2. characterize the phases of the cell cycle and their
control points;
describe the stages of mitosis/meiosis given
2n=46;
discuss crossing over and recombination in
meiosis;
explain the significance or applications of
mitosis/meiosis; and
identify disorders and diseases that result from
the malfunction of the cell during the cell cycle.
Learning Competencies
4.
Cells go through a cycle of alternating
stages of division and rest from
division. This is called the Cell cycle.
The non-dividing stage, which is
devoted largely to cell growth, is called
interphase.
Introduction
6. Interphase includes three phases, as follows:
G1 phase is the period when the cell increases
in size in preparation for cell division.
S phase is the period during which DNA is
synthesized and chromosomes are replicated.
Each strand of the double-stranded
chromosome produced is called a sister
chromatid.
G2 phase is the period when the cell continues
to synthesize RNA and proteins and increase in
size.
Mitosis
7. Prophase is when chromosomes coil
up into rod-shaped structures, nucleoli
and nuclear membrane disappear and
spindle fibers are formed.
Metaphase involves the alignment of
double-stranded chromosomes at the
equatorial plate, with the kinetochores
attaching the chromosomes to the
spindle fibers.
Mitosis
8. Anaphase begins with the centromeres
and ends with the migration of single-
stranded chromosomes to the poles.
Telophase is also known as ‘reverse
prophase’ since it involves the
uncoiling of chromosomes,
reappearance of the nucleoli and
nuclear membrane, and dissappearance
of the spindle fibers.
Mitosis
9. Cytokinesis in plants involves the
formation of a cell plate that eventually
develops into the cell wall and the
middle lamella. In animal cells, the
formation of a cleavage furrow occurs.
Mitosis
10. 1. What is the diploid chromosome
number (2N) of the cell?
2. How many kinds of chromosomes
does the cell contain? How are they
represented in the drawing?
3. Are the chromosomes at prophase
single-stranded or double-stranded?
4. What attaches the chromosome to the
spindle fiber during metaphase?
Study the diagrammatic representation
of the stages of mitosis on the board
11. 5. How many chromosomes are there in
the cell at metaphase?
6. How many chromosomes are in the cell
at anaphase? Are the chromosomes
single-stranded or double-stranded?
7. How many chromosomes are present
in each nucleus formed at telophase?
Study the diagrammatic representation
of the stages of mitosis on the board
14.
The sex cells are produced through a
type of nuclear division that reduces
chromosome number to half of that
parent cell. This reduction-division is
called meiosis. Meiosis involves two
consecutive divisions, Meiosis I and
Meiosis II.
Meiosis
15.
1. How many chromosomes attach to each
spindle fiber during Metaphase I?
2. How many chromosomes are there in the
cell at Metaphase I?
3. How many chromosomes are in the cell at
Anaphase I? Are the chromosomes single-
stranded or double-stranded?
4. How many chromosomes are present in
each nucleus formed at telophase I?
Query?!
There are two common types of cell division that cells may undergo, namely, mitosis and meiosis. Strictly speaking mitosis and meiosis are types of nuclear division of the cytoplasm referred to as cytokinesis.
Interphase—Most actively dividing cells spend some 90 percent of their time at this stage.
When cells divide, two parts may be involved, namely, the nucleus and the cytoplasm. The division of the nucleus is called mitosis and the division of the cytoplasm is called cytokinesis. Strictly speaking, mitosis is a type of nuclear division that produces 2 daughter nuclei, each containing exactly the same number of chromosomes as the parent nucleus.
Some cells complete this cycle of interphase and mitosis within 24 hours, while others may take years before they go through the process of cell division. The cells at the apical meristem of an onion root divides every 20 hours. The epithelial cells in your intestine divide once every 10 hours.
Interphase—Most actively dividing cells spend some 90 percent of their time at this stage.
When cells divide, two parts may be involved, namely, the nucleus and the cytoplasm. The division of the nucleus is called mitosis and the division of the cytoplasm is called cytokinesis. Strictly speaking, mitosis is a type of nuclear division that produces 2 daughter nuclei, each containing exactly the same number of chromosomes as the parent nucleus.
G1-RNA and proteins including enzymes needed for making DNA are synthesized.
S pahse- each strand of the double-stranded chromosomes produced is called a sister chromatid.
G1 prepare for the next division or they may go into an arrested, quiescent stage known as G0 state to differentiate. Some cells, such as nerve cells and blood cells, remain in G0 all their lives. Mature red blood cells (RBCs) do not replicate due to a lack of a nucleus, DNA and most of the metabolic systems needed for mitosis. ... RBCs are derived from large erythroblasts in bone marrow which undergo mitosis at high rate under the influence of various hormones.
G1-RNA and proteins including enzymes needed for making DNA are synthesized.
S pahse- each strand of the double-stranded chromosomes produced is called a sister chromatid.
G1 prepare for the next division or they may go into an arrested, quiescent stage known as G0 state to differentiate. Some cells, such as nerve cells and blood cells, remain in G0 all their lives. Mature red blood cells (RBCs) do not replicate due to a lack of a nucleus, DNA and most of the metabolic systems needed for mitosis. ... RBCs are derived from large erythroblasts in bone marrow which undergo mitosis at high rate under the influence of various hormones.
Because centrioles function in cell division, the fact that neurons lack these organelles is consistent with the amitotic nature of the cell. ... Some cells in human body never divide and one such cell is neuron. They lack centrioles and hence cannot perform mitosis. So nerve cells do not divide.
G1-RNA and proteins including enzymes needed for making DNA are synthesized.
S pahse- each strand of the double-stranded chromosomes produced is called a sister chromatid.
G1 prepare for the next division or they may go into an arrested, quiescent stage known as G0 state to differentiate. Some cells, such as nerve cells and blood cells, remain in G0 all their lives. Mature red blood cells (RBCs) do not replicate due to a lack of a nucleus, DNA and most of the metabolic systems needed for mitosis. ... RBCs are derived from large erythroblasts in bone marrow which undergo mitosis at high rate under the influence of various hormones.
G1-RNA and proteins including enzymes needed for making DNA are synthesized.
S pahse- each strand of the double-stranded chromosomes produced is called a sister chromatid.
G1 prepare for the next division or they may go into an arrested, quiescent stage known as G0 state to differentiate. Some cells, such as nerve cells and blood cells, remain in G0 all their lives. Mature red blood cells (RBCs) do not replicate due to a lack of a nucleus, DNA and most of the metabolic systems needed for mitosis. ... RBCs are derived from large erythroblasts in bone marrow which undergo mitosis at high rate under the influence of various hormones.
G1-RNA and proteins including enzymes needed for making DNA are synthesized.
S pahse- each strand of the double-stranded chromosomes produced is called a sister chromatid.
G1 prepare for the next division or they may go into an arrested, quiescent stage known as G0 state to differentiate. Some cells, such as nerve cells and blood cells, remain in G0 all their lives. Mature red blood cells (RBCs) do not replicate due to a lack of a nucleus, DNA and most of the metabolic systems needed for mitosis. ... RBCs are derived from large erythroblasts in bone marrow which undergo mitosis at high rate under the influence of various hormones.
G1-RNA and proteins including enzymes needed for making DNA are synthesized.
S pahse- each strand of the double-stranded chromosomes produced is called a sister chromatid.
G1 prepare for the next division or they may go into an arrested, quiescent stage known as G0 state to differentiate. Some cells, such as nerve cells and blood cells, remain in G0 all their lives. Mature red blood cells (RBCs) do not replicate due to a lack of a nucleus, DNA and most of the metabolic systems needed for mitosis. ... RBCs are derived from large erythroblasts in bone marrow which undergo mitosis at high rate under the influence of various hormones.
G1-RNA and proteins including enzymes needed for making DNA are synthesized.
S pahse- each strand of the double-stranded chromosomes produced is called a sister chromatid.
G1 prepare for the next division or they may go into an arrested, quiescent stage known as G0 state to differentiate. Some cells, such as nerve cells and blood cells, remain in G0 all their lives. Mature red blood cells (RBCs) do not replicate due to a lack of a nucleus, DNA and most of the metabolic systems needed for mitosis. ... RBCs are derived from large erythroblasts in bone marrow which undergo mitosis at high rate under the influence of various hormones.
