III. Vascular plants  (pteridophyta)

EVOLUTION OF LEAVES

spore-bearing leaves called sporophylls

In terms of size and complexity, leaves can be classified as either microphylls or megaphylls

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Centrosomes contain γ tubulin, which forms specific ringlike complexes (γ TuRCs) that, have the ability to nucleate microtubules and form a bipolar spindle

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Mitotic spindle attach to chromosomes via specialized protein structures known as kinetochores

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Kinetochores assemble on regions of chromosomal DNA marked by a centromere-specific H3 histone variant called CENP-A.

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Amphitelic attachment, 

sister kinetochores attach to microtubules emanating from opposite spindle poles, they are stably attached

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Merotelic attachment 

A kinetochore can attach to microtubules emanating from both poles at the same time

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Syntelic attachment 

Both kinetochores of a sister chromatid pair can attach to microtubules from the same pole