Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pattern Formation > Morphogen Gradient & Tissue Patterning > Flashcards

Morphogen Gradient & Tissue Patterning Flashcards

1
Q

What are spatial instabilities, and how do they occur?

A

Spatial instabilities occur when a system exhibits heterogeneous behaviour across space, leading to the formation of distinct patterns or structures in a spatial domain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are temporal instabilities, and how do they occur?

A

Temporal instabilities refer to fluctuations or oscillations over time rather than space. These can manifest as periodic or chaotic behavior in a system’s dynamics.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do spatial vs temporal instabilities come about?

A

Spatial instabilities = local positive feedback and long range inhibition

Temporal instabilities = local positive feedback and negative feedback with a delay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Explain the difference between self-organized vs programmed development

A

Self-organized development means complexity emerges from local interactions

Programmed development means existence of a plan, complexity is embedded beforehand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Give and example of self-organized development

A

Zebrafish embryo

Self-organized segmentation = multi-scale integration to form the clock((synchronization) and wavefront

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give an example of programmed development

A

Drosophila embryo

Programmed segmentation = hierarchical biochemical sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What model does Wnt-DKK/BMP depict?

A

Reaction-diffusion model based on simple chemical diffusion

Wnt is the short ranged autoactivator and activates DKK/BMP
DKK/BMP is the long-range inhibitor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens when DKK is overexpressed?

A

WNT and its inhibitor DKK as primary determinants of murine hair follicle spacing, using a combined experimental and computational modeling approach.

Transgenic DKK overexpression reduces overall appendage density.

Moderate suppression of endogenous WNT signaling forces follicles to form clusters during an otherwise normal morphogenetic program

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What model is Notch-Delta based on?

A

Reaction-diffusion model based on CELL-CELL CONTACT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What describes RD models based on cell movement?

A

RD wave on the skin of marine angelfish

Two different coloured cells (melanophores) when partially ablated will react and regenerate based on self-orgnaization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

If the RD model is not limited to molecules, what else can it be applied to?

A

Cell motion
Mechanical forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In Turing patterns how is symmetry broken?

A

Through feedback and self-roganization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens if there is asymmetry in the system to begin with?***

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define positional information

A

In developmental biology, refers to the concept that cells in a developing organism can interpret their location within a spatial coordinate system and adjust their behaviour accordingly.

This process is crucial for the proper organization and differentiation of cells during embryonic development.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Francis Cricks model for positional information?

A

Source and sink model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the French Flag model and how does it differ from source-sink model?

A

There is no sink but a degradation in the system as the molecules travel away = exponentially decaying function as chemical get further away from the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the decay length and its equation?

A

Lambda = decay length = sqrt (D/k)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define signal interpretation

A

How cells will change their fate depending on morphogen gradient

Magnitude and duration of the morphogen signal can activate different gen regulatory networks

19
Q

Why don’t cells just revert when the signal is no longer present?

A

Memory is retained to ensure the cell doesn’t forget its identity

This is carried out due to positive autoregulation = bistability

20
Q

What is important about double positive/negative feedback loops?***

A

Either both are ON or OFF

Important for decision-making

21
Q

What is the lock-on mechanism?

A

Lock-on mechanism in double positive and negative feedback loops facilitates robust decision-making in developmental processes.

Positive feedback amplifies specific cell fates, while negative feedback provides stability and control, leading to irreversible commitments that are essential for the proper organization and function of developing tissues.

This mechanism ensures that once a cell has made a decision about its fate, it is effectively locked into that state, supporting the intricate patterns and structures observed in biological systems.

22
Q

What properties do 3-node motifs have?

A

Regulated feedback
Memory, persistence and bistability

23
Q

Why do transcriptional cascades generally have 3 different kinases/signalling molecules?

A

Temporal Delay = blocks transient signals
Amplification = small initial signal leads to large output

24
Q

Why are transcriptional cascades important in developmental networks?

A

Timescale of transcription cascades is well suited to guide developmental processes

25
Q

Give two examples of positional information models in development

A

Drosophila segment development = bicoid forms a morphogen gradient

Drosophila fly wing disc

26
Q

What is bicoid?

A

Morphogen and transcription factor

27
Q

What is the function of bicoid

A

Establishes anterior-posterior axis of drosophila embryo by diffusing away from the anterior

Bicoid mRNA situated at anterior of fruit fly egg during oogenesis
A series of genes get switched on in a temporal manner, causing spatial patterns to form

28
Q

What can proliferation rate determine?

A

Shape or size of tissue is determined by how fast the cell divides

29
Q

Name the two factors morphogen gradietns can control

A

Cell proliferation rate (cell growth)
Cell differentiation

30
Q

What pathway is Dpp found in, and what is its function??

A

Dpp controls growth

Via Hipp/Yorkie signalling pathway

31
Q

What happens to the morphogen gradients as the cell grows?

A

The morphogen gradient scales as cell grow to keep the correct proportions

32
Q

What is an EXPANDER and how does it interact with morphogen gradient expansion?

A

Expander degrades morphogen

As cell grows (undergoes cell division), expander concentration drop (diluted)

Degradation of morphogen decreases, so morphogen gradient expansion increases

33
Q

What feedback is gradient scaling explained by?

A

Positive feedback

Expander inhibits morphogen gradient expansion

Morphogen gradient expansion inhibits decay by dilution of expander due to cell growth/division

34
Q

What is the difference between RD upstream vs downstream of PI? ***

A

The reaction diffusion lays the groundwork for positional information

Positional information tells reaction-diffusion where to act

35
Q

What is the role of symmetry breaking?

A

To create asymmetric organs

36
Q

What are the molecules that generate left-right patterning of the heart, and what is their feedback loop?

A

Nodal-Lefty 2

Nodal = autoactivator and activates Lefty2
Lefty2 = inhibitor of Nodal

37
Q

What model is left-right patterning?

A

It is a large diffusion-reaction model, NOT positional information

High concentration of Nodal on left and low concentration on right, since Lefty2 restricts spread of Nodal to the right side

38
Q

How do cilia play a role in symmetry breaking?

A

Cilia are found on teh left-right organizer

Motile cilia move rapidly to create leftward direction flow of extracellular fluid
Flow is sensed by immotile (primary) cilia which are mechanoreceptors

39
Q

Define mechanoreceptor

A

Structure or protein that detect mechanical forces and transforms them into biochemical signals

40
Q

Example of RD upstream of PI

A

Nodal-Lefty2, which constitutes a Turing system

41
Q

Example of RD in parallel with PI

A

Limb bud formation due to Shh as key morphogen to establish body plan

42
Q

How does Shh signalling and BMP-Wnt-Sox9 generate differnt digits?

A

Shh is positional information
BMP-Wnt-Sox9 is reaction diffusion

43
Q

Example of RD downstream of PI

A

Limb formation by Hox genes and FGF

Downstream in this context means that these systems rely on previously established positional cues to guide further development.

44
Q
A

Pattern Formation (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions