0. Practical, Life cycle, Procedure

Question 1

Life cycle of Drosophila melanogaster

Answer 1

adult
embryo
1st instar larva
2nd instar larva
3rd instar larva
prepupa
pupa
adult

Question 2

Pattern formation

Answer 2

events that determine the spatial organization in the developing organism

Question 3

Syncytium

Answer 3

the early embryo of many insects consists of 1 large cell with many nuclei
• consists of syncronius nuclei that divide at the same time
• ONLY NUCLEI DIVIDE
• nuclei move to the border of the cell and a cell membrane forms between = many individual cells

Question 4

Syncytium v blastoderm

Answer 4

syncytium - 1 cell with many nuclei

blastoderm - cytoplasm divides to form many cells

Question 5

You can already draw a fate map from…

Answer 5

the blastoderm stage

• cells know what they’re to do

Question 6

Key events of embryogenesis occur in the

Answer 6

syncytial blastoderm stage
1. pole cell formation and migration
• pole cell = germline cells - pass on genetic info to next generation
2. determination of the anterior-posterior and dorso-ventral axes
3. segmentation = subdivision of the embryo along the anterior-posterior axis

Question 7

Egg cytoplasm

Answer 7

is not uniform

Question 8

Morphogens

Answer 8

chemicals in embryonic tissue that influence the movement and organization of cells

Question 9

Morhpogens form a

Answer 9

concentration gradient
• high concentration in anterior
• low concentration in posterior

Question 10

Bicoid

Answer 10

anterior to posterior gradient
• high concentration at the head
• low concentration at the tail

Question 11

Bicoid is required for

Answer 11

the formation of the head and thorax

Question 12

Bicoids with no anterior/posterior…

Answer 12

have 2 tails and no heads

Question 13

Wild type bicoids

Answer 13

high concentration in anterior

low concentration in the posterior

Question 14

High concentration in the middle

Answer 14

head in the middle

Question 15

Several morphogen gradients

Answer 15

determine the cell fates along the anterior-posterior axis

• cells read concentrations of morphogens

Question 16

Some animals have…

Answer 16

repeated units, including humans

Question 17

In Drosophila a segmentation gene cascade results in

Answer 17

the formation of segments

Question 18

Segmentation genes in Drosophila

Answer 18

morphogens to
gap genes to
pair-rule genes to
segment polarity genes

Question 19

To detect the expression of a protein…

Answer 19

use antibody staining

here segmentation proteins

Question 20

Transgenic

Answer 20

using wild type embryos +

additional bacterial genes

Question 21

Lab constructs

Answer 21

promoter (not expressed) +
bacterial gene (lacZ)
• all express lacZ - especially in 7 stripes

Question 22

In the embryo … is produced

Answer 22

the protein β-Galactosidase

• lacZ is the gene
• β-Galactosidase is the protein

Question 23

β-Galactosidase is expressed in

Answer 23

endogenous ftz gene

Question 24

2 step indirect antibody staining

Answer 24

1. primary antibody directed against β-Galactosidase
2. Incubate the secondary antibody to attache to the primary antibody
   • this reacts with the stain to turn blue

Question 25

4 steps (of embryos)

Answer 25

1. rehydrate
2. wash
3. block
4. antibody in primary antibody

Question 26

While rehydrating and washing the embryos…

Answer 26

be careful not to remove the embryos

Question 27

The Drosophila larva shows a complex pattern of

Answer 27

hairs and denticles

Question 28

Mutant larvae/embryos show

Answer 28

different shapes