Cell Cycle (Mitosis)
Summary
TLDRThe video provides a detailed overview of the cell cycle, focusing on mitosis. It explains key stages, such as prophase, metaphase, anaphase, and telophase, with emphasis on chromosome duplication, alignment, and separation. Viewers are guided through how chromosomes and chromatids behave during these phases, and how centrosomes play a crucial role in cell division. The video also touches on cytokinesis, the final step where the cell divides into two daughter cells. The importance of understanding chromosome numbers throughout mitosis is highlighted for a clearer grasp of the process.
Takeaways
- 🧬 The cell cycle consists of two main phases: Interphase and M Phase.
- 🔬 Mitosis occurs during M Phase and is the process where a cell divides to produce two daughter cells.
- 🔄 In Prophase, duplicated chromosomes become visible, and the centrosomes form the mitotic spindle.
- 📏 During Prophase, the cell has 46 chromosomes (23 pairs) with 92 chromatids.
- 🎯 In Prometaphase, microtubules attach to chromosomes at the centromeres, moving them towards the spindle equator.
- 🧲 In Metaphase, chromosomes align at the metaphase plate, and the centrosomes are on opposite sides of the cell.
- 🔗 Anaphase involves the separation of chromatids, with each chromatid pulled to opposite spindle poles.
- ⚖️ In Anaphase, the cell now has 92 chromosomes and 92 chromatids as chromatids are split into separate chromosomes.
- 🌀 Telophase sees chromosomes cluster at opposite poles, nuclear envelopes reform, and organelles reassemble.
- ✂️ Cytokinesis is the final step of the M Phase, resulting in two daughter cells, each with 46 chromosomes and 46 chromatids.
Q & A
What are the two main phases of the cell cycle?
-The cell cycle consists of two main phases: interphase and the M phase. M phase includes mitosis, where cell division occurs.
What happens during prophase in mitosis?
-In prophase, the chromosomes condense and become visible. The centrosomes start forming the mitotic spindle, and the nuclear envelope begins to break down.
What is the role of the centromere during mitosis?
-The centromere is the region that holds duplicated chromosomes together. It plays a key role in chromosome separation by attaching to microtubules from the centrosomes.
How do the chromosomes behave in prometaphase?
-In prometaphase, the nuclear envelope fragments, allowing chromosomes to move freely. The chromosomes attach to the mitotic spindle via their kinetochores and begin to move toward the equator of the cell.
What happens during metaphase in mitosis?
-During metaphase, chromosomes align along the metaphase plate (equator of the cell). The centrosomes are positioned on opposite poles, and microtubules connect to the chromosomes, preparing them for separation.
What occurs in anaphase, and how do the chromosomes change?
-In anaphase, the centromeres split, and the chromatids are pulled apart by the microtubules toward opposite poles of the cell. Each chromatid becomes a separate chromosome, resulting in 92 chromosomes during this phase.
How does the cell prepare for division during telophase?
-During telophase, the chromosomes cluster at opposite poles of the cell, the nuclear envelope reassembles around each group of chromosomes, and the cell begins to reorganize its structures.
What is cytokinesis, and how does it differ from mitosis?
-Cytokinesis is the final step of the M phase, where the cell divides into two daughter cells. It is not part of mitosis itself, which is the division of the nucleus. Each daughter cell ends up with 46 chromosomes.
How many chromosomes and chromatids are present in a cell during metaphase?
-During metaphase, the cell has 46 chromosomes and 92 chromatids, as each chromosome consists of two chromatids.
What is the significance of understanding chromosome and chromatid numbers during mitosis?
-Understanding the number of chromosomes and chromatids at each stage of mitosis helps clarify the process of cell division, ensuring accurate replication and distribution of genetic material to daughter cells.
Outlines
🔬 Overview of the Cell Cycle and Mitosis
In this introduction, Armand Hassan explains the cell cycle, dividing it into two main phases: interphase and M-phase. The focus is on mitosis, a process within M-phase where a cell divides to produce two daughter cells. The first stage of mitosis, prophase, is described as a phase where duplicated chromosomes appear, and the centrosomes begin forming a mitotic spindle. The genetic material at this stage consists of 46 chromosomes or 23 pairs, with 92 chromatids. Prophase sees the condensation of chromosomal material into visible chromosomes, while the cytoskeleton disassembles and the nuclear envelope starts to degrade, allowing the chromosomes to be free. Prophase transitions into metaphase, which involves two stages, beginning with prometaphase.
🧬 Prometaphase and Metaphase Breakdown
The focus shifts to prometaphase, where the nuclear envelope fragments further, and the mitotic spindle begins to interact with the chromosomes. Microtubules extend from the centrosomes and attach to the centromeres of the chromosomes. These chromosomes move to the equator of the cell, known as the metaphase plate. In the late stage of metaphase, duplicated chromosomes align along this plate, and centrosomes are positioned at opposite poles of the cell. The genetic makeup remains unchanged from prophase, with 46 chromosomes and 92 chromatids, but the arrangement of chromosomes is crucial for the next phase, anaphase.
🧲 Anaphase: Separation of Chromatids
During anaphase, the centromeres holding the duplicated chromosomes split, allowing the chromatids to separate. The microtubules pull one chromatid toward each centrosome at the opposite poles of the cell. As a result, the 46 chromosomes and 92 chromatids present before anaphase now appear as 92 chromosomes (each chromatid now considered a chromosome). The spindle poles also move further apart in preparation for the final stages of mitosis. The explanation clarifies that the total genetic material of the cell remains the same but reorganized into two sets of chromosomes.
🧪 Telophase: Chromosome Clustering and Nuclear Reformation
Telophase, the final stage of mitosis, is characterized by the chromosomes clustering at opposite spindle poles, the reformation of the nuclear envelope, and the disassembly of the mitotic spindle. The genetic material is organized into two sets, each with 46 chromosomes and 46 chromatids per daughter cell. At this stage, the physical process of cell division is nearly complete, but the final step of the M-phase, cytokinesis, must occur for full division.
🔄 Cytokinesis and Conclusion of Mitosis
Cytokinesis, which follows telophase, is not part of mitosis but completes the M-phase. It involves the separation of the cytoplasm, resulting in two daughter cells, each with 46 chromosomes. The daughter cells can either enter the cell arrest phase or proceed back to interphase for future cell cycles. This marks the conclusion of the division process. The video wraps up with a recap of the entire cell cycle, emphasizing the importance of chromosome and chromatid numbers during each phase for understanding mitosis.
Mindmap
Keywords
💡Interphase
💡Mitosis
💡Chromosome
💡Chromatid
💡Centrosome
💡Mitotic spindle
💡Centromere
💡Anaphase
💡Metaphase
💡Cytokinesis
Highlights
The cell cycle consists of two main phases: interphase and M phase, with mitosis occurring within the M phase.
Mitosis is the process where a cell divides to produce two identical daughter cells.
The first phase of mitosis is prophase, where centrosomes begin forming the mitotic spindle.
In prophase, the genetic material condenses into visible chromosomes, and the nuclear envelope starts to degrade.
Prometaphase follows prophase, where the mitotic spindle connects to the centromeres of chromosomes.
In metaphase, duplicated chromosomes align on the metaphase plate at the center of the cell.
During metaphase, the chromosomes are connected to the centrosomes at opposite poles of the cell.
Anaphase begins when the centrosomes pull the duplicated chromosomes apart, separating chromatids to opposite sides.
In anaphase, each chromatid becomes a chromosome, resulting in 92 chromosomes and 92 chromatids in total.
Telophase is the phase where the chromosomes cluster at opposite poles and a new nuclear envelope forms around them.
At the end of telophase, the cell contains 92 chromosomes and 92 chromatids, distributed between the spindle poles.
Cytokinesis, although not part of mitosis, completes the M phase by dividing the cell into two daughter cells.
Each daughter cell will have 46 chromosomes or 23 pairs after cytokinesis, and each chromosome has one chromatid.
Following cytokinesis, cells can either enter a resting phase or proceed through the interphase again before another mitotic cycle.
Mitosis can be defined as the process by which duplicated chromosomes are separated into two nuclei, facilitating cell division.
Transcripts
Armand Hassan biology and Medicine
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huran just recapping the cell cycle
consists of two main phases the
interphase and the
mhase
mitosis uh occurs within the mphase and
mitosis is the process where a cell will
divide to produced two do
cells the first phase of mitosis is
prophase here we have a cell with um the
duplicated
chromosomes um just recapping what we
see in prophase we have the centrosomes
those important structures for cell
division they begin forming a what's
called mitotic
spindle looking at the genetic material
of the cell during profan
it will have
46 chromosomes or 23 pairs of
chromosomes with 92 chromatids because
one chromosome has two chromatids this
structure in the middle here holding the
duplicated chromosome together is known
as a central mirror and it is important
to know
centrom and croome sounds familiar but
don't get mixed
up so during prophase the chromal
material condenses to form a compact
mitotic chromosome so it becomes visible
the chromosomes essentially the
cytoskeleton is then disassembled and
mitotic uh spindle is
assembled so the centrosomes form a
mitotic spindle the nuclear envelope is
also dispersed so the N the the nucleus
membrane essentially uh starts uh starts
degrading to allow these chromosomes to
be free you can say now prophase will
then enter
metaphase the cell in prophase will then
enter
metaphase metaphase itself has an early
stage and a late stage let's look at the
early stage first known as PR
metaphase here we have the the chrom
just in the
cytoplasm we have the centrosomes
remember forming the mitotic
spindle you will see in prometaphase
that the cell will still have the
fragments of the nuclear envelope that
was uh
degrading the centrosomes itself will
form the mitotic spindle by shooting out
these microt tubules that will connect
to the central mirror of the chromosome
the middle part of the duplicated
chromosome so during prometaphase the
chromosomal microtubules attach to
kinetic cores of the
chromosomes chromosomes are then moved
to the spindle equator which is
essentially the spindle equator is the
middle of the cell the equator of the
cell looking at the genetic material of
this cell during prometaphase it will
still have 46 chromosomes and 92
chromatids the the cell in prometaphase
will then enter metaphase the late stage
where the chromosomes the duplicated
chromosome will will align on the
equator the Centra zomes are on opposite
side of each other in the cell and they
form a massive mitotic spindle with the
microtubules in metaphase so the
chromosomes are aligned along the
metaphase plate which is the equator
here this is a metaphase plate
the duplicated chromones that are
aligned on the metaphase plate will then
be
attached by the Chrome aboral
microtubules um at both
poles what this means is that the Centra
the Centro zomes on each of the poles
will have
microtubules um attaching to the same uh
chromosomes essentially
and so if we look at the genetic
material of the of the cell during the
metaphase it will still have 46
chromosomes with 92 chromatids of
course the cell in metaphase will then
enter
anaphase now this might sound a bit
confusing but I hope you can follow this
so in anaphase essentially the
centrosomes with the microtubular
will pull the
duplicated uh chromosomes apart like so
and so um so one chromatid will go
towards one uh s uh centrosome and the
other will go to the other centrone
because it's being pulled
apart and so in anaphase the Centras
which hold the duplicated chromosomes
together will split and the chromatids
will separate
the chromosomes will then move to
opposite spindle poles the
chromatids and then the spindle poles
will move further apart ready for
division so just recapping this is the
centrosome and this is the Centro Mia
which previously held the duplicated
Chrome
zone so let's look at the process of
what happens with the genetic material
during
anaphase so before anaphase we had
remember a duplicated chromosomes two
chromatids per one chromosome so in
total we had 46 chromosomes and 92
chromatids during anaphase the
microtubules with the centrosomes will
split this apart essentially forming two
chromosomes each with one
chromatid so therefore in total we would
see 92 chromosomes and 92 chromatids in
this
cell I hope this makes
sense now the cell in anaphase will then
enter the last phase of mitosis which is
cello
phase cello phase is essentially when we
see the centrosome with the microt
tubules pulling the chromosomes closer
to each of their poles and then we also
see a membrane forming around
it and so in chillo Phase um what we see
is the chromosomes are clustering at
opposite spindle
poles like so the chromosomes become
dispersed the nuclear envelope will
assemble and the organel will
reform and so this is our nuclear
envelope which is
reassembling
essentially so now if we were look to
look at the the genetic material of the
cell during
Chase it would have this would represent
one
chromosome which has one
chromatid and therefore the cell would
have in total 92 chromosomes and 92
chromatids the cell will then enter
um the last phase of mphase not mitosis
but the last phase of M phase known as
cyto canis now cyto canis is not part of
mitosis but it is part of mphase and it
is essentially the separation of um the
cell into two daughter cells and
therefore each of these um daughter
cells will have
46 chromosomes each or 23 pairs of
chromosomes each and of course one
chromosome will have one chromatid so it
will have 46
chromatids and this is because remember
the cell in cello phase had 92
chromosomes so if this cell with 92
chromosomes divide it will have 46 on
one daughter cell and another 46 in the
other
following cyto canis these cells can
enter the cell arrest phase or it can
enter the whole interphase and then
enter mitosis again after a while or
after some
time so now mitosis can be defined as
the process um by which duplicated
chromosomes separate into two
nuclei and this is essentially
the uh division
process hope you enjoyed this video on
the cell cycle oh we looked at the
interphase and we looked at mitosis in
quite detail it's important to know the
number of chromosomes and chromatids in
each of these steps to understand what
is actually
happening anyway I hope you enjoy this
video thank you
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