Biology Lab || Mitosis
Summary
TLDRThis lab explores the stages of chicken embryo development through mitosis, where a single cell becomes a multicellular organism. The process involves five phases: prophase, prometaphase, metaphase, anaphase, and telophase. The video demonstrates preparing a microscope slide with onion root tip cells to observe these stages. Techniques include soaking in hydrochloric acid and car noise solution, staining with toluidine blue, and examining under a microscope to witness cells in various phases, illustrating the fundamental process of growth and development in both plants and animals.
Takeaways
- π£ The process of mitosis is how a single fertilized cell becomes a multicellular organism, such as a chicken, through cell division.
- π¬ Mitosis involves five phases: prophase, prometaphase, metaphase, anaphase, and telophase, each with distinct cellular changes.
- 𧬠During mitosis, each daughter cell receives an identical set of chromosomes to the parent cell, maintaining genetic consistency.
- π§ The lab focuses on examining onion root tip cells, which are actively dividing and can display all stages of mitosis.
- π± The onion's apical meristem is the region of active growth and cell division, ideal for observing mitosis.
- π§ͺ The preparation of the sample involves soaking in hydrochloric acid to break down cell walls and then in Carnoy's solution to fix the cells.
- π A thin section of the root tip is prepared for microscopic examination to observe cells in various stages of mitosis.
- π Toluidine blue dye is used to stain DNA, enhancing visibility of chromosomes during microscopic examination.
- π¬ The microscope is used to first observe the sample under low power to identify the terminal end and then under high power to see cells in detail.
- π During interphase, the nucleus appears cloudy blue due to DNA staining, but chromosomes are not yet condensed and visible.
- 𧬠Prophase is marked by chromosome condensation, making them visible as X-shaped structures under the microscope.
- π Prometaphase involves the dissolution of the nuclear membrane and the formation of the spindle apparatus by microtubules.
- π Metaphase lines up the chromosomes along the cell's equator, preparing for separation in anaphase.
- π Anaphase sees the separation of sister chromatids and their movement toward opposite poles of the cell.
- π‘οΈ Telophase involves the formation of new nuclear membranes around the separated chromosomes, leading to cell division.
- πΏ Mitosis is crucial for the growth and development of organisms, including plants like onions and humans.
Q & A
What is the main focus of the lab described in the script?
-The main focus of the lab is to examine the stages of mitosis in the development of a chicken embryo and to prepare and observe a microscope slide containing a sample of onion cells in various phases of mitosis.
How does a single fertilized cell become a multicellular organism through mitosis?
-A single fertilized cell becomes a multicellular organism through mitosis by dividing to form two daughter cells, each with the same number of chromosomes as the parent cell, ensuring genetic continuity.
What are the five phases of mitosis mentioned in the script?
-The five phases of mitosis are prophase, prometaphase, metaphase, anaphase, and telophase.
Why is the onion root tip used for observing cells in mitosis?
-The onion root tip is used because the cells in the apical meristem are actively growing and dividing, providing a rich sample to observe various phases of mitosis.
What is the purpose of soaking the sample in hydrochloric acid during the preparation process?
-The purpose of soaking the sample in hydrochloric acid is to break down the plant's hard cell walls, making it easier to observe the cells under a microscope.
What is a tissue fixative and why is it used in the lab?
-A tissue fixative is a solution that stops any chemical or biological reactions, preserving the sample for longer use. It is used to maintain the cells' state for examination.
What is the role of the toluidine blue dye in the lab?
-Toluidine blue is a dye that stains the DNA, making it more visible under a microscope by enhancing the contrast of the cell's nucleus and chromosomes.
How is the sample prepared for examination under a microscope?
-The sample is prepared by placing it on a microscope slide, adding toluidine blue dye, allowing it to soak for two minutes, blotting excess dye, adding water, and covering it with a glass coverslip to prevent air bubbles.
What is the significance of ensuring the cells are in a single layer under the coverslip?
-Ensuring the cells are in a single layer allows light to pass through for clear observation under the microscope, and it prevents the cells from being destroyed or the coverslip from cracking.
What happens during prophase of mitosis as described in the script?
-During prophase, each replicated chromosome undergoes condensation, becoming shorter and thicker, and is visible under a microscope as it resembles a letter X.
Can you describe the process of replication mentioned in the script?
-Replication is the process by which a chromosome produces a duplicate of itself, preparing the cell for the first phase of mitosis, prophase.
Outlines
π¬ Mitosis in Chicken Embryo Development
This paragraph introduces the process of mitosis, which is fundamental to the development of a chicken embryo from a single fertilized cell into a multicellular organism. It explains the five phases of mitosis: prophase, prometaphase, metaphase, anaphase, and telophase. The lab activity involves preparing a microscope slide with onion cells to observe these phases. The onion's apical meristem, where cells are actively dividing, is the source of the sample. The preparation process includes soaking in hydrochloric acid to break down cell walls, followed by treatment with Carnoy's fixative to halt reactions. A thin section of the root tip is stained with toluidine blue to visualize DNA and then mounted on a microscope slide for examination.
πΏ Observing Mitosis Phases in Onion Root Cells
The second paragraph delves into the observation of mitosis stages in onion root tip cells under a microscope. It starts with an overview of cells in interphase, where the nucleus appears cloudy blue due to DNA staining. As cells progress to prophase, chromosomes condense and become visible. Prometaphase sees the dissolution of the nuclear membrane and the formation of the spindle by microtubules. In metaphase, chromosomes align at the cell's equator, and anaphase involves the separation and movement of chromosomes toward cell poles. Finally, telophase is characterized by the formation of new nuclear membranes and the emergence of two daughter cells. The paragraph concludes by emphasizing the importance of mitosis in growth and development, both in plants and humans, and hints at the next lab's focus on plant genetics.
Mindmap
Keywords
π‘Mitosis
π‘Prophase
π‘Prometaphase
π‘Metaphase
π‘Anaphase
π‘Telophase
π‘Apical Meristem
π‘Toluidine Blue
π‘Interphase
π‘Chromosome Replication
π‘Microtubules
Highlights
The process of mitosis allows a single fertilized cell to develop into a multicellular organism, such as a chicken.
Mitosis involves five phases: prophase, prometaphase, metaphase, anaphase, and telophase.
The apical meristem of an onion root tip is an area of active cell growth and division.
Samples from the onion root tip are preserved in an alcohol solution for lab examination.
Hydrochloric acid is used to break down plant cell walls in preparation for microscopy.
A tissue fixative, such as Carnoy solution, is used to stop chemical and biological reactions for sample preservation.
Identifying the terminal end of the onion root tip is crucial for selecting the appropriate sample for examination.
A section of the root tip is sliced off for examination, using a magnifying glass to assist in identification.
Toluidine blue dye is applied to stain DNA, enhancing visibility under the microscope.
Proper preparation of the microscope slide is essential to avoid air bubbles and ensure a single layer of cells.
Low-power microscopy reveals cells in interphase, before mitosis begins.
High-power microscopy allows for the observation of cells in various stages of mitosis.
During interphase, the nucleus appears cloudy blue due to DNA staining, but chromosomes are not yet visible.
Chromosome replication occurs near the end of interphase, preparing the cell for mitosis.
Prophase is characterized by chromosome condensation, making them visible under the microscope.
Prometaphase involves the dissolution of the nuclear membrane and the formation of the mitotic spindle.
Metaphase is when chromosomes line up at the cell's equator, facilitated by microtubules.
Anaphase is marked by the separation of replicated chromosomes moving toward cell poles.
In telophase, new nuclear membranes form around the chromosomes at the cell poles.
The final stage of mitosis is the separation of the two daughter cells, each entering a new interphase.
Mitosis is fundamental to the growth and development of organisms, including plants and humans.
Transcripts
[Music]
in an earlier lab we examine the stages
in the development of a chicken embryo
how did one fertilized cell become a
multicellular chicken the answer is
through the process of mitosis during
mitosis a parent cell divides to form
two daughter cells each daughter cell is
a smaller copy of the parent cell with
the same number of chromosomes as the
parent cell during mitosis a cell goes
through five phases prophase
prometaphase metaphase anaphase and
telophase in this lab we will prepare a
microscope slide containing a sample of
onion cells and examine the cells in
each phase of mitosis the bulb of the
onion is a type of stem that grows
underground the bulb produces shoots
which sprout from the top of the bulb
and roots which descend from the bottom
of the bulb the region near the tip of
an onion root is called the apical
meristem the cells in the apical
meristem were actively growing and
dividing when the plant was alive so we
should be able to see cells in the
various phases of mitosis when the root
tip is examined under a microscope tiny
samples have been cut from the tips of
onion roots and preserved in an alcohol
solution we will use one of the samples
in this lab several steps are needed to
prepare the sample for viewing under the
microscope to break down the plants hard
cell walls the sample must be soaked in
hydrochloric acid for four minutes after
four minutes we remove the sample from
the hydrochloric acid and transfer it to
a container with a tissue fixative a
tissue fixative is a solution that will
stop any chemical or biological
reactions that might be occurring so
that a bile
sample can be preserved for longer use
the fixative we are using is car noise
solution the onion root tip must soak in
car noise solution for four minutes
after the sample soaks for four minutes
we transfer it to a clean microscope
slide we need to examine the onion root
tip to determine which end is the
terminal end the terminal end of this
sample is the rounded end since the root
is so thin a magnifying glass will help
us identify the terminal end once we
have identified the terminal end of the
root tip we hold it down with the
forceps and use a scalpel to slice off a
section about two millimeters from the
terminal end this is the sample we will
examine the rest of the root tip can be
discarded we place the sample on the
microscope slide and add two drops of
toluidine blue toluidine blue is a dye
that stains the DNA in order to see it
more clearly the toluidine blue needs to
remain undisturbed for two minutes
once the toluidine blue has had time to
soak into the cells of the onion root
tip we blot the excess dye with a paper
towel taking care not to touch the
sample with the paper towel we've lot as
much of the dye as possible from the
edge of the drop using a pipette we add
two drops of water to the sample and
cover it with a glass coverslip to keep
from trapping air bubbles under the
coverslip we place one edge of the
coverslip against the slide and gently
lower the cover slip into place the
cells of the sample must be in a single
layer to allow light to pass through to
make certain the cells are in a single
layer we place a paper towel over the
coverslip and then slowly butt
firmly press down on the coverslip
we must not twist or turn the sample
while pressing down on the coverslip
or the cells may be destroyed and we
must not press too hard or we could
crack the coverslip or the microscope
slide now we are ready to examine our
sample under the microscope to see a
large portion of the sample we examine
it under the low-power objective most of
the cells will be an interface which is
the stage of development before mitosis
begins to see details of individual
cells we will switch to the highest
power objective in this view cells in
several phases are visible during
interphase the nucleus of the cell
appears to be a cloudy blue the
toluidine blue has stained the DNA but
the individual chromosomes are not yet
visible because the chromosomes are
spread out in long intertwined strands
near the end of interphase each
chromosome in the cell's nucleus
undergoes replication replication is the
process by which a chromosome produces a
duplicate of itself
now that the chromosomes have replicated
the cell is ready to begin the first
phase of mitosis called prophase during
prophase each replicated chromosome
undergoes condensation condensation is
the process in which a replicated
chromosome twists around itself to
become shorter and thicker at this point
the replicated chromosomes are thick
enough to be visible under a microscope
each chromosome looks like a letter X
but since the chromosomes are tangled
together within the nucleus it is
difficult to see their shapes the next
phase of mitosis is prometaphase during
prometaphase the cell's nuclear membrane
dissolves notice that the shapes of the
rep
kated chromosomes are becoming easier to
distinguish after the nuclear membrane
dissolves hollow protein tubes called
microtubules extend across the cell and
attach to the replicated chromosomes the
microtubules begin to form an
oval-shaped grid or spindle which
stretches across the cell from pole to
pole the next phase of mitosis is called
metaphase during metaphase the
microtubules cause the replicated
chromosomes to line up along the cell's
equator after metaphase a cell enters
the next phase of mitosis called
anaphase during anaphase the replicated
chromosomes split apart again into
individual chromosomes and the
chromosomes begin to move toward the
poles of the cell once all the
chromosomes cluster together near the
poles of the cell the cell begins the
last phase of mitosis which is called
telophase during telophase the cell
forms a separate nuclear membrane around
each cluster of chromosomes near the
poles as soon as the new nuclear
membranes form during telophase the cell
separates into two separate daughter
cells after the two daughter cells have
been formed each cell enters interphase
and prepares to continue the process of
mitosis through the process of mitosis
an onion is able to grow and develop
into a mature plant the same process of
mitosis enables our bodies to grow and
develop into mature adults in our next
lab we will explore genetics in plants
at this time proceed with the
corresponding activities
you
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