Mitosis Cell Division Animation | Phases of mitosis | Cell Cycle
Summary
TLDRThis video script delves into the fascinating process of cell division, which allows a parent cell to split into two or more daughter cells. It covers the cell cycle's phases: G1, S, G2, and M, detailing the preparation and execution of division. The script also touches on checkpoints ensuring proper cell division and the significance of the mitotic spindle. It highlights the role of growth factors in re-entering the cell cycle and the variable duration cells spend in the G0 phase, depending on cell type.
Takeaways
- 🌿 Cell division is a biological process where a parent cell divides into two or more daughter cells.
- 🧬 A typical human cell contains 46 chromosomes, including 22 pairs of autosomes and two sex chromosomes.
- 🔄 The cell cycle is a series of stages that prepare a cell for division, with a typical duration of 24 hours for rapidly dividing cells.
- 🔢 The cell cycle is divided into four phases: G1, S, G2, and M, with G1 being the most variable in duration.
- 📈 The G1 phase is critical for the synthesis of RNA, proteins, and cell organelles necessary for cell division.
- 🔬 The S phase is when DNA replication occurs, resulting in two sister chromatids for each chromosome.
- 🛠️ The G2 phase involves further protein synthesis and preparation for mitosis, including organelle and cytoskeleton reorganization.
- 🧐 The M phase, or mitosis, includes stages like prophase, metaphase, anaphase, and telophase, where chromosomes are separated and the cell divides.
- 🔍 The G1 checkpoint ensures cells only enter the S phase when growth signals are present, preventing unregulated cell division.
- 🔄 The G2 checkpoint verifies DNA replication completeness and integrity before cells enter mitosis.
Q & A
What is cell division?
-Cell division is a biological process by which a parent cell divides into two or more daughter cells, duplicating each chromosome into two sister chromatids and distributing them equally to ensure each new cell has the same genetic material.
How many chromosomes does a typical human cell contain?
-A typical human cell contains 46 chromosomes, which include two copies of the 22 homologous chromosomes and two copies of the sex chromosomes.
What are the four phases of the cell cycle?
-The four phases of the cell cycle are G1 (Gap 1) phase, S (Synthesis) phase, G2 (Gap 2) phase, and M (Mitosis) phase.
What is the duration of the cell cycle for a rapidly dividing human cell?
-The total cell cycle time for a typical rapidly dividing human cell is 24 hours, with the shortest phase being 12 hours.
What happens during the G1 phase of the cell cycle?
-During the G1 phase, the cell synthesizes RNA, proteins, and cell organelles, and grows. It also prepares for mitosis by synthesizing proteins required for the mitotic spindle. A G1 checkpoint ensures that the cell does not enter the S phase without proper growth signals.
What is the main event of the S phase?
-The S phase is characterized by the replication of DNA, resulting in each chromosome having two copies, or sister chromatids, which are held together by cohesion proteins at the centromere.
What is the role of the G2 checkpoint in the cell cycle?
-The G2 checkpoint occurs at the end of the G2 phase and checks for DNA damage and the completeness of DNA replication. It ensures that the cell is ready to enter mitosis by facilitating the initiation of mitosis through phosphorylation of various proteins.
What are the four stages of mitosis?
-The four stages of mitosis are prophase, metaphase, anaphase, and telophase. These stages involve the condensation of DNA, alignment and separation of sister chromatids, and the physical division of the cell into two daughter cells.
What is the significance of the spindle checkpoint in mitosis?
-The spindle checkpoint, also known as the M checkpoint, occurs between metaphase and anaphase in mitosis. It ensures the correct alignment of chromosomes and sister chromatids at the equatorial plane before they are separated, preventing errors in chromosome distribution.
What is cytokinesis and how does it relate to cell division?
-Cytokinesis is the final step in cellular division where the cell physically divides into two daughter cells. It is characterized by the formation of a cleavage furrow in the cell membrane and the separation of the cell bodies, marking the end of one cell cycle and the beginning of two new ones.
What is the G0 phase and how does it differ from other phases of the cell cycle?
-The G0 phase is a resting phase where the cell exits the cell cycle and becomes quiescent until it receives external stimuli such as growth factors. Unlike other phases, G0 is not part of the active cell cycle and can last indefinitely, depending on the cell type.
Outlines
🌱 Cell Division and Cycle Overview
This paragraph introduces cell division, a critical biological process where a parent cell divides into two or more daughter cells. It discusses the typical human cell's 46 chromosomes, which include 22 pairs of homologous chromosomes and two sex chromosomes. During cell division, the cell's contents, including organelles and the cytoskeleton, are duplicated, and each chromosome is copied into two sister chromatids. The cell cycle, which includes the phases G1, S, G2, and M, is outlined as the sequence of events leading to the production of two identical daughter cells. The total cell cycle time for a rapidly dividing human cell is 24 hours, with the shortest phase being 12 hours. The paragraph also delves into the interphase, which includes G1, S, and G2 phases, preparing the cell for division. The G1 phase is highlighted for its variable duration and critical role in RNA, protein, and organelle synthesis, as well as the G1 checkpoint that ensures cells only divide with proper growth signals.
🔬 Detailed Cell Cycle Phases and Checkpoints
The second paragraph delves deeper into the specific phases of the cell cycle, focusing on the S, G2, and M phases. The S phase, lasting approximately 8 hours, is when the cell replicates its DNA, creating two copies of each chromosome known as sister chromatids. The G2 phase, approximately 2 to 5 hours long, is characterized by cell growth and preparation for division, including the synthesis of proteins required for mitosis. The M phase, or mitosis, involves the condensation of DNA into visible chromatids, their separation, and movement to opposite cell poles, culminating in cell division into two daughter cells. The paragraph also explains the checkpoints within the cell cycle, such as the G2 checkpoint that checks for DNA damage and replication completeness, and the spindle checkpoint that ensures correct chromosome alignment before separation. The paragraph concludes with a discussion of cytokinesis, the physical division of the cell, and the G0 phase, where cells exit the cell cycle and become quiescent until stimulated to re-enter the cycle.
Mindmap
Keywords
💡Cell Division
💡Chromosomes
💡Cell Cycle
💡Interphase
💡Mitosis
💡Sister Chromatids
💡Centromere
💡G1 Checkpoint
💡Cytokinesis
💡G0 Phase
Highlights
Cell division is a process where a parent cell divides into two or more daughter cells.
A typical human cell contains 46 chromosomes, including 22 pairs of homologous chromosomes and two sex chromosomes.
During cell division, the cell's contents, including organelles and the cytoskeleton, are duplicated.
The cell cycle is the sequence of events leading to cell division, typically taking 24 hours for a rapidly dividing human cell.
The cell cycle consists of four phases: G1, S, G2, and M, with G1 being the most variable in duration.
The G1 phase is critical for the synthesis of RNA, proteins, and cell organelles required for mitosis.
The G1 checkpoint ensures cells do not enter the S phase without proper growth signals.
The S phase is where the cell replicates its DNA, creating two copies of each chromosome.
Sister chromatids, formed during S phase, are held together by cohesion proteins at the centromere.
The G2 phase involves further protein synthesis and preparation for cell division.
The G2 checkpoint checks for DNA damage and ensures the completeness of DNA replication.
M phase is the final step in cellular division, where DNA condenses and sister chromatids are separated.
Prophase is characterized by the condensation of DNA into 46 pairs of sister chromatids.
Metaphase involves the alignment of sister chromatid pairs at the cell's center for separation.
The spindle checkpoint in metaphase ensures correct chromosome alignment before separation.
Anaphase is the stage where sister chromatids separate and move to opposite cell poles.
Telophase is marked by chromosome decondensation, nuclear membrane formation, and cell body division.
Cytokinesis is the physical division of the cell into two daughter cells, marked by cell membrane cleavage.
The G0 phase is a resting state where cells exit the cell cycle until stimulated by growth factors.
Growth factors initiate a signaling cascade necessary for cell division in response to external stimuli.
Transcripts
[Music]
cell division introduction cell division
is a process by which a parent cell
divides into two or more daughter cells
a typical human cell contains 46
chromosomes two copies of the 22
homologous chromosomes plus two copies
of the sex chromosome when the cell
divides it roughly doubles all of its
contents including organel and the
cytoskeleton and duplicates each
chromosome into two sister chromatids
the cell then splits the large double
cell into two identical daughter cells
each with the same 46 chromosomes as the
mother cell cell cycle it is the ordered
sequence of events that occur in a Cell
in the preparation of cell division to
produce two daughter cells the total
cell cycle time for a typical rapidly
dividing human cell is 24 hours and the
most minimum time is 12 hours the cell
cycle can be divided into four phases G1
Gap 1 phase s or DNA synthesis phase G2
Gap 2 phase M mitosis phase the cell
involves two phases interphase and
mitosis interphase further involves the
G1 phase or Gap One S phase synthesis
and G2 phase Gap 2 which prepare the
cell for division G not phase is not a
part of interphase the time taken for S
G2 and M are similar for most cell types
G1 phase lasts several hours to months S
phase lasts for 6 to 8 hours G2 phase
lasts approximately 2 to 5 hours and M
phase for 1 to 2 hours in contrast the
duration of G1 phase shows a vast
variation in a rapidly dividing phase G1
phase can be less than 2 hours in a
resting cell G1 phase can be Beyond 100
hours or more in ovaries primary us
sites remain in ditin stage of meosis
from fifth month of intrauterine life
until the period before ovulation begins
let's focus on events which takes place
during each phase G1 phase this phase
lasts for several hours to months and
occurs after
mitosis this phase is critical For the
synthesis of RNA proteins and cell
organel the synthesis of proteins that
are required for mitosis such as the
mitotic spindle is particularly
important important during this phase
there is one chromatid present per
chromosome the cell grows during this
phase nucleotide excision repair takes
place at the end of this phase there is
a G1 checkpoint before entering S phase
G1 checkpoint or restriction checkpoint
is a cell division checkpoint that
restricts entry into the synthesis or S
phase without growth signals that lift
this checkpoint cells will not divide
after this checkpoint cells become
committed to division loss of this
checkpoint for example from loss of p-53
function leads to unregulated cell
division S phase this phase lasts for
approximately 8 hours during the S phase
the cell replicates its DNA so that by
the end each chromosome has two copies
the copies are attached to each other by
cohesion proteins in a structure called
a centromere and together they're
referred to as sister chromatids each
pair of sister chromatids is considered
to be one chromosome because they are
just copies of the same genetic material
and still attached to one another this
phase of the cell cycle is where
histones the proteins that bind and
organized DNA are duplicated at this
point the cell has double the amount of
genetic material most mismatch repair
takes place during the S phase once the
S phase is initiated the cell must be
completed G2 phase this phase lasts for
approximately 2 to 5 hours during G2 the
cell continues to grow and prepares for
division by reorganizing its organel and
cytoskeleton this phase is characterized
by further synthesis of proteins
required for mitosis at the end of G2
phase and before entering the the
mitosis there is a checkpoint known as
G2 checkpoint G2 checkpoint is a cell
division checkpoint that occurs during
the G2 phase which checks for DNA damage
and completeness of DNA replication it
facilitates the initiation of mitosis
through phosphorilation of various
proteins for example histones regulat
synchronized cell division mediated by
mitosis promoting factor that cycl B
cdk1 complex M phase in the M phase the
DNA condenses to form visible pairs of
sister chromatids attached at the centrr
they're subsequently separated and moved
to opposite poles of the cell after the
M phase the cell splits into two
daughter cells in a process called cyto
Kinesis karyotypes are obtained from
cells in the M phase mitosis is the
final step in cellular division prior to
the two daughter cells separating from
one another and it has four stages stage
one prophase profase is a stage during
which the DNA condenses into 46 pairs of
sister chromatids linked together at the
center by a centrr centrr keep the
sister chromatids together until it is
time to separate and ensure that each
daughter cell gets the right sister
chromatids without any duplicates or
loss
centrosome separation the centrosome is
the point of origin of the mitotic
spindle it consists of two centrioles
and a surrounding Matrix from which the
microtubules emerge prophase is a stage
of formation of the mitotic spindle
stage two metaphase metaphase is a stage
during which all the sister chromatid
pairs align at the center of the cell
and prepare for separation this is a
crucial step in which checks are made to
make sure that all the chromosomes are
attached to the mitotic Centrum mirors
in such a way that when they are pulled
apart the sister chromatids are evenly
split between the two new cells clinical
link Vin Christen a chemotherapy drug
prevents the formation of microtubules
that attach to the centrom in mitosis M
checkpoint spindle checkpoint it is a
third checkpoint between metaphase and
anaphase in mitosis this checkpoint
ensures correct alignment of the
chromosomes and sister chromatids at the
equatorial plane before the separation
of sister chromatids stage three
anaphase in anaphase the sister
chromatid start separating and moving to
the opposite poles of the cell stage
four tase in tase the cell starts
physically dividing into two it is
characterized by DEC condensation of the
chromosomes disintegration of the
mitotic spindle formation of a new
nuclear membrane cell bodies division at
the equatorial plane ribosomal RNA
synthesis clinical link proper
functioning of the mitotic spindle is a
prerequisite for chromosome
Transportation inhibition with spindle
poisons leads to arrest of mitosis and
cation of cell division spindle poisons
includ cesin as well as vinka alkaloids
and taxanes which inhibits microtubular
polymerization cytokinesis it is usually
marked by formation of a Clift in the
cell membrane as the mother cell starts
dividing into two daughter cells coming
to the G not phase it is also known as
the resting phase during the G not phase
the cell exits the cell cycle and
becomes quiescent until it receives
external stimuli in the form of growth
factors to start replicating again at
which time it will enter back into the
cell cycle at the G1 stage growth
factors are of different forms including
hormones and proximity signals from
nearby cells these ultimately initiate a
signaling Cascade inside the cell that
activates the proteins necessary for
initiation of cell division the amount
of time a cell spends in G not phase is
dependent on the cell type mature
neurons spend most if not all of their
lifespan in G not phase while cells that
produce the intestinal lining May rarely
or never enter G not
phase
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