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

TLS Online TPP Program

#Id: 8633

#XL - T Zoology

Mutating or deleting the destruction box in mitotic cyclins prevented their ubiquitination and blocked cells from exiting mitosis.

TLS Online TPP Program

#Id: 8634

#XL - T Zoology

At the metaphase to anaphase transition, APC/C bound to Cdc20 targets cyclins A /B and securin for degradation.

TLS Online TPP Program

#Id: 8635

#XL - T Zoology

During late anaphase, telophase and G1, APC/C bound to Cdh1 targets B type cyclins and geminin for degradation.

TLS Online TPP Program

#Id: 8637

#XL - T Zoology

The G1 cyclin-CDK complex (Cln3-CDK in yeast) stimulates the formation of G1/S phase cyclin-CDKs, which initiate bud formation, centrosome duplication, and DNA replication.

TLS Online TPP Program

#Id: 8638

#XL - T Zoology

Once sufficient Cln3 is synthesized from its mRNA, Cln3-CDK complexes phosphorylate and inactivate the transcriptional repressor Whi5.

TLS Online TPP Program

#Id: 8639

#XL - T Zoology

Phosphorylation of Whi5 promotes its export out of the nucleus, allowing the transcription factor complex SBF to induce transcription of the G1/S phase cyclin genes CLN1 and CLN2.