Indicate true (T) and false (F) statements below regarding cytokinesis in animal cells. Choose the correct answer represented by a four-letter string composed of letters T and F only, e.g. TFFF.
( ) The force for cytokinesis is generated by kinesin motors on microtubule bundles that form the contractile ring.
( ) As the contractile ring constricts, its thickness increases to keep a constant volume.
( ) The midbody forms from bundles of actin and myosin II.
( ) Local activation of Ran GTPase triggers the assembly and contraction of the contractile ring.
1) Kinesin is a family of motor proteins that work by generating a force along the microtubules to promote the formation of the contractile ring made up of actin and myosin microfilaments. When ATP (adenosine triphosphate) undergoes continuous hydrolysis, it generates free energy that is utilized by the kinesins to move along actin microfilaments and generate force to form the contractile ring. The statement is True.
2) The contractile ring undergoes constriction and a midbody formation occurs followed by abscission. It has been observed that after the beginning of ingression of the cell membrane and subsequent furrow formation, the actin filaments start disassembling aided by Rab35 GTPase. It was also found in a study that the volume of the actin filaments decreases as constriction proceeded, and the ring gets smaller. The ring perimeter decreases with increasing constriction. The statement is False.
3) The midbody structure is formed by continuous ingression of the cell membrane. It is an electron dense structure, proteinaceous in nature. Studies show that it is a tightly packed, antiparallel microtubule bundle at its core, whereas periphery composition is unclear. However, it does have a number of proteins like MKLP1(a kinesin motor protein) KIF4(a chromokinesin), and PRC1(microtubule-bundling protein for cytokinesis 1), apart form actin and myosin filaments.
4) Ran GTPase is one of the proteins that act by promoting the arrangement of microtubules at the equator of the cell. it is activated after the telophase and its activation cause assembly and further contraction of the contractile ring. The statement is True.
- Correct answer is - TFFT
Indicate true (T) and false (F) statements below regarding cytokinesis in animal cells. Choose the correct...
Indicate true (T) and false (F) statements below regarding cytokinesis in animal cells. Choose the correct answer represented by a four-letter string composed of letters T and F only, e.g. TFFF. ( ) The force for cytokinesis is generated by kinesin motors on microtubule bundles that form the contractile ring. ( ) As the contractile ring constricts, its thickness increases to keep a constant volume. ( ) The midbody forms from bundles of actin and myosin II. ( ) Local...
Indicate true (T) and false (F) statements below regarding signaling in plants. Your answer would be a four-letter string composed of letters T and F only, e.g. TTTF. ( ) Since multicellularity evolved before the divergence of the plant and animal lineages, plants have homologs of most animal signaling proteins, such as nuclear receptors, Ras, JAK, and Notch. ( ) Receptor tyrosine kinases are the largest class of cell-surface receptors in plant cells. ( ) Both plants and animals use...