L11 Drosophila as a developmental and genetic model

Question 1

Who established drosophilia as a genetic model organism?

Answer 1

Thomas hunt morgan

Question 2

What is saturation screening?

Answer 2

Saturation screening is a powerful genetic technique used to identify all the genes in an organism that, when mutated, can affect a particular biological process or phenotype.

Question 3

What is forward genetics?

Answer 3

Observe phenotype and work backward to identify the genes responsible for genotype

Question 3

What must the mutated genes need to be, to be able to show their phenotype?

Answer 3

Homozygous

Question 4

What is reverse genetics?

Answer 4

Reverse genetics begins with a known gene and then investigates its function by altering it and observing the resulting phenotype

Question 5

What did the mutant screens in drosophila lead to?

Answer 5

1. Basic understanding of how genes control elaboration of body plan.
2. Molecular identification of many new genes and cell - cell signalling pathways.
3. Confirmed “Genetics” as a extremely powerful way to dissect biological procceses.

Question 6

How long does it take for a fly to reach sexual maturity?

Answer 6

9 Days

Question 7

How long does drosphila live?

Answer 7

140 days

Question 8

What happens at 3 hours post fertilisation?

Answer 8

A cellular blastoderm would have formed so a single cell membrane is covering a yolk of nuclei

Question 9

What is micropyle?

Answer 9

Sperm entry point.

Question 10

Explain how a cellular blastoderm forms in Drosophilia embryos

Answer 10

• Fusion of sperm and egg nuclei
• Nuclear divison creating syncytium
• Nuclei migrate to periphery of cytoplasm
• Synctial blastoderm forms
• Cellular blastoderm forms

Question 11

At 3 hours post fertilisation what happens to the Dorosphilia embryo?

Answer 11

Embryo consists of a single layer of cells enclosing the yolk. At the posterior of the embryo, the pole cells are separated off: these will for the GERM LINE

Question 12

What happens during gastrulation?

Answer 12

• Three primary germ layers are established: Ectoderm, Mesoderm and Endoderm
• Also defines basic body plan, including anterior and posterior (head - tail), dorsal and ventral (back-belly)

Question 13

What are instars and what is the relevance with the fruit fly?

Answer 13

Instars = period between molting of organism

Fruit fly goes through 3 distinct instars