History/Basic Concept & Drosophila development

Question 1

Specification State

Answer 1

Received instructions, but doesn’t have to follow, can still be influenced by the environment where it can change its fate if the environment changes (really more on potential than fate so it’s less committed)

Question 2

Determination State

Answer 2

Received instructions but can’t change fate has to follow instructions. It also can’t be influenced by environment so potential & fate are equal therefore its more committed

Question 3

Testing Specification

Answer 3

They removed a cell from its embryo (an eye cell) & grew it in a neutral media with no new stimulus, when they put the eye cell into a neutral media it was not specified if it didn’t receive signals to become an eye & express eye gene (blastula)

Question 4

When testing specification what resulted if the eye cell was specified?

Answer 4

If it was specified it received signal to become an eye & express eye gene (gastrula)

Question 5

Testing determination

Answer 5

They put an eye cell in a non-neutral environment so that it does have different stimulus & also challenge the cell in different environments

Question 6

What happened when testing the determination when the cell is not determined?

Answer 6

If the cell is not determined, then its influence by the environment where if you put an eye cell into muscle environment it becomes a muscle (gastrula)

Question 7

What happened when testing the determination when the cell is determined?

Answer 7

If the cell is determined, then it’s not influenced by the environment where if your put an eye cell (Or neurula) into a muscle environment it still stays as an eye cell

Question 8

Development Commitment

Answer 8

1. Specification (less committed) (blastula to gastrula)
2. Determination (more committed) (gastrula to neurula)
3. differentiation (neurula to embryo)

Question 9

Induction

Answer 9

Is cell to cell signaling, where one cell induces another

Question 10

What are the different inductive interactions??

Answer 10

1. Diffsuion
2. Direct Contact
3. Gap Junction

Question 11

Diffusion

Answer 11

An induction interaction where one cell has a receptor

Question 12

Direct Contact

Answer 12

An inductive interaction where both cells have receptors

Question 13

Gap Junction

Answer 13

An inductive interaction where both cells are connected together

Question 14

The inducer in an inductive interaction

Answer 14

Makes the signal in an inductive interaction

Question 15

The responder in an inductive interaction

Answer 15

In an inductive interaction the responder gets induced only if its competent (has a receptor or signaling pathway)

Question 16

How can a cell lose its competence over time?

Answer 16

By differential gene expression

Question 17

Morphogen

Answer 17

Molecule secreted by an inducer (specifies by concentration gradient & cells respond to different concentration)

Question 18

Asymmetrical division

Answer 18

Leads to cell differentation

Question 19

Fly development is similar to human development where it __________

Answer 19

Conserves Genes

Question 20

Describe a fly development

Answer 20

1. Develop inside eggs
2. Larva Hatch
3. Pupa
4. Metamorphosis to an adult

Question 21

Pole cells (common strategy to allocate germ cells early)

Answer 21

1. Posterior
2. Outside of blastoderm
3. Pole cell turn into gametes germ cells
4. Blastoderm turn into somatic cells

Question 22

Gastrulation

Answer 22

Occurs after cellularization & makes 3 germ layers

Question 23

What are the 3 germ layers that gastrulation makes?

Answer 23

1. Ectoderm (outside)- found in the cuticle & nervous system
2. Mesoderm (middle)- found in muscle, heart, & blood
3. Endoderm (Inside)- found in gut

Question 24

The germ layers is the ________

Answer 24

Unit of lineage

Question 25

Gastrulation is also the _________ in the ventral region

Answer 25

Invagination (Endoderm & mesoderm move inside & ectoderm cover the outside)

Question 26

Segmentation

Answer 26

Occurs after gastrulation

Question 27

Larva Hatches (24hpf) (For drosophila)

Answer 27

1. They grow without any wings or legs & have imaginal disk (primordial stem cells 2. Molts 2x & they become pupa

Question 28

Pupa goes through ___________ to become an adult

Answer 28

Metamorphosis (They change their form & the imaginal disk becomes organs)

Question 29

Nüsslein-Volhard + Wieschaus

Answer 29

Did a large-scale mutagenesis on drosophila & found out that random mutagenesis leads to random mutant

Question 30

What did Nüsslein-Volhard + Wieschaus find in their studies?

Answer 30

That the gap genes makes segments

Question 31

What is the axis of formation for syncytium?

Answer 31

1. A-P (Anterior -posterior) | 2. D-V (Dorso- Ventral)

Question 32

A-P axis

Answer 32

Has 3 regions

Question 33

D-V axis

Answer 33

Has 4 regions

Question 34

A-P & D-V axis

Answer 34

Organized simultaneously & have different mechanisms

Question 35

What are the maternal factors set up axes?

Answer 35

1. RNAs, proteins in the egg (occurs before fertilization & is predetermined) 2. Usually RTFs- regulate early development & activate zygotic genome 3. Zygotic genome- from a diploid nucleus & expressed after feralization

Question 36

What are the two classes of maternal genes for A-P axis for drosophila?

Answer 36

1. Bicoid anterior formation (mutant with no head) | 2. nanos posterior formation (mutant with no abdomen)

Question 37

________ is necessary for anterior structures

Answer 37

Bicoid 1. RTF 2. mRNA anterior of egg 3. Translation occurs after fertilization 4. A-P gradient increases the anterior 5. 1st morphogen gradient discover

Question 38

__________ expression of eye gene sufficient to make eyes elsewhere

Answer 38

Ectopic

Question 39

_______ is necessary for posterior structures

Answer 39

nanos 1. mRNA posterior of the egg 2. Translation occurs after fertilization (protein diffuses) 3. A-P gradient increases posterior 4. Not RTFs - works indirectly & translation of maternal hunchback mRNA in posterior

Question 40

Hunchback

Answer 40

1. Needed for anterior development & shouldn't be present in posterior 2. Nanos suppresses posterior hunchback translation (creates hunchback gradient) 3. Wont form anterior structures in posterior region

Question 41

Maternal genes for D-V axis

Answer 41

1. Dorsal protein- uniform distribution (cytoplasmic) 2. Toll receptor (inactive) - uniform distribution on the surface, gets activated in ventral 3. Toll receptor activated only in ventral 4. Dorsal enters ventral nuclei (gets D-V gradient)

Question 42

When toll is inactivated

Answer 42

Cactus keeps Dorsal in cytoplasm

Question 43

When toll is activated by ligand

Answer 43

1. it activates Cactus kinase (phosphorylates Cactus) 2. P-Cactus is degraded 3. Dorsal enters nucleus (turns on genes)