Cell Life Cycle and Reproduction
The cell cycle (cell-division cycle), is a series of events that take place in a cell leading to its division and duplication. The
main phases of the cell cycle are interphase, nuclear division, and cytokinesis . Cell division produces two daughter cells.
In cells without a nucleus (prokaryotic), the cell cycle occurs via binary fission.
Interphase
Gap1(G1)- Cells increase in size. The G1checkpointcontrol mechanism ensures that everything is ready for DNA
synthesis.
Synthesis(S)- DNA replication occurs during this
phase.
DNA Replication The process in which DNA makes a duplicate
copy of itself.
Semiconservative Replication The process in which the DNA
molecule uncoils and separates into two strands. Each original
strand becomes a template on which a new strand is
constructed, resulting in two DNA molecules identical to the
original DNA molecule.
Gap 2(G2)- The cell continues to grow.
The G2checkpointcontrol mechanism ensures that
everything is ready to enter the M (mitosis) phase and divide.
Mitotic(M) refers to the division of the nucleus. Cell growth stops at this stage and cellular energy is focused on the
orderly division into daughter cells. A checkpoint in the middle of mitosis (Metaphase Checkpoint) ensures that the cell is
ready to complete cell division. The final event is cytokinesis, in which the cytoplasm divides and the single parent cell
splits into two daughter cells.
Reproduction
Cellular reproduction is a process by which cells duplicate their contents and then divide to yield multiple cells with
similar, if not duplicate, contents.
Mitosis
Mitosis- nuclear division resulting in the production of two somatic
cells having the same genetic complement (genetically identical) as
the original cell.
As mitosis begins they condense and become visible under a light
microscope. They appear as sister chromatids joined at the
centromere. Mitosis is divided into 4 stages.
Prophase- nuclear envelope disintegrates and a spindle of
microtubules forms. Centrioles may help organize the spindle as in
this animal cell. The chromosomes begin to move toward the
midplane of the spindle
Metaphase- When they are on the midplane with centromeres
attached to spindle fibers
Anaphase- centromeres separate and the sister chromatids, now
termed chromosomes, are pulled toward opposite poles of the
spindle.
Telophase- a nuclear envelope forms around each set of
chromosomes, the spindle disappears and the chromosomes
decondense.
The cell cycle (cell-division cycle), is a series of events that take place in a cell leading to its division and duplication. The
main phases of the cell cycle are interphase, nuclear division, and cytokinesis . Cell division produces two daughter cells.
In cells without a nucleus (prokaryotic), the cell cycle occurs via binary fission.
Interphase
Gap1(G1)- Cells increase in size. The G1checkpointcontrol mechanism ensures that everything is ready for DNA
synthesis.
Synthesis(S)- DNA replication occurs during this
phase.
DNA Replication The process in which DNA makes a duplicate
copy of itself.
Semiconservative Replication The process in which the DNA
molecule uncoils and separates into two strands. Each original
strand becomes a template on which a new strand is
constructed, resulting in two DNA molecules identical to the
original DNA molecule.
Gap 2(G2)- The cell continues to grow.
The G2checkpointcontrol mechanism ensures that
everything is ready to enter the M (mitosis) phase and divide.
Mitotic(M) refers to the division of the nucleus. Cell growth stops at this stage and cellular energy is focused on the
orderly division into daughter cells. A checkpoint in the middle of mitosis (Metaphase Checkpoint) ensures that the cell is
ready to complete cell division. The final event is cytokinesis, in which the cytoplasm divides and the single parent cell
splits into two daughter cells.
Reproduction
Cellular reproduction is a process by which cells duplicate their contents and then divide to yield multiple cells with
similar, if not duplicate, contents.
Mitosis
Mitosis- nuclear division resulting in the production of two somatic
cells having the same genetic complement (genetically identical) as
the original cell.
As mitosis begins they condense and become visible under a light
microscope. They appear as sister chromatids joined at the
centromere. Mitosis is divided into 4 stages.
Prophase- nuclear envelope disintegrates and a spindle of
microtubules forms. Centrioles may help organize the spindle as in
this animal cell. The chromosomes begin to move toward the
midplane of the spindle
Metaphase- When they are on the midplane with centromeres
attached to spindle fibers
Anaphase- centromeres separate and the sister chromatids, now
termed chromosomes, are pulled toward opposite poles of the
spindle.
Telophase- a nuclear envelope forms around each set of
chromosomes, the spindle disappears and the chromosomes
decondense.
