Download Mitosis (Karyokinesis) On a separate quiz fill in the blanks from the

Student Name: ______________________________________________Class: __________ Date:
Mitosis (Karyokinesis)
[Quote / paraphrased from page 205: 2017. Vodopich, D.D.,
and Moore, R. BIOL 1406, Biology Laboratory Manual:
Biological Investigations, South Texas College. McGrawHill Education LLC. Source of figure: https://www.pinterest.com
Terminology note: The terms ‘stages’ and ‘phases’ are
often used differently by different authorities to name
the subdivisions of the cell cycle and of the part of the
cell cycle called mitosis. We will follow your lab
manual, which calls the subdivisions in the cell cycle for
STAGES, and the subdivision of the mitosis as PHASES.
On a separate quiz fill in the blanks from the text below:
• Cells grow and usually replicate (divide into two new cells) during their life, in a repeating set of
events called the cell cycle. Cells spend most of the time in what is called Interphase. In
preparation for the division (into two new cells called daughter cells), the chromosome material
(DNA) was duplicated during Interphase in the parental cell -- chromosome were ‘duplicated’ to
consist of identical parts called chromatids.
• When a Eukaryotic cell is ready, it undergoes the division phase called Mitosis (or M phase, or
Karyokinesis). Mitosis is the exactly equal division of the nuclear material (the chromosomes), so
that each new daughter cell formed from the parental cell will have the same exact duplicated set of
the genetic material (chromosomes; DNA). Immediately following the nuclear division the rest of
the cell divides in a process called cytokinesis (the cytoplasm and the organelles are not
necessarily divided into equal halves as the chromosomes).
• Each of the two new nuclei formed in the daughter cells has a full set of chromosomes containing
a copy of all the genetic information (DNA) for the organisms. The material is now ‘unduplicated’
since the identical chromatids were separated during the division.
• A prokaryotic cell lacks a nucleus and does not undergo mitosis. Instead it replicates the
chromosomes in the cytoplasm and then divide in half during a process called binary fission.
• Mitosis (karyokinesis) and cytokinesis are important because they provide a mechanism for
orderly growth of living organisms.
The Cell Cycle
• The cell cycle begins with the formation of a new cell and ends with replication of that cell. It can
be divided into the following phases (the first three are part of the Interphase):
G1: Gap 1. Proteins and other molecules are formed for the metabolism of the cell.
S: Synthesis. The DNA, composing the chromosomes, is duplicated
G2: Gap 2. Material necessary for the division (mitosis) are synthesized.
M: Mitosis. The DNA (chromosomes) are divided into two exact equal parts
• Cytokinesis occur at the end of the M phase.
Mitosis (Karyokinesis)
• Mitosis is the division of the nuclear material (the chromosomes) in the parental cell. In
preparation for the cytokinesis to form two daughter cells with identical DNA. Note that when the
cell enters prophase the chromosomes are ‘duplicated’. The phases of mitosis are (we will adhere
to the 4 phases model):
Student Name: ______________________________________________Class: __________ Date:
Prophase:
The chromosomes condense (the chromatids shortens and become visible), the
nucleoli disappear, the nuclear membrane disappears, and spindle fiber (microtubules) are formed
(which will help the chromosome move in the next phase).
Metaphase:
The chromosomes line up in the middle of the cell (called a ‘metaphase plate), with
help of the newly formed spindle fibers. These fibers ensure that the DNA is placed in pairs so that
each new cell will get one copy of each chromosome.
Anaphase: The chromosomes separate, dividing evenly to both sides of the cell.
Telophase: The steps in prophase occur in reverse. The chromosomes decondense (the
chromatids grow longer), the nucleoli reappear, the nuclear membrane reappears, the spindle fibers
disappear.
• Cytokinesis occur at the end of telophase.
• The cell division is now complete and two new cells have been formed -- with the DNA
‘unduplicated’ and identical. Note that the duplicated chromosomes now have split (and separated
in anaphase). Each new daughter cell has received identical halves of the previously duplicated
chromosomes.
• Class activity: You will observed the roots of longitudinal sections of onion
(Allium) roots that have been preserved in the state of growth they were in when
alive. You will locate and identify each mitosis phase using a microscope at high
magnification (do not use the oil immersion lens).
1.
First review what characteristics to look at in the different phases. Name each
phase in the table below and describe what you would expect to see (SEE LIST ABOVE):
Phase
Distinguishing characteristic(s)
_______________ ____________________________________
____________________________________
_______________ ____________________________________
____________________________________
_______________ ____________________________________
_______________ ____________________________________
____________________________________
Note: Some textbooks distinguish between ‘prometaphase’ and ‘metaphase’. It can be difficult to
distinguish between these artificial subdivisions. We follow the four phase model here.
Student Name: ______________________________________________Class: __________ Date:
2. Obtain a slide with Allium.
(Make sure it is a slide with the root tip(s) clearly visible. In some
old slides they have faded...) Focus on the onion root tip using proper focusing procedure
(start with scanner, then move to low magnification, then to high magnification. Do NOT use the coarse
focus know at high magnification).
3.
When the cells were alive, growth occurred when they divided, so the root tips
should have several cells in process of cell division. Note that most cells are in some
part of Interphase. First view the root tip and search for organized block of cells
where nuclei are plainly visible.
4. Move the slide around until you find a good spot that shows the cells in various
stages of mitosis (most activity would be occurring near the tip of the root, and remember that in
the microscope the root would appear up-side-down).
Search for examples of all phases of mitosis
(see figure on separate handout).
Drawings activity 1:
Draw the mitosis phases on the provided handout(s), as
you see them in the microscope.
Drawings activity 2: Use the provided figure of the cell walls of four empty
cells. Draw the cells with four (4) chromosomes in each of the mitosis phases. (Label
the cell wall and the cell plate.)
----------------------------------------------------------------------------------------------------------------------Items to submit for a grade:
1. Fill-in-the blanks quiz.
2. Drawing activity 1 handout(s).
3. Drawing activity 2 handout.
You do not have to submit the table on the second page, but you are allowed to use it at the lab
practicum, so you are advised to fill it in carefully...
----------------------------------------------------------------------------------------------------------------------The lab ends with this figure, which might be helpful. Source: http://creationwiki.org/Mitosis
Student Name: ______________________________________________Class: __________ Date:
Fill-in-the-blanks-quiz: Mitosis (Karyokinesis)
• Cells grow and usually replicate (divide into two new cells) during their life, in a repeating set of
events called the _________________ _________________. Cells spend most of the time in what
is called _________________. In preparation for the division (into two new cells called daughter
cells), the chromosome material (DNA) was _________________ during Interphase in the parental
cell -- chromosome were ‘duplicated’ to consist of identical parts called chromatids.
• When a Eukaryotic cell is ready, it undergoes the division phase called _________________ (or
M phase, or Karyokinesis). Mitosis is the exactly equal division of the _________________
material (the chromosomes), so that each new daughter cell formed from the parental cell will have
the same _________________ duplicated set of the genetic material (chromosomes; DNA).
Immediately following the nuclear division the rest of the cell divides in a process called
_________________ (the cytoplasm and the organelles are not necessarily divided into equal
halves as the chromosomes).
• Each of the two new nuclei formed in the _________________ cells has a full set of
chromosomes containing a copy of all the genetic information (DNA) for the organisms. The
material is now ‘_________________’ since the identical chromatids were separated during the
division.
• A prokaryotic cell lacks a nucleus and does not undergo mitosis. Instead it replicates the
chromosomes in the cytoplasm and then divide in half during a process called binary fission.
• Mitosis (_________________) and _________________ are important because they provide a
mechanism for orderly growth of living organisms.
The Cell Cycle
• The cell cycle begins with the formation of a new cell and ends with replication of that cell. It can
be divided into the following phases:
G1, S , G2, M...
Mitosis (Karyokinesis)
• Mitosis is the division of the _________________ material (the _________________) in the
parental cell. In preparation for the cytokinesis to form _________________ daughter cells with
_________________ DNA. Note that when the cell enters prophase the chromosomes are
‘duplicated’. The phases of mitosis are:
Prophase, Metaphase, Anaphase, Telophase.
• Cytokinesis occur at the end of telophase.
• The cell division is now complete and _________________ new cells have been formed -- with
the DNA ‘unduplicated’ and _________________. Note that the duplicated chromosomes now
have split (and separated in anaphase). Each new daughter cell has received identical halves of
the previously _________________ chromosomes.