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Development > Evo-devo > Flashcards

Evo-devo Flashcards

1
Q

Evolution refers to changes on which 4 scales?

A
  1. Genomic
  2. Morphological
  3. Physiological
  4. Behavioural
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2
Q

The same species can have highly different morphologies. Give 2 examples.

A
  1. Breeds of dog.

2. Races of human.

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3
Q

What does ‘evo-devo’ mean?

A

Evolution arises from changes to development.

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4
Q

What do exons do?

A

Code for proteins.

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5
Q

What do introns do?

A

Control gene expression.

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6
Q

What do enhancer regions do?

A

Control transcription and thus protein synthesis.

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7
Q

What is a DNA binding motif and why do enhancer regions each have unique ones?

A

A specific sequence for a TF to bind to. Enhancer regions all have different TFs so DNA binding motifs are unique.

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8
Q

What does an activator do?

A

Bind to an enhancer region and stimulate transcription.

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9
Q

What does a repressor do?

A

Bind to an enhancer region and suppress transcription.

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10
Q

Give 3 examples of cytoplasmic determinants (CDs).

A

Proteins, mRNA and morphogens.

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11
Q

Cytoplasmic determinants are asymmetrically distributed. What does this mean during cell division?

A

The resultant daughter cells will have different compositions of CDs and thus differentiate independently.

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12
Q

Why are gap junctions important for the control of cell signalling?

A

CDs have to diffuse through gap junctions, which can affect speed and distribution.

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13
Q

Many cell-signalling pathways are ligand-gated. Give an example.

A

Wnt signalling.

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14
Q

What is the main point of Wnt signalling?

A

Dsh inhibits GSK3-beta so it can no longer degrade beta-catenin. Beta-catenin then moves into the nucleus to activate the hedgehog pathway.

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15
Q

What does pax6 control?

A

The eye.

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16
Q

Pax6 can be moved between species and still produce the same result. Give an example of this.

A

Mouse pax6 can be inserted into drosophila. Mice have camera eyes and drosophila has a compound eye. Insertion of mouse pax6 still produces a compound eye in drosophila.

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17
Q

What do transplant experiments in pax6 show?

A

It activates the same signalling pathway in all organisms, showing it is highly conserved.

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18
Q

If pax6 can be transplanted between animals, what does this say about gene expression?

A

The coding sequence is the only part that needs to be conserved - what creates differences between species is the non-coding, regulatory regions.

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19
Q

Define microevolution.

A

Comparing differences between populations of the same species, e.g. races of human.

20
Q

Define macroevolution.

A

Comparing different species.

21
Q

Define comparative embryology.

A

Studying the differences in gene regulation and expression between species.

22
Q

Define experimental embryology.

A

Testing gene regulation and expression by experimental manipulation of embryos.

23
Q

Which signalling pathway is upregulated in Darwin’s finches with long, pointed beaks?

A

Calmodulin-dependent.

24
Q

What role does BMP4 expression play in Darwin’s finches?

A

Control beak size: lots of BMP4 produces a large beak.

25
Q

Which gene supresses BMP4 to give a narrow, short beak?

A

Noggin

26
Q

What can mRNA microarray studies show us?

A

Gene expression

27
Q

What 2 genes are combined to determine beak shape in Darwin’s finches?

A

BMP4 and Calmodulin (CaM)

28
Q

What does high BMP4 produce?

A

A large beak

29
Q

What does high calmodulin produce?

A

A long beak

30
Q

What can a ‘quantitive trait locus’ or QTL tell us about the genome and why?

A

Whether it has changed because these traits are measurable.

31
Q

What is Astyanax mexicanas?

A

A Mexican cavefish

32
Q

The ancestral surface form of A. mexicanus has eyes with normal pigment. The derived cavefish has no eyes and no pigment. If you cross these, what is the F1 hybrid like?

A

Small eyes with less pigment.

33
Q

The ancestral surface form of A. mexicanus has eyes with normal pigment. The derived cavefish has no eyes and no pigment. If you cross these, then cross the F1, what is the F2 hybrid like?

A

A range of phenotypes ranging from normal to eyeless.

34
Q

Fro studies like those on A. mexicanus what can we determine?

A

Which loci are involved in a particular trait.

35
Q

There are marine and freshwater species of stickleback. Which species has a higher degree of armour?

A

Marine.

36
Q

How many bp in the sequence that codes for stickleback armour?

A

4 million

37
Q

What is EDA and why is it important in sticklebacks?

A

Ectodysplasin, a secreted signalling molecule that gives rise to hair follicles.
There are different variations of this gene in geographically distinct populations.

38
Q

Why are freshwater sticklebacks missing their pelvic fins?

A

They have lost expression of the Pitx1 gene as the TF binding sites have been modified.

39
Q

What are pelvic fins homologous to in mammals?

A

The hind limbs.

40
Q

What happens if you inject a freshwater stickleback with Pitx1?

A

It grows pelvic fins.

41
Q

In A. mexicanus, the pax6 gene is separated into two regions of expression by what?

A

SHH (sonic hedgehog TF).

42
Q

When does Cyclops form in sticklebacks?

A

When SHH fails to separate the 2 coding regions of pax6.

43
Q

In which type of A. mexicanus is SHH expression greater and why?

A

The cavefish - it causes the eyes to get smaller and apoptosis to occur so the eye dies away completely.

44
Q

What other phenotypic changes are observed with increased SHH expression, common in the cave form of A. mexicanus?

A

Increased jaw size and more tastebuds as fish cannot rely on sight for prey capture.

45
Q

What is characteristic about the pax6 gene in the cave form of A. mexicanus?

A

The gap between the two coding regions is much larger as the SHH region is larger.

46
Q

What happens when SHH is downregulated in A. mexicanus?

A

The eyes are closer together, the jaw is narrower and there are less tastebuds.

Development (18 decks)

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