14. Drosophila development

Question 1

Describe Drosophila development? (5)

Answer 1

1) fertilisation
2) embryonic development
3) hatching
4) pupation
5) metamorphosis

Question 2

Why is drosophila a model organism for early development?

Answer 2

Segmentation of adult can be mapped to larval segments

Body plan determined by hierarchy of developmental
genes

Question 3

What two types of genes regulate segmentation pattern in drosophila? (2)

Answer 3

1) Maternal effect genes

2) Zygotic genes

Question 4

What do maternal effect genes do?

Answer 4

Phenotype of progeny is determined by maternal genotype

Question 5

What do zygotic genes do?

Answer 5

Phenotype of individual is determined by the individual’s genotype

1) Segmentation Genes - regulate segments of fly
2) Homeotic Genes - determines structures (wings, legs, etc…)

Question 6

What are the 4 functional classes of genes required for early development? (4)

Answer 6

• Egg-polarity genes
• Gap genes
• Pair-rule genes
• Segment polarity genes

Question 7

Describe the nomcluture in maternal effect genes?

Answer 7

A gene symbol in UPPERCASE normal indicates a wild-type allele
A gene in lower case, is the mutant allele

Question 8

Where is the anterior-posterior polarity determined?

Answer 8

The oocyte

Question 9

what are the 2 most important maternal effect genes? (2)

Answer 9

BICOID

NANOS

Question 10

Where are BICOID and NANOS located in oocyte?

Answer 10

BICOID mRNA located at anterior

NANOS mRNA located at posterior

Question 11

When does translation of BICOID and NANOS happen?

Answer 11

After fertilisation (only)

Question 12

How to BiICOID and NANOS produce opposing gradients in the early embryo?

Answer 12

By being tethered to they respective pole of the oocyte

Question 13

What is the relative concentration of BICOID and NANOS important for?

Answer 13

Regulating the zygotic genes

Question 14

What are the 3 categories of zygotic genes? (3)

Answer 14

GAP genes
Pair-rule genes
Segment Polarity genes

Question 15

What do zygotic genes do?

Answer 15

specify more and more restricted domains of the embryo

Question 16

What do homeotic genes do?

Answer 16

regulate the structures that develop on each segment of the adult fly

Question 17

Why were homeotic genes identified?

Answer 17

Homeotic Genes were identified because thereis atransformationof organs in which the developmental fate of an organ is changed to that of another (replacement)

Question 18

What are homeotic genes organised into?

Answer 18

Complexes

Question 19

What kind of transcription factors are homeotic genes?

Answer 19

homeodomain transcription factors

Question 20

What do homeodomain transcription factors do?

Answer 20

Regulate genes that specify tissue/organ primordia

Question 21

Are all homeobox contain genes homeotic genes?

Answer 21

No

Question 22

What are homeotic genes in humans and mice called?

Answer 22

Hox genes

Question 23

How many Hox clusters are there in mice and humans?

Answer 23

4 (A,B,C,D)

Question 24

What genes regulate human development?

Answer 24

Hox genes

Question 25

Where do mutations take place to cause large deletions? (2)

Answer 25

Mutations in ME(maternal effect) or major zygotic genes cause large deletions

Question 26

What do homeotic mutations result in?

Answer 26

Transformations

Question 27

How are homeotic genes for development of drosophila structures such as legs or wings arranged?

Answer 27

These genes are arranged in 2 clusters, collectively called the Hom-C cluster (antennapedia and biothorax)