Q6 - Developmental Genetics I

Question 1

What is the name of the structure in which oogenesis in Drosophila occurs?

What is this structure analogous to and why?

Answer 1

Ovariole

Looks like a string of beads as egg chambers are pushed down the structure, with each bead being progressively more developed

Question 2

What is the name of the region at the tip of the ovariole in Drosophila?

What occurs here?

Answer 2

Germarium

Start of oogenesis

Question 3

What is the progression of structures produced in the Drosophila germarium in terms of oogenesis?

Answer 3

Germ cell > cystoblast (1 mitosis) > cyst (4 mitosis, 1 oocyte and 15 nurse cells) > egg chamber (cyst surrounded by follicle cells)

Question 4

In Drosophila oogenesis, at what stages are there arrests in nuclear division?

Answer 4

Arrests in prophase I of meiosis in germarium
Arrests in metaphase I before ovulation
Continues at ovulation

Question 5

What happens to the structure and position of the oocyte in Drosophila as it travels down the ovariole?

Answer 5

It grows in size (nurse cells donate cytoplasm

Migrates to posterior

Question 6

In early Drosophila development, the oocyte cant produce mRNA. Where does this come from and how is it transported?

Answer 6

Transcribed from maternal genome in nurse cells
Enters oocyte through syncytial blastoderm
Transported in oocyte via polarised microtubules

Question 7

What does the maternal mRNA do within the zygote in Drosophila development?

Answer 7

Establish anterior-posterior polarity by activating or repressing certain zygotic genes

Question 8

What are the maternal mRNAs that have an effect on the zygote in early Drosophila development?

Answer 8

Bicoid - anterior

Nanos - posterior