Phyllotaxy

This is usually are of four types – alternate, opposite, spiral and whorled

In alternate type of phyllotaxy, a single leaf arises at each node in alternate manner, as in china rose, mustard and sunflower plants

Phyllotaxy

In opposite type, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants.

If more than two leaves arise at a node and form a whorl, it is called whorled, as in Alstonia (Devil Tree) Apocynaceae

Spiral phyllotaxy

Fibonacci sequence

Golden Angle

the divergence angle between successively arising leaves is fixed at the golden angle of 137.5°

TLS Online TPP Program

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#XL - T Zoology

The bacterial toxins that cause cholera and pertussis are enzymes that catalyze transfer of the ADP ribose moiety.

TLS Online TPP Program

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#XL - T Zoology

RTK ligands- NGF, PDGF, FGF, EGF

TLS Online TPP Program

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#XL - T Zoology

All RTKs have a cytosolic domain with protein tyrosine kinase activity

TLS Online TPP Program

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#XL - T Zoology

The EGFR specifically binds EGF in a lock-and-key type of mechanism.

TLS Online TPP Program

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#XL - T Zoology

The function of a growth factor-  stabilize receptor dimerization

TLS Online TPP Program

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#XL - T Zoology

HER1 & HER4, can form stable homodimers after binding a growth factor.