Unit 1: Drosophila development

Question 1

How many segments of T and A make up drosophila ?

Answer 1

14 segments

Question 2

What is an oocyte ?

Answer 2

An immature egg that is produced in the ovaries

Question 3

What are maternal effect genes ?

Answer 3

• Genes that are expressed in the mothers ovaries
• The mRNAs are deposited into specific places in the egg and diffuse within the oocyte

Question 4

What 2 genes are deposited at the anterior ?

Answer 4

1) Bicoid
2) Hunchback

Question 5

What 2 genes are deposited at the posterior ?

Answer 5

1) Caudal
2) Nanos

Question 6

What happens in an absence of bicoid ?

Answer 6

The drosophila will have no head and will be all tail (No T1,2,3)

Question 7

What are the 4 drosophila zygotic segmentation genes ?

Answer 7

1) Gap genes
2) Pair rule genes
3) Segment polarity genes
4) Homeotic selector genes

Question 8

What is the function of a gap gene (4) ?

Answer 8

• Divides the embryo into 4 broad domains
• First genes that the drosophila embryo expresses themselves
• Encode transcription factors that are named after the phenotype
• Controlled by maternal effect genes

Question 9

What is the function of pair rule genes (4) ?

Answer 9

• Divides embryo into 14 subunits
• Encode transcription factors that are named after the phenotype
• Expressed in stripes (14 parasegments)
• Expression is controlled by gap proteins

Question 10

What is the function of segment polarity genes (2) ?

Answer 10

• Divides each subunit into anterior and posterior domains
• Expression controlled by pair rule proteins and then mutual repression

Question 11

What is the function of homeotic selector genes ?

Answer 11

They determine the fate of each segment

Question 12

What is a syncytial blastoderm (3) ?

Answer 12

• Early stage embryo
• No plasma membrane which allows easy diffusion around the embryo
• Start of zygotic segmentation genes

Question 13

What is cellularisation ?

Answer 13

• It is the process that separates the nuclei into individual cells
• Allows for signalling between cells for differentiation

Question 14

What is a segmentation gene ?

Answer 14

Gene that is responsible for dividing the embryo into groups to create gaps in the flys segmentation

Question 15

Where is Hedgehog (hh) expressed ?

Answer 15

Always anteriorly

Question 16

Where is Wingless (wg) expressed ?

Answer 16

Always posteriorly

Question 17

What is homeosis ?

Answer 17

The transformation of a whole segment or structure into a related one

Question 18

What is the homeotic complex (Hom-C) also known as ?

Answer 18

Hox genes

Question 19

What happens in an ultrabithorax mutant ?

Answer 19

• T3 is converted to T2
• Ubx is no longer expressed in T3
• Antp expression expands T2 into T3
• 2 Pairs of wings

Question 20

What happens in a proboscipedia mutant ?

Answer 20

• Labial laps transformed into T1 (legs)
• pb no longer expressed in labial palms
• Legs in place of mouth

Question 21

What is a maternal effect gene ?

Answer 21

One that causes a phenotype in her offspring

Question 22

Give an example of a maternal effect gene in drosophila

Answer 22

Bicoid

Question 23

What is a zygotic gene ?

Answer 23

One that is expressed in the zygote

Question 24

Give an example of a zygotic gene in drosophila

Answer 24

Hedgehog (hh)

Question 25

What is a morphogen (3) ?

Answer 25

• Proteins that are expressed at different concentrations in the embryo
• Tell cells what to do
• Conc in cells affects response

Question 26

Give an example of a morphogen in drosophila

Answer 26

Bicoid

Question 27

Give an example of a morphogenetic in a vertebrate

Answer 27

• shh
• Involved in limb development