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By the end of this section, you will be able to:
  • Describe the three stages of interphase
  • Discuss the behavior of chromosomes during karyokinesis
  • Explain how the cytoplasmic content is divided during cytokinesis
  • Define the quiescent G 0 phase

The cell cycle    is an ordered series of events involving cell growth and cell division that produces two new daughter cells. Cells on the path to cell division proceed through a series of precisely timed and carefully regulated stages of growth, DNA replication, and division that produces two identical (clone) cells. The cell cycle has two major phases: interphase and the mitotic phase ( [link] ). During interphase    , the cell grows and DNA is replicated. During the mitotic phase    , the replicated DNA and cytoplasmic contents are separated, and the cell divides.

Like a clock, the cell cycles from interphase to the mitotic phase and back to interphase. Most of the cell cycle is spent in interphase, which is subdivided into G_{1}, S, and G_{2} phases. Cell growth occurs during G_{1}, DNA synthesis occurs during S, and more growth occurs during G_{2}. The mitotic phase consists of mitosis, in which the nuclear chromatin is divided, and cytokinesis, in which the cytoplasm is divided, resulting in two daughter cells.
The cell cycle consists of interphase and the mitotic phase. During interphase, the cell grows and the nuclear DNA is duplicated. Interphase is followed by the mitotic phase. During the mitotic phase, the duplicated chromosomes are segregated and distributed into daughter nuclei. The cytoplasm is usually divided as well, resulting in two daughter cells.

Interphase

During interphase, the cell undergoes normal growth processes while also preparing for cell division. In order for a cell to move from interphase into the mitotic phase, many internal and external conditions must be met. The three stages of interphase are called G 1 , S, and G 2 .

G 1 Phase (first gap)

The first stage of interphase is called the G 1 phase    (first gap) because, from a microscopic aspect, little change is visible. However, during the G 1 stage, the cell is quite active at the biochemical level. The cell is accumulating the building blocks of chromosomal DNA and the associated proteins as well as accumulating sufficient energy reserves to complete the task of replicating each chromosome in the nucleus.

S phase (synthesis of dna)

Throughout interphase, nuclear DNA remains in a semi-condensed chromatin configuration. In the S phase    , DNA replication can proceed through the mechanisms that result in the formation of identical pairs of DNA molecules—sister chromatids—that are firmly attached to the centromeric region. The centrosome is duplicated during the S phase. The two centrosomes will give rise to the mitotic spindle    , the apparatus that orchestrates the movement of chromosomes during mitosis. At the center of each animal cell, the centrosomes of animal cells are associated with a pair of rod-like objects, the centrioles , which are at right angles to each other. Centrioles help organize cell division. Centrioles are not present in the centrosomes of other eukaryotic species, such as plants and most fungi.

G 2 Phase (second gap)

In the G 2 phase    , the cell replenishes its energy stores and synthesizes proteins necessary for chromosome manipulation. Some cell organelles are duplicated, and the cytoskeleton is dismantled to provide resources for the mitotic phase. There may be additional cell growth during G 2 . The final preparations for the mitotic phase must be completed before the cell is able to enter the first stage of mitosis.

Questions & Answers

where is the pectoral gridle located?
Tiania Reply
What is hypotonic
Bright Reply
what is hypotonic
Dangaya
the difference between the two cells
Obeng Reply
explain the courses and the correction of lon term sightedness and short term sightedness
Isaac Reply
why drinking excess alcohol causes thirst and dehydration
uwikuzo Reply
Can we chat about nutrition please?
Elia
yes
Uzair
sure
Uzair
Uhm why is it so important to follow the nutritional process?
Elia
what is reproduction
smart Reply
it is d act of bringing young ones to life
Oyebanji
to ensure survival of a species🚴‍♀️
Michelle
what is a genotype
Collins
what is hazardous
smart
a cell is the smallest unit of a living thing. so we all have cell
smart
It is the formation of a zygote resulting from the fusion of the sperm cell with the ovum.Thus,this results in the production of new species which are genetically dissimilar from their parent cells.
Pallavi
what is size of cell
Mohd Reply
what is size of Hart
Mohd
nanometers=um sign thingie
Michelle
microns=nanometers
Michelle
monomers and polymers of nucleic acids?
Jyrl Reply
dna and rna involvement
Michelle
give me the elements of the soil
Iguma Reply
Air, water, organic matter, inorganic matter
Tshwano
soil water humus air
Veronicah
yap
Beloved
silica, iron
Patience
potassium, sulfur, calcium, carbon
Michelle
what is cell
iyaji Reply
A cell is a smallest fundamental unit of a living organisms.
Kem
the basic structural and functional unit of life
Patience
what is size of cell
Mohd
all things are made up of.....all things cannot exist without pre-exisiting cells...check out the 16th ce tury to learn more about microscope use and cells. i will give a hint: Mr. L.
Michelle
we are all made of cells
Michelle
Nutrition - sensitive intervention
Therowda Reply
what does the sori In fern mean
arhin Reply
biology is the study .exactly what is life?
Jerry
i'm sorry , the study of life
Jerry
How is food distributed to all parts of cytoplasm
Therowda
how can U identify a person through his blood
Frankyx Reply
through genetic fingerprinting where specific DNA sequences in a person genome can be identified.
Pallavi
by help of genetics and DNA test
Meerbadini
can it also be detected using an RNA test
Frankyx
environmental biology
Ojesola Reply
what is phytoplankton
Ojesola
What is anabolism
Treasure Reply
the break down of substance
Aunty

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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