lecture 3

Question 1

What is different about gastrulation in drosophila and in Xenopus?

Answer 1

SUPERFICIAL-CLEAVAGE. Nucleic divide but membrane doesn’t form around in one until later on.

Question 2

Posterior end of egg?

Answer 2

Form pole cells, to form gametes

Question 3

Syncytial blastoderm?

Answer 3

when nucleic move to the outer edges of egg

Question 4

Cellular blastoderm

Answer 4

when membranes form around the nuclei

Question 5

When does the cynical blastoderm form

Answer 5

after the 9th division

Question 6

Cephalic fold?

Answer 6

Head region anterior

Question 7

Ventral furrow is where what occurs

Answer 7

Invagination occurs

Question 8

Tube will extend?

Answer 8

The entire length of the embryo beneath the ventral furrow

Question 9

What happens at the same time as gastrulation

Answer 9

germ band extension

Question 10

What cell layer hasn’t formed after gastrulation?

Answer 10

Endoderm

Question 11

Tube like structure will eventually form which cells

Answer 11

mesoderm

Question 12

How is the third layer formed

Answer 12

movement of ventral tissue around the posters end and onto the ventral side. Cells invaginate into the embryo and fuse to form the gut.

Question 13

joining of the primitive gut will eventually form?

Answer 13

Nervous system

Question 14

If neuralation does occur

Answer 14

vertebrates

Question 15

Segmentation?

Answer 15

Body segments form

Question 16

Does neurulation occur in drosophillia ?

Answer 16

No, as they are not vertebrates

Question 17

Halteres

Answer 17

balancing organs

Question 18

genetic screen

Answer 18

a technique used to identify and study an interesting phenotype within a mutated population

Question 19

Forward genetics ?

Answer 19

1-Generate the mutant
2- identify the genes which are mutated
3- find where the gene is expressed

Question 20

Why are Drosophilla well suited to genetic screens, and examples of two other organisms which are too?

Answer 20

• quick gestation Time
• simple genome (4 chromosomes 13,000 genes)
• small and cheap to maintain
• easy to see the phenotype

zebra fish and yeast

Question 21

Homeotic mutation

Answer 21

one which converts one structure into another.

Question 22

discovery of homeotic mutants was when

Answer 22

1970’s/80’s

Question 23

Homeotic genes which control

• head region
• thorax
• abdomen

Answer 23

• LAB
• Dfd
• SEX combs reduced (SCR)
• antennaoedia (antp)
• ultrabithorax (ubx)
• abdominal b (AbdB)
• abdominal a (abdA)

Question 24

Homeotic genes within fruit fly

Answer 24

found near to eachother in the genome- IN SITU HYBRIDISATION
- the same order in which the genes appear on the chromosome, as they are expressed as mRNA in drosophila( BODY PLAN)

Question 25

Collinearity

Answer 25

order in which they are found in the chromosome, are expressed in the body plan

Question 26

Nobel Prize for this work on collinearity in drosophila

Answer 26

1995, Eric and Christiane

Question 27

Homeobox transcription factors?

Answer 27

Activate genes which specify organ and cell types

Question 28

which homeobox genes give rise to anterior?

Answer 28

lab and Dfd

Question 29

Thoracic segment 1 homeobox gene

Answer 29

Scr

Question 30

Thoracic segment 2 homebox gene

Answer 30

Antp

Question 31

Thoracic segment 3 Hox genes

Answer 31

ubx Antp

Question 32

Abdominal segment hox genes

Answer 32

AbdA and B and UBx

Question 33

Scr gives rise to

Answer 33

pair of legs

Question 34

Antp gives rise to

Answer 34

pair of legs and wings

Question 35

Ubx and antp give rise to?

Answer 35

Pair of legs and halteres

Question 36

Ubx mutant gives mutation gives rise to ?

Answer 36

Two pairs wings (loss of function of Ubx gene)

Question 37

Antp mutation?

Answer 37

Legs out of head, gain of function

Question 38

How many hox genes in mammals?

Answer 38

38