Morphogens

Question 1

What is the role of maternal mRNA during oogenesis in Drosophila?

Answer 1

Developing eggs are provisioned with maternal mRNA

Question 2

When do zygotes typically commence transcription after fertilization?

Answer 2

After 2-3 divisions

Question 3

What is the function of Bicoid (Bcd) in Drosophila?

Answer 3

Establishing the A-P axis

Question 4

What does Bicoid (Bcd) protein serve as a morphogen for?

Answer 4

Head and thorax development

Question 5

Define morphogen.

Answer 5

Compound with a non-uniform distribution establishing positions of specialized cell types and tissues

Question 6

What occurs when Bicoid-containing cells are transplanted?

Answer 6

Induces ectopic anterior identity

Question 7

What is Spätzle a morphogen for?

Answer 7

Dorso-ventral axis formation

Question 8

What prompts the translocation of Dorsal to the nucleus?

Answer 8

Phosphorylation of Dorsal at the ventral region

Question 9

What are some target genes regulated by Dorsal?

Answer 9

• Decapentaplegic (DPP) * Sog * Snail

Question 10

Morphogens induce a signaling cascade that controls what?

Answer 10

Pattern formation

Question 11

What is the significance of where a gene is expressed?

Answer 11

It can have a major impact on the body plan

Question 12

What are Hox genes responsible for?

Answer 12

Specifying segment position and identity

Question 13

What are homeotic genes?

Answer 13

Genes responsible for homeosis

Question 14

What do homeotic genes contain that is crucial for their function?

Answer 14

A homeodomain (homeobox)

Question 15

What is the concept of homeosis?

Answer 15

Transformation from one body part to another

Question 16

What is temporal collinearity?

Answer 16

Genes are temporally transcribed in sequence

Question 17

What evolutionary event leads to the diversification of Hox genes?

Answer 17

Gene duplication

Question 18

What is the difference between orthologs and paralogs?

Answer 18

• Ortholog: evolved from a common ancestral gene * Paralog: copies of a gene within the genome

Question 19

What determines the anterior limb position in vertebrates?

Answer 19

Anterior position of Hoxc6 expression boundary

Question 20

What is the role of Sonic hedgehog (SHH) in limb development?

Answer 20

Morphogen of A-P axis in limb

Question 21

What is the significance of the ZPA regulatory sequence (ZRS)?

Answer 21

Enhancer of Sonic hedgehog activity in Zone of Polar Activity (ZPA)

Question 22

What is the evolutionary impact of Hox genes on body plans?

Answer 22

Diversification of body plans through segmentation

Question 23

What adaptation is seen in humans regarding cervical vertebrae?

Answer 23

All mammals have seven cervical vertebrae

Question 24

What is the average number of sacral vertebrae in humans?

Answer 24

5.2

Question 25

How do extra cervical vertebrae in embryos relate to congenital conditions?

Answer 25

Associated with congenital cancer

Question 26

What do Hox genes regulate besides body parts?

Answer 26

Stem cell proliferation

Question 27

Fill in the blank: The __________ of limb development involves the re-establishment of A-P and D-V axes.

Answer 27

Basic principles

Question 28

True or False: The genetic toolbox for development is evolutionary extremely conserved.

Answer 28

True

Question 29

What is the hourglass model used to explain?

Answer 29

Morphological diversity in developmental stages

Question 30

What are the two types of homology in duplicated genes?

Answer 30

* Ortholog * Paralog