Class 5 PDF-3 - Denis Maxwell PDF

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Denis Maxwell...

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Class 5: Molecular Evolution & Convergence

A

GlsA, one last time

Chlamy Volvox

Chlamy Volvox

B

Neutral theory of molecular evolution

The Molecular clock

Degree of constraint also affects rate of evolution

Functional versus sequence convergence • Does convergence onto similar function come about by sequence convergence onto similar sequences?

Eye

Eyespot

Evolutionary time

Complexity

Complexity

Channelrhodopsin vs rhodopsin….homologous or not?

Evolutionary time

Channelrhodopsin and rhodopsin are very different

Type 1 versus Type 2 Opsins

Channelrhodopsin

n io iss m l ns ra n na ot ctio mo r u r a f Ne Ol Ho

Rhodopsin

GPCR (G-protein coupled receptors)

Bacteriorhodopsin

Membrane Bacteriorhodopsin ATP Synthase

Convergent evolution: Digestive lysozyme • Lysozyme - Enzyme, antibacterial activity. – Attacks bacterial cell wall. – Found in blood, tears, mucus, egg white.

Cow

Human

Langur Phylogenetic tree

Hoatzin

Rat

Baboon

Digestive lysozyme sequences have converged • Digestive and non-digestive lysozymes fall into two phylogenetic groups: Amino acid position 14

Type A

Type B

D – Aspartic acid N - Asparagine

21

41

75

76

83

87

126

Hoatzin E Pigeon R Horse A

E V G

E T R

D N N

G A A

E K K

N D E

K R A

Human Langur Baboon Rat Cow Chicken

R K R Y K R

R E Q Q K Q

N D N N D N

A A A A G L

A A A A E A

D N D D N S

Q K Q R E R

R K R R K R...