Why is it important that the duration of cell-cycle phases be controllable in adult multicellular organisms? b. What is MFP? Describe how this complex affects the cell cycle. Solution SOME BRIEF DESCRIPTION WHICH HELP YOU TO UNDERSTAND QUESTION AND IT S ANSWER FOR MY KNOWLEDGE IT HELPS YOU NOTE ;------ (The cell grows . The duration of these cell cycle phases varies considerably in different kinds of cells. For a typical rapidly proliferating human cell with a total cycle time of 24 hours, the G1 phase might last about 11 hours, S phase about 8 hours, G2 about 4 hours, and M about 1 hour.) The cell cycle or cell-division cycle is the series of events that take place in a cell leading to its division and duplication of its DNA (DNA replication) to produce two daughter cells. In bacteria, which lack a cell nucleus, the cell cycle is divided into the B, C, and D periods. The B period extends from the end of cell division to the beginning of DNA replication. DNA replication occurs during the C period. The D period refers to the stage between the end of DNA replication and the splitting of the bacterial cell into two daughter cells. In cells with a nucleus, as in eukaryotes, the cell cycle is also divided into three periods: interphase, the mitotic (M) phase, and cytokinesis. During interphase, the cell grows, accumulating nutrients needed for mitosis, preparing it for cell division and duplicating its DNA. During the mitotic phase, the chromosomes separate. During the final stage, cytokinesis, the chromosomes and cytoplasm separate into two new daughter cells. To ensure the proper division of the cell, there are control mechanisms known as cell cycle checkpoints. The cell-division cycle is a vital process by which a single-celled fertilized egg develops into a mature organism, as well as the process by which hair, skin, blood cells, and some internal organs are renewed. After cell division, each of the daughter cells begin the interphase of a new cycle. Although the various stages of interphase are not usually morphologically distinguishable, each phase of the cell cycle has a distinct set of specialized biochemical processes that prepare the cell for initiation of cell divisions. Cell cycle checkpoints are control mechanisms in eukaryotic cells which ensure proper division of the cell. Each checkpoint serves as a potential point along the cell cycle, during which the conditions of the cell are assessed, with progression through the various phases of the cell cycle occurring when favorable conditions are met. Currently, there are three known checkpoints: the G1 checkpoint, also known as the restriction or start checkpoint or (Major Checkpoint); the G2/M checkpoint; and the metaphase checkpoint, also known as the spindle checkpoint. Effects of MULTIFOLIATE-PINNA, AFILA, TENDRIL-LESS and UNIFOLIATA genes on leafblade architecture in Pisum sativum In order to dissect the genetic regulation of leafblade morphogenesis, 16 genotypes of pea, constructed.

1. Why is it important that the duration of cell-cycle phases be controllable in adult multicellular
organisms? b. What is MFP? Describe how this complex affects the cell cycle.
Solution
SOME BRIEF DESCRIPTION WHICH HELP YOU TO UNDERSTAND QUESTION AND IT
S ANSWER FOR MY KNOWLEDGE IT HELPS YOU
NOTE ;------ (The cell grows . The duration of these cell cycle phases varies considerably in
different kinds of cells. For a typical rapidly proliferating human cell with a total cycle time of
24 hours, the G1 phase might last about 11 hours, S phase about 8 hours, G2 about 4 hours, and
M about 1 hour.)
The cell cycle or cell-division cycle is the series of
events that take place in a cell leading to its division and duplication of its DNA (DNA
replication) to produce two daughter cells. In bacteria, which lack a cell nucleus, the cell cycle is
divided into the B, C, and D periods. The B period extends from the end of cell division to the
beginning of DNA replication. DNA replication occurs during the C period. The D period refers
to the stage between the end of DNA replication and the splitting of the bacterial cell into two
daughter cells. In cells with a nucleus, as in eukaryotes, the cell cycle is also divided into three
periods: interphase, the mitotic (M) phase, and cytokinesis. During interphase, the cell grows,
accumulating nutrients needed for mitosis, preparing it for cell division and duplicating its DNA.
During the mitotic phase, the chromosomes separate. During the final stage, cytokinesis, the
chromosomes and cytoplasm separate into two new daughter cells. To ensure the proper division
of the cell, there are control mechanisms known as cell cycle checkpoints.
The cell-division cycle is a vital process by which a
single-celled fertilized egg develops into a mature organism, as well as the process by which
hair, skin, blood cells, and some internal organs are renewed. After cell division, each of the
daughter cells begin the interphase of a new cycle. Although the various stages of interphase are
not usually morphologically distinguishable, each phase of the cell cycle has a distinct set of
specialized biochemical processes that prepare the cell for initiation of cell divisions.
Cell cycle checkpoints are control mechanisms in eukaryotic cells which
ensure proper division of the cell. Each checkpoint serves as a potential point along the cell
cycle, during which the conditions of the cell are assessed, with progression through the various
phases of the cell cycle occurring when favorable conditions are met. Currently, there are three
known checkpoints: the G1 checkpoint, also known as the restriction or start checkpoint or
(Major Checkpoint); the G2/M checkpoint; and the metaphase checkpoint, also known as the

2. spindle checkpoint.
Effects of MULTIFOLIATE-PINNA, AFILA, TENDRIL-LESS and UNIFOLIATA genes on
leafblade architecture in Pisum sativum
In order to dissect the genetic regulation of leafblade
morphogenesis, 16 genotypes of pea, constructed by combining the wild-type and mutant alleles
of MFP, AF, TL and UNI genes, were quantitatively phenotyped. The morphological features of
the three domains of leafblades of four genotypes, unknown earlier, were described. All the
genotypes were found to differ in leafblade morphology. It was evident that MFP and TL
functions acted as repressor of pinna ramification, in the distal domain. These functions, with
and without interaction with UNI, also repressed the ramification of proximal pinnae in the
absence of AF function. The expression of MFP and TL required UNI function. AF function was
found to control leafblade architecture multifariously. The earlier identified role of AF as a
repressor of UNI in the proximal domain was confirmed. Negative control of AF on the UNI-
dependent pinna ramification in the distal domain was revealed. It was found that AF establishes
a boundary between proximal and distal domains and activates formation of leaflet pinnae in the
proximal domain.