the cell cycle and it's control(this should be in PJ1311)
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cell cycle
defined as ordered sequences of events that occurs in the cell in preparation of cell division
what are the two basic functions of the cell cycle
Copying cellular components and DNA duplication Dividing the cell so that components are distributed evenly to the daughter cells
do all cells divide?
No some cell can’t divide e.g, eye lens, nerve cell, heart cells.
in unicellular cells, what does the division of one cell result to
the reproduction of the entire organism
multicellular organisms depend on the cell cycle for?
growth of cells and the organism itself maintenance of cells repair of damaged cells
what happens at the G0 phase
Resting phase where cell has left cycle &has stopped dividing
what happens at the G1 phase
1st stage of Cell growth after cell division Preparation of chromosomes for replication Duplication of cellular components (cytoplasm and organelle) Cell carries on its normal metabolic activities G1 checkpoint (or restriction point); cell commits to division or exits from cell cycle
how many phases are there during interphase, name them
3 phases G1 S G2
what happens during the S phase
DNA replication
by which mechanism does DNA replication occur
semi-conservative
is cytokinesis part of mitosis
no, it follows mitosis
in which direction does the synthesis of DNA occur
from the 5’ end to the 3’ end
which molecule is required to initiate DNA synthesis
a primer
primer
short strand of DNA or RNA that serves as a starting point for DNA synthesis during replication
function of ligase
unwinds parental double helix
functions of binding proteins
they stabilise separate strands of the DNA double helix
primase function
add a primer to the template strand
DNA polymerase function
binds nucleotides to form new strands
DNA polymerase I (exonuclease) function
removes RNA primer and inserts the correct bases
ligase function
joins Okazaki fragments and seals in the sugar-phosphate backbone
what are some general features of DNA replication
DNA replication is semi conservative It is bidirectional process It proceed from a specific point called origin It proceed in 5’-3’ direction It occur with high degree of fidelity It is a multi-enzymatic process
mitosis
process by which cell separates chromosomes in its cell nucleus into two identical sets in two nuclei
duplicated chromosomes are known as? what are they held together by
chromatids centromere
what happens during the G2 phase
All cell structures needed for division are made (e.g.centrioles) Both organelles & proteins are synthesized Checkpoint for entry into M phase