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Mechanisms of development Flashcards

1
Q

What is genomic equivalence?

A

The genome is identical in every cell

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2
Q

What is differential gene expression?

A

Genes are expressed differently due to different transcription factors

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3
Q

What are the major differences between animal and plant development?

A

Plant:
- Body develops in embryonal and post embryonal stage
- the development of the body is highly reactive to environmental factors
- cells have a rigid cell wall and do not move

Animal:
- body is almost fully ready in embryo
- the development of the body is less affected by the environment
- cells change position in the body to form layer

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4
Q

Why is Arabidopsis thaliana a good model plant?

A

Out of all plants the most is known about the Arabidopsis Thaliana. (arabidopsis.org) They have a short genomen and a quick life cycle. The entire genome is sequenced and it has powerful reverse and forward genetics

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5
Q

How is the plant hormone auxine transported?

A

In a polar manner

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6
Q

How does PIN auxin transport proteins control where primordia are formed
in meristems?

A

PIN proteins or auxin efflux carriers are located on one side of the cell and can pump auxin. Hereby they determine the concentration of auxin.

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7
Q

How do gradients of PLETHORA (PLT) transcription factors control
pattern formation in arabidopsis roots?

A

PLETHORA gene transcription is triggered by auxin concentration.
The PLT protein is then spread across the daughter cells and forms a gradient. This gradient can be read and causes pattern formation.

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8
Q

When are CEP proteins induced?

A

They are induced in the roots that receive low levels of N.

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9
Q

When are CLE proteins induced?

A

They are induced in the roots that receive high levels of N.

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10
Q

What perceives CEP and CLE signals and what happens as a result?

A

They are perceived by shoot expressed receptors and as a result mobile miRNA’s are expressed.

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11
Q

What is RNA in situ hybridisation?

A

Single strand RNA can hybridise with the complementary strand easily. If the complementary strand is added the RNA will hybridise to messenger RNA. A label is added to the complementary strand so that the location of the desired gene can be studied.

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12
Q

What is the life cycle of drosophila?

A

Adult -> fertilized egg -> cleavage -> sinsitial blastoderm -> gastrulation -> embryo -> hatching -> 1st instar larva -> 2nd instar larva -> 3rd instar larva -> pupa -> metamorhposis -> adult

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13
Q

What is the body plan of drosophila?

A

Head - thorax - abdomen

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14
Q

What are the the four categories of genes that control subsequent steps of drosophila embryo development? And how do they influence each other?

A
  • maternal effect genes/egg polarity genes
  • gap genes ( activated by egg polarity genes)
  • pair rule genes (controlled by gap genes)
  • segmentation genes & hox genes
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15
Q

What is a morphogen?

A

A morphogen is a gene that has at least 3 different read outs based on its concentration.
They are diffusable proteins or other molecules

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16
Q

What initiates the formation of the anterior-posterior (A-P) axis of drosophila embryos?

A

a gradient of the transcriptional regulator BICOID

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17
Q

What initiates pattern formation along the dorsal-ventral (D-V) axis of drosophila embryos?

A

a gradient of the transcriptional regulator DORSAL

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18
Q

What are maternal effect genes?

A

Genes that are active during egg cell formation before fertilization.
They are necessary for embryogenesis.
BICOID NANOS CAUDAL AND DORSAL are maternal effect genes

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19
Q

What three groups of segmentation genes pattern the AP axis?

A

BICOID and HUNCHBACK for the anterior side, CAUDAL for the anterior side

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20
Q

What is a fate map?

A

It is a map of all different kinds of cells in an organism, they are made by giving a label to a living cell so it can be tracked to see how they contribute to a living organism.

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21
Q

What is BICOID?

A

A kind of morphogen responsible for the formation of a gradient in early stages of the egg cell formation.

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22
Q

Where is BICOID mRNA located?

A

The posterior side

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23
Q

Where is nanos mRNA located?

A

On the anterior side

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24
Q

Where is caudal mRNA located?

A

Everywhere

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25
Where is hunchback mRNA located?
everywhere
26
What is the generation time of the drosophilia?
9-10 days
27
What is a syncytium?
A cell with multiple nuclei
28
What happens to the nuclei in the syncytium that forms during as a part of the development of the drosophilia?
The nuclei start randomly distributed across the syncytium after which they move to the periphery and cell boundaries start to form. There is no longer a syncytium.
29
What does APT stand for?
Anterior posterior terminal
30
Do homozygote mutant in maternal effect gene (for example a mutant that has no BICOID) females produce offspring?
No, they are viable but produce no offpring. Genetics keep mutation by selecting heterozygotes.
31
Can heterozygote mutant females produce offspring?
The mutant can produce 1/4th viable male offspring, but no female offpsring if crossed with a heterozygote male.
32
What does the embryogenesis of drosophilia start with?
A syncytium
33
What role does segmentation play in embryogenesis of drosophilia?
It fully defines all segments of the body
34
How does nanos affect Hunchback protein translation? Does this happen on the anterial or posterial side?
Nanos inhibites Hunchback protein translation, this happens at the anterial side
35
How does BICOID affect caudal protein translation? Does this happen on the anterial or posterial side?
BICOID inhibits caudal protein translation, this happens at the posterial side
36
What are examples of gap genes?
Hunchback krüppel knirps giant tailles huckebein buttonhead empty spiracles orthodenticle
37
What do gap genes do?
Define large areas of the development
38
What do pair rule genes do?
Define the larger areas into smaller areas
39
What do segmentation polarity genes do?
Fully define all segments
40
How does BICOID regulate the Hunchback expression?
Until a certain low threshold BICOID stimulates Hunchback translation. At the posterior side there is also Hunchback translation, but this cannot be due to BICOID because it is not present there. It is unknown what causes this Hunchback translation
41
What does Hunchback determine in the development of the embryo?
The position of the headfold
42
How does Hunchback influence krüppel?
In high concentrations it can bind to the promoter of krüppel and represses it In low concentration it stops the inhibition and activates krüppel The affinity for the activator is higher, in lower concentrations it stays bound at the activation site and not the repression site. The repressor is however dominant over the activator, when both are bound only repression happens.
43
What are pair rule genes?
Decide segment boundaries, pair rule gene mutants miss every other segment
44
What is the characteristic expression pattern of pair rule genes and how is this pattern formed?
The characteristic expression pattern of pair rule genes is striped. this is formed before cells are. EVE defines odd numbered parasegments, ftz defines even numbered parasegments. Anterior expression margin defines anterior boundary of the parasegment.
45
Which proteins control the expression of pair-rule genes, and how do they act as repressors or inducers?
BICOID and HUNCHBACK activate EVE in a broad domain, sharp borders of EVE are determined by GIANT and KRÜPPEL. These are examples of transcription factors. BICOID and HUNCHBACK are inducers, GIANT and KRÜPPEL are repressors
46
How are the drosophila segment polarity genes activated by combinations of pair-rule gene proteins?
Pair rule gene proteins determine the boundaries of different segments. They act as transcription factos for the translation of polarity genes either inhibiting or inducing translation of the polarity genes.
47
What is the role of the diffusable signalling proteins WINGLESS and HEDGEHOG in segment polarization?
Feedback between between WINGLESS and HEDGEHOG secreting cells stabilize borders between parasegments.
48
What are the WINGLESS and HEDGEHOG signal transduction pathways and how do they stabilize parasegment boundaries?
Wingless/B-catenin signalling pathway o Armandillo (B-catenin) is a transcriptional co-factor that in absence of Wingless signalling is degraded. o When Wingless binds to its receptor Frizzled degradation of Armandillo is inhibited. o Armandillo moves into the nucleus and activate target genes of Wingless signalling, among which is engrailed. o Engrailed can active itself (autoactivation), and hedgehog. Hedgehog signalling * Hedgehog peptide is secreted a perceived by the Patched receptor in neighbouring cells. * The activated pathway results in expression of wingless. o Hedgehog signalling induces its own receptor and Wingless signal production in neighbouring cells. o Engrailed reduces Wg receptor (Frizzled) expression, which destabilizes Wg and prevents its excessive posterior movement. o Engrailed auto-activates itself and inhibits Hedgehog receptor (Patched) production.
49
What is a kinase?
A protein with an activity than can phosphorylate other molecules
50
What is Cell-lineage restriction?
cells and their descendants in one parasegment never move to adjacent parasegments. This results in isolated compartments, which contain only descendants of cells of a single parasegment
51
What does the protein DORSAL do and where is it located?
It is located in the ventral nuclei. DORSAL induces other transcription factors. These promote specific cell fates in collaboration with A/P transcription factors.
52
What is proliferation?
The dividing of cells into multiple cells
53
How do cells specialize?
differential gene expression
54
What is an important part of cel-cel interaction?
Cells influencing nearby cells as inducers or inhibitors
55
What happens during cleavage?
The initial epithelial layers are formed. The multicellularity of the single cell is established.
56
What happens during gastrulation?
Formation of 3 germinal layers: ectoderm, mesoderm and endoderm Creation of the archenteron
57
What happens during neurolation?
Formation of neural tube and neural crest
58
What are the different forms of gastrulation?
Different ways for cells to move inwards of the embryo; Invagination, involution, ingression, delamination and epiboly.
59
What happens during cortical rotation?
The outside of the eggcel rotates after the sperm cell enters. This is caused by the relocation of Wnt11 mRNA. WNT is usually located at the vegT, but this is no longer the case after rotation. The end position of WNT and vegT determine where the dorsal side will be, at the WNT side.
60
What forms from ectoderm?
- Epidermal layer of skin - neural crest - central nervous system
61
What forms from mesoderm?
- dorsal notochord - paraxial bone tissue - intermediate tubule cell of the kidney - lateral red blood cells - head facial muscles
62
What forms from entoderm?
- digestive tube stomach cell - pharynx thyroid cell - respiratory tube lung cell
63
What is PCP (planar cell polarity) pathway? for non canonical wnt signalling
Pathway through which cells become polarised, it is non canonical because it does not involve β-catenin
64
What is canonical wnt signalling?
WNT signallng causes accumulation of β-catenin in xenopus embryo during its development
65
What role does ephrin have in the formation of the neural crest?
Neural crest cells recognise eprhin and will not go to regions rich in ephrin, the ephrin leads the neural crest cells to their proper position
66
What is contact inhibition of locomotion?
If the neural crest cells come in contact with other neural crest cells they change direction. The contact between neural crest cells inhibit their locomotion. Neural crest cells do not wish to be near eachother.
67
What role do placode cells play in the localisation of neural crest cells?
They produce stromal derived factor 1 (SDF1), neural crest cells have a receptor for this called CXCR4. If SDF1 is sensed the neural crest cells start to chase this and in the process push the placode cells forward. The placode cells move away from the neural crest cells, this is called the run.
68
What are all parts necessary for neural crest cell migration?
- EMT - contact inhibition - chemorepellent (guidance) - chemoattractant (chase)
69
what is modular repetition?
70
what are homeotic selector genes?
71
What is the drosophila antennepedia mutant and what kind of mutation is this?
Antennapedia (Antp) is a Drosophila Hox gene, which controls the formation of legs. Loss-of-function mutations in the regulatory region of Antp result in the development of the second leg pair into ectopic antennae. Gain-of-function alleles convert antennae into ectopic legs !
72
what mutation causes two pairs of wings in drosophila?
A mutant with Ubx hox gene expression blocked only in P5 will have a second set of wings instead of halters.
73
How did vertebrate HOX genes possibly evolve from Cnidarian HOX genes?
74
what are the homeotic selector genes in plants?
75
how is flower development regulated?
76

Biology (5 decks)

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