals from rat cytoplasm

Question 15

Insert nuclei from kidney into the oocyte?

Answer 15

starts to express oocyte proteins as cytoplasmic factors control gene expression

Question 16

Insert gut nuclei into egg cell of xenopus?

Answer 16

albino gut cell into enucleated pigmented egg then starts dividing. Half of embryo cleaves so do serial nuclear transplantation and produces tadpoles that are all albino

Question 17

How was Dolly created?

Answer 17

nuclei from mammary tissue of white sheep inserted into black sheep egg.

Question 18

What can loss of Hh signalling cause?

Answer 18

midline malformation e.g. eyes fuse together is dominant mutation of Shh gene

Question 19

Cyclopamine in sheep?

Answer 19

eyes fuse in lamb as mother ate plant with steroidal hormone tetagon in it which interacts with smoothened

Question 20

How are smoothened and patches related to cancer

Answer 20

smoothened if mutated can become an oncogene

pathced is a tumour supressor gene so if mutated van cause cancer not stop it

Question 21

3 ways to treat type 1 diabetes?

Answer 21

1. transfect fibroblasts with transcription factor so pluripotent so become beta cells
2. somatic cell nuclear transfer egg then take cells from blastula stage and replant as embryonic stem cells
3. Give transcription factor from ectoderm tissue to reprogram cells.