Intro To Evolution 2

Question 1

Evolution of cell

What is the earliest cells?

Answer 1

Prokaryotic cells

Question 2

What do plastic genomes encode for?

Answer 2

They encode proteins necessary for plastid function

Question 3

Evolution of multicellularity

Answer 3

Is usually a characteristic of eukaryotes

Question 4

What are 4 basic processes of multicellularity?

Answer 4

Spatial organisation, change in form, growth and differentiation

Question 5

Describe the evolution of the eye?

Answer 5

Origin of eye components varies
Type of photoreceptor=> ciliary or microvillar
Position of retina
Diversity of eye suggests that they have evolved several times independently
All eukaryotes use homologous family of proteins called opsin to detect light
Opsins are G protein coupled receptors that convert light to nerve impulses
Eukaryotic opsins share sequence homology + have diverged to detect different wavelengths of light

Question 6

What are paralogues?

Answer 6

Are homologues within same species

Question 7

What are orthologues?

Answer 7

Are homologues between species

Question 8

Pax 6 + eye development

Answer 8

Eyeless is orthologous to Pax 6 in humans (aniridia) + mouse (small eye)
Ectopic expression of eyeless in drosophila > ectopic eye
Mouse pax 6 gene functions in fly
Pax 6 involved in eye development throughout the animal kingdom

Question 9

Is pax 6 the master gene?

Answer 9

Probably not
Other genes can induce ectopic eyes
Animals without eyes have Pax 6 gene
Pax 6 gene is present in + required for other tissues
More likely that it organises a gene network required for eye formation

Question 10

Eye loss during evolution

Answer 10

Some animals have evolved from surface dwelling forms to underground forms
Eye loss is common feature in such animals
Exemplified by Mexican blind fish (Astyanax Mexicanus)

Question 11

What makes humans human?

Answer 11

Compare genomic sequences of humans with that of closely related species
Identify sequences conserved in other animals but lost in humans——hCONDELS (human, conserved, deleted)
583 regions identified across all chromosomes

Question 12

Spread of neanderthal and Denisovan DNA

Answer 12

Europe has high incidence of Neanderthal DNA
Asia, there is more predominance of
Denisovan DNA
In Africa, there is very little ingress of Neanderthal DNA