Diff16 - 23

Question 1

When is the first light sensitive organ formed in drosophila?

Answer 1

Larval stage (not covered in this module)

Question 2

What is an imaginal disc?

Answer 2

Sac of diploid epithelial cells that proliferate through larval life, everting during pupariation to form adult fly structures

Question 3

What is meant by imaginal discs ‘everting’?

Answer 3

Concertina out into limbs

Question 4

What is responsible for loss of iris in mice and humans?

Answer 4

PAX6 loss

Question 5

What is interesting about PAX6?

Answer 5

Sufficient to make an eye, even interspecies

Question 6

How many ommatidia are in each drosophila eye?

Answer 6

800

Question 7

How many photo receptors (rhabdomeres) are in each ommatidia?

Answer 7

8

Question 8

What are the 8 photoreceptors in drosophila?

Answer 8

4 cones, 2 primary, 6 secondary, 3 tertiary pigment

Question 9

What other cells are associated with ommatidia?

Answer 9

Neuron, socket, sheath and bristle

Question 10

What is the supposed purpose of teriary pigment cells?

Answer 10

Optical insulation, preventing conduction of excitation across different ommatidia

Question 11

What are rhabdomeres?

Answer 11

Distinctive light sensitive structures

Question 12

Where is opsin in rhabdomeres?

Answer 12

On the millions of cilia

Question 13

What is interesting from one drosophila eye to the next?

Answer 13

Massively stereotypical; equator around line of notch activation - each hemisphere anti-parallel

Question 14

Why is it thought the two drosophila eye hemispheres are anti-parallel?

Answer 14

Brings together the two more concentrated sides of the arrangement, effectively increasing resolution

Question 15

Why can only 7 rhabdomeres ever been seen in section?

Answer 15

Middle one is half the height

Question 16

Where do R1-6 project?

Answer 16

Lamina

Question 17

Where do R7-8 project?

Answer 17

Medulla

Question 18

What optical feature evokes the greatest response from drosophila?

Answer 18

Movement

Question 19

What is the morphogenetic furrow?

Answer 19

Literal furrow in the surface of the eye that moves medially, controlling the wave of differentiation

Question 20

What occurs in the morphogenetic furrow?

Answer 20

Neurons and initial differentiation - undifferentiated cells stay basal

Question 21

How are ommatidia formed?

Answer 21

8 > 5 + 2 > 4 + 3 > 6 + 1

Question 22

How do R8 rhabdomeres space themselves?

Answer 22

Lateral inhibition by notch/delta

Question 23

Outline the cell cycle phases in the morphogenetic furrow

Answer 23

M in front, G1 in, S/G2/M after, then G1