Lesson on cell mitosis

Lesson On Cell Mitosis

G.E.D. Studies.G.E.D. Studies.

New Creation Bible Church. 2011-12. New Creation Bible Church. 2011-12.

Instructor: Joseph D. Rhodes, B.S. Ed., M.A. Instructor: Joseph D. Rhodes, B.S. Ed., M.A. Week 3. April 12 & 15Week 3. April 12 & 15thth, 2011., 2011.



A A eukaryote organism eukaryote organism is oneis one whose cells contain complex whose cells contain complex structures enclosed within its membranes. The process of structures enclosed within its membranes. The process of mitosismitosis in eukararyotic cells is where the cell initiates a in eukararyotic cells is where the cell initiates a division or separation of the division or separation of the chromosomes chromosomes in its cell nucleus in its cell nucleus into two identical sets of two nuclei. This process acts by a into two identical sets of two nuclei. This process acts by a previous set of coded instructions. Then this part of the previous set of coded instructions. Then this part of the process is generally followed by a full separation process in process is generally followed by a full separation process in the cell called the cell called cytokinesis cytokinesis which pulls apart not only the which pulls apart not only the nuclei, but thenuclei, but the cytoplasm, organellescytoplasm, organelles, and even the, and even the cell cell membranes membranes as well. The result: theas well. The result: the parent cellparent cell has mitosed has mitosed into twointo two daughter cells .daughter cells .


Mitosis and cytokinesis together define the mitotic (M) Mitosis and cytokinesis together define the mitotic (M) phase of the phase of the cell cyclecell cycle —the division of the parent cell into —the division of the parent cell into two daughter cells, genetically identical to each other and to two daughter cells, genetically identical to each other and to their parent cell. This accounts for approximately 10% of the their parent cell. This accounts for approximately 10% of the total cell cycle. Mitosis occurs only in total cell cycle. Mitosis occurs only in eukaryotic cellseukaryotic cells and and the process varies in different species. Various kinds of cells the process varies in different species. Various kinds of cells have different internal molecular chemical codes which have different internal molecular chemical codes which starts and stops this process and regulates its steps. starts and stops this process and regulates its steps.

For now, just remember that during For now, just remember that during mitosis mitosis the the chromosomes divide into two sets within the cell nucleus !chromosomes divide into two sets within the cell nucleus !


Two Examples of Two Examples of MitosisMitosis

Animal cells undergo an "open" mitosis, where the Animal cells undergo an "open" mitosis, where the nuclear envelope breaks down before the chromosomes nuclear envelope breaks down before the chromosomes separate, whileseparate, while some fungi such assome fungi such as Aspergillus nidulansAspergillus nidulans and and Saccharomyces cerevisiaeSaccharomyces cerevisiae ( (yeastyeast) undergo a special ) undergo a special "closed" mitosis, where chromosomes divide within an "closed" mitosis, where chromosomes divide within an intact intact cell nucleuscell nucleus. . Prokaryotic cellsProkaryotic cells, which lack a true , which lack a true nucleus, divide by a process called nucleus, divide by a process called binary fusionbinary fusion..


Aspergillus nidulansAspergillus nidulans

http://en.wikipedia.org/wiki/File:Aspergillus_nidulans.jpg


Saccharomyces cerevisiaeSaccharomyces cerevisiae

http://en.wikipedia.org/wiki/File:S_cerevisiae_under_DIC_microscopy.jpg

http://en.wikipedia.org/wiki/File:20100911_232323_Yeast_Live.jpg


The process of mitosis is surprisingly fast and involves The process of mitosis is surprisingly fast and involves chemical alterations of large and highly complex protein chemical alterations of large and highly complex protein molecules. The sequence of events is divided into stages molecules. The sequence of events is divided into stages corresponding to the ending of one set of activities and the corresponding to the ending of one set of activities and the

beginning of the next. These stages arebeginning of the next. These stages are interphase, prophaseprophase,, (prometaphaseprometaphase), metaphasemetaphase, ana-ana-phasephase, and and telophasetelophase . During mitosis the pairs of . During mitosis the pairs of chromatidschromatids condense and attach to fibers that pull the condense and attach to fibers that pull the sister chromatidssister chromatids to opposite sides of the cell. The cell then to opposite sides of the cell. The cell then divides in cytokinesis, to generate two identical daughter divides in cytokinesis, to generate two identical daughter cellscells . .

Lesson On Cell Mitosis Errors in mitosis can either kill a cell throughErrors in mitosis can either kill a cell through apotosisapotosis or causeor cause mutationsmutations that may lead tothat may lead to cancercancer. . Because the complex arrangement of Because the complex arrangement of amino acids and bases of the protein chains in amino acids and bases of the protein chains in the nucleus even a slight modification by the nucleus even a slight modification by mutation can cause death or grotesque deformity mutation can cause death or grotesque deformity of a cell. The highly complex information in cells of a cell. The highly complex information in cells has been compared by some molecular bio-has been compared by some molecular bio-logists to a vast network of supercomputer logists to a vast network of supercomputer programs which would suffer immense damage if programs which would suffer immense damage if even one or two files are damaged or garbled. even one or two files are damaged or garbled. Some scientists (Intelligent design theorists) Some scientists (Intelligent design theorists) have argued that cells actually function by highly have argued that cells actually function by highly advanced engineering or design (something to advanced engineering or design (something to think about !) think about !)


Deoxyribonucleic acidDeoxyribonucleic acid

http://en.wikipedia.org/wiki/File:DNA_Structure%2BKey%2BLabelled.png


The structure of the DNAThe structure of the DNA ““double helix”: double helix”: The atoms in The atoms in the structure are colour - coded to identify eachthe structure are colour - coded to identify each elementelement, the , the spiralling backbone of the two strands is shown in orange spiralling backbone of the two strands is shown in orange and the detailed structure of two base pairs is shown in the and the detailed structure of two base pairs is shown in the bottom right of the previous picture representation .bottom right of the previous picture representation . Deoxyribonucleic AcidDeoxyribonucleic Acid, or , or DNA DNA is a nucleic acid that is a nucleic acid that contains all contains all the genetic information (codes of contains all contains all the genetic information (codes of life) that instructs the cells of all living organisms in their life) that instructs the cells of all living organisms in their development and functioning (with the exception of what development and functioning (with the exception of what are called are called RNA virusesRNA viruses). ). DNA DNA may be compared to set of may be compared to set of elaborate “blueprints” for living things; or, as some elaborate “blueprints” for living things; or, as some scientists have likened them, to a series of interlocking scientists have likened them, to a series of interlocking computer “codes” which operate the mechanisms of the computer “codes” which operate the mechanisms of the living cell. living cell.

Lesson On Cell Mitosis DNADNA contains the instructions needed to construct contains the instructions needed to construct other components of cells, such asother components of cells, such as proteinsproteins andand RNARNA moleculesmolecules. . The DNA segments that carry this genetic The DNA segments that carry this genetic information are calledinformation are called genesgenes, , but other DNA sequences but other DNA sequences have structural purposes, or are involved in regulating the have structural purposes, or are involved in regulating the use of this genetic information. use of this genetic information. (This is that of which all living (This is that of which all living things are made and gives them their unique characteristics !)things are made and gives them their unique characteristics !) DNA DNA is itself composed of long complex protein chains is itself composed of long complex protein chains called called polymerspolymers. These polymers themselves are composed . These polymers themselves are composed of smaller units known as of smaller units known as nucleotidesnucleotides.. These are medium- These are medium- sized molecules with “backbones” or frameworks made of sized molecules with “backbones” or frameworks made of sugarssugars and and phosphate groupsphosphate groups joined by joined by ester bondsester bonds. .


http://en.wikipedia.org/wiki/File:ADN_animation.gif


DNADNA has two strands that run in opposite directions to has two strands that run in opposite directions to each other and are therefore anti – parallel. Attached to each each other and are therefore anti – parallel. Attached to each sugar is one of four types of molecules called basessugar is one of four types of molecules called bases.. The The primary nucleobases are primary nucleobases are cytosine, guanine, adeninecytosine, guanine, adenine ( (DNADNA and and RNARNA),), thyminethymine (DNA) and (DNA) and uraciluracil (RNA), abbreviated as (RNA), abbreviated as C, C, G, A, TG, A, T, and , and UU, respectively. These amino acid bases are the , respectively. These amino acid bases are the foundation for the study of Genetics.foundation for the study of Genetics. It is the sequence of these four bases along the backbone It is the sequence of these four bases along the backbone that encodes information. This information is read using the that encodes information. This information is read using the genetic codegenetic code, which specifies the sequence of thewhich specifies the sequence of the amino amino acids within proteins. The code is read by copying stretches acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called of DNA into the related nucleic acid RNA, in a process called transcriptiontranscription.


Within cells,Within cells, DNADNA is organized into long structures calledis organized into long structures called chromosomeschromosomes. . These chromosomes are duplicated before These chromosomes are duplicated before cellscells divide, in a process called divide, in a process called DNA replicationDNA replication. . Eukaryotic Eukaryotic organismsorganisms (animals, plants, fungi, and protists) store most (animals, plants, fungi, and protists) store most of their DNA inside theof their DNA inside the cellcell nucleusnucleus and some of their DNA inand some of their DNA in organellesorganelles, such as , such as mitochondriamitochondria oror chloroplastchloroplastss.. In In contrast,contrast, prokaryotesprokaryotes ((bacteriabacteria andand archaeaarchaea) store their) store their DNADNA only in theonly in the cytoplasmcytoplasm. . Within the chromosomes,Within the chromosomes, chromatin proteins such asproteins such as histoneshistones compact and organize compact and organize DNADNA. These . These compact structures guide the interactions between compact structures guide the interactions between DNADNA and and other proteins, helping control which parts of the other proteins, helping control which parts of the DNADNA are are transcribed.transcribed.

http://en.wikipedia.org/wiki/Chromatin


http://en.wikipedia.org/wiki/File:DNA_chemical_structure.svg


http://en.wikipedia.org/wiki/File:GC_DNA_base_pair.svg

http://en.wikipedia.org/wiki/File:AT_DNA_base_pair.svg


Detailed Overview of MitosisDetailed Overview of Mitosis Essentially, Essentially, mitosis mitosis results in the transferring of the whole of results in the transferring of the whole of the parent cell’s genetic information (e.g., its the parent cell’s genetic information (e.g., its genomegenome) into two ) into two daughter cells. These new cells are identical to the parent cell. The daughter cells. These new cells are identical to the parent cell. The genome genome itself is made from the total number of itself is made from the total number of chromosomes –chromosomes –complexes of tightly coiled complexes of tightly coiled DNA strands – DNA strands – which, as we have said, which, as we have said, contain all the informational or programming codes (i.e., genetic contain all the informational or programming codes (i.e., genetic information) which are necessary for the cell to grow and function. information) which are necessary for the cell to grow and function. Yet, for this important biological process to work right, the parent Yet, for this important biological process to work right, the parent cell must make an cell must make an identical identical copy of each chromosome previous to copy of each chromosome previous to mitosis process. Technically, this is sometimes referred to as the mitosis process. Technically, this is sometimes referred to as the S-phaseS-phase of the of the interphaseinterphase ..


The InterphaseThe Interphase

An illustration of interphase in An illustration of interphase in Gray’s Anatomy.Gray’s Anatomy. The old and The old and newnew chromatinchromatin has not yet has not yet condensed, and the cell is still condensed, and the cell is still undergoing its normal functions.undergoing its normal functions.

http://en.wikipedia.org/wiki/File:Interphase.png


http://en.wikipedia.org/wiki/File:Interphase_and_part_of_Telophase_of_HT1080.PNG


Each chromosome now has an identical Each chromosome now has an identical copy of itself, and together the two are called copy of itself, and together the two are called homologus pairs. The homologus pairs are homologus pairs. The homologus pairs are held together by a specialized region of the held together by a specialized region of the chromosome known as thechromosome known as the centromerecentromere. . Each Each homologus pair is not considered a homologus pair is not considered a chromosome in itself, and a chromosome chromosome in itself, and a chromosome always contains 2 always contains 2 chromatidschromatids..


In most In most eukaryoteseukaryotes, the nuclear envelope which , the nuclear envelope which segregates the DNA from the segregates the DNA from the cytoplasmcytoplasm disassembles. The disassembles. The chromosomes align themselves in a line spanning the cell. chromosomes align themselves in a line spanning the cell. MicrotublesMicrotubles, essentially miniature strings, splay out from , essentially miniature strings, splay out from opposite ends of the cell and shorten, pulling apart the opposite ends of the cell and shorten, pulling apart the sister chromatids of each chromosome. As a matter of sister chromatids of each chromosome. As a matter of convention, each sister chromatid is now considered a convention, each sister chromatid is now considered a chromosome, so they are renamed to chromosome, so they are renamed to sister chromosomessister chromosomes. . As the cell elongates, corresponding sister chromosomes As the cell elongates, corresponding sister chromosomes are pulled toward opposite ends. A new nuclear envelope are pulled toward opposite ends. A new nuclear envelope forms around the separated sister chromosomes.forms around the separated sister chromosomes.


Phases of cell cycle and Phases of cell cycle and mitosismitosis((InterphaseInterphase and the Larger Cell Cycle) and the Larger Cell Cycle)

Compared to the much longer cell cycle, the Compared to the much longer cell cycle, the interphase interphase is a rel-is a rel-atively short period of time. But despite its brevity the atively short period of time. But despite its brevity the Interphase Interphase is is point where the cell prepares itself for point where the cell prepares itself for mitosismitosis.. Thus, Thus, interphase interphase is is actually distinct from actually distinct from mitosismitosis itself. itself. Interphase Interphase itself is defined by itself is defined by scientists as having three sub-phases or aspects: scientists as having three sub-phases or aspects: 1.1. G1 G1 (the first (the first Gap); Gap); 2. 2. S (Synthesis); S (Synthesis); andand 3. 3. G2 G2 (the second Gap). It is to be (the second Gap). It is to be observed that in all three phases, the cell grows because it observed that in all three phases, the cell grows because it produces produces proteinsproteins and and cytoplasmic organellescytoplasmic organelles. Only in the syn-. Only in the syn-thesis phase, however, are thesis phase, however, are chromosomes chromosomes replicated. replicated. Mitosis Mitosis then then falls as a short intermission in this larger cell cycle (see the next falls as a short intermission in this larger cell cycle (see the next

chart >>>> ). chart >>>> ).


All these phases in the interphase are highly regulated, mainly All these phases in the interphase are highly regulated, mainly via proteins. The phases follow one another in strict order and via proteins. The phases follow one another in strict order and there are "checkpoints" that gives the cell, the cues to proceed there are "checkpoints" that gives the cell, the cues to proceed from one phase to another.from one phase to another.

http://en.wikipedia.org/wiki/File:Cell_Cycle_2-2.svg


PreprophasePreprophase In plant cells only, prophase is preceded by a pre-prophase In plant cells only, prophase is preceded by a pre-prophase stage. Plant cells have many vacuoles, the nucleus has to migrate stage. Plant cells have many vacuoles, the nucleus has to migrate into the center of the cell beforeinto the center of the cell before mitosismitosis can begin. This is can begin. This is achieved through the formation of aachieved through the formation of a phragmosomephragmosome, , a transverse a transverse sheet of cytoplasm that bisects the cell along the future plane of sheet of cytoplasm that bisects the cell along the future plane of cell division. In addition tocell division. In addition to phragmosomephragmosome formation, preprophase formation, preprophase is characterized by the formation of a ring of microtubules andis characterized by the formation of a ring of microtubules and actinactin filaments (calledfilaments (called preprophase bandpreprophase band) underneath the plasma ) underneath the plasma membrane around the equatorial plane of the future mitoticmembrane around the equatorial plane of the future mitotic spindlespindle. . This band marks the position where the cell will This band marks the position where the cell will eventually divide. The cells of higher plants (such as the eventually divide. The cells of higher plants (such as the flowering flowering plantsplants) lack) lack centriolescentrioles; instead, microtubules form a spindle on ; instead, microtubules form a spindle on the surface of the nucleus and are then being organized into a the surface of the nucleus and are then being organized into a spindle by the chromosomes themselves, after the nuclear spindle by the chromosomes themselves, after the nuclear membrane breaks down.membrane breaks down. The preprophase band disappears The preprophase band disappears during nuclear envelope disassembly and spindle formation in during nuclear envelope disassembly and spindle formation in prometaphase. prometaphase.


Chart of MitosisChart of Mitosis

Prophase Prophase Prometaphase Prometaphase MetaphaseMetaphase

**Early Anaphase Early Anaphase TelophaseTelophase


Prophase:

The two round objects above the nucleus are the The two round objects above the nucleus are the centresomescentresomes. The . The chromatinchromatin has already condensed. has already condensed. ChromatinChromatin in the nucleus begins to condense and becomes in the nucleus begins to condense and becomes visible in the light microscope asvisible in the light microscope as chromosomeschromosomes. . The The nucleolus disappears.nucleolus disappears. CentriolesCentrioles begin moving to opposite begin moving to opposite ends of the cell and fibers extend from the centromeres. ends of the cell and fibers extend from the centromeres. Some fibers cross the cell to form the mitotic spindle. Some fibers cross the cell to form the mitotic spindle.


Prometaphase:

At this stage the At this stage the nuclear membranenuclear membrane has has degraded, and degraded, and microtubulesmicrotubules have invaded the have invaded the nuclear space. These nuclear space. These microtubulesmicrotubules can attach to can attach to kinetochoreskinetochores or they can interact with opposing or they can interact with opposing microtubulesmicrotubules. . Proteins attach to the Proteins attach to the centromerescentromeres creating the creating the kinetochoreskinetochores. . MicrotubulesMicrotubules attach at the attach at the kinetochoreskinetochores and the and the chromosomeschromosomes begin moving. begin moving.


Metaphase Metaphase ::

Spindle fibers align Spindle fibers align the chromosomesthe chromosomes along the along the middle of the cell nucleus. This line is referred to as the middle of the cell nucleus. This line is referred to as the metaphasemetaphase plate. This organization helps to ensure that in plate. This organization helps to ensure that in the next phase, when the the next phase, when the chromosomeschromosomes are separated, are separated, each new nucleus will receive one copy of each each new nucleus will receive one copy of each chromosome.chromosome.

Lesson On Cell MitosisAnaphaseAnaphase

The paired The paired chromosomeschromosomes separate at the separate at the kinetochoreskinetochores and move to opposite sides of the cell. and move to opposite sides of the cell. Motion results from a combination of Motion results from a combination of kinetochore kinetochore movement along the movement along the spindlespindle microtubulesmicrotubules and through the and through the physical interaction of physical interaction of polarpolar microtubulesmicrotubules..


TelophaseTelophase

ChromatidsChromatids arrive at opposite poles of cell, and new arrive at opposite poles of cell, and new membranes form around the membranes form around the daughter nucleidaughter nuclei. The . The chromosomeschromosomes disperse and are no longer visible under the disperse and are no longer visible under the light microscope. The spindle fibers disperse, and light microscope. The spindle fibers disperse, and cytokinesiscytokinesis or the partitioning of the cell may also begin or the partitioning of the cell may also begin during this stage.during this stage.

Lesson On Cell MitosisCytokinesis

In animal cells, cytokinesis results when a fiber ring composed of a protein called actin around the center of the cell contracts pinching the cell into two daughter cells, each with one nucleus. In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.


The The Cell CycleCell Cycle & & Mitosis Mitosis ReviewReview

Lesson On Cell MitosisCytokinesisCytokinesis



Early ProphaseEarly Prophase


Early Prometaphase


Late metaphase


Anaphase


Prokaryotic cellsProkaryotic cells undergo a process undergo a process similar tosimilar to mitosismitosis calledcalled binary fissionbinary fission. . However, the process of binary fission is very However, the process of binary fission is very much different from the process of mitosis, much different from the process of mitosis, because of the non-involvement of nuclear because of the non-involvement of nuclear dynamics and lack of linear chromosomes.dynamics and lack of linear chromosomes.

Mitosis occurs only in __________ Mitosis occurs only in __________ cellscells and and the process varies in different species.(? Fill in the process varies in different species.(? Fill in the blank). the blank).

End of Mitosis SlideshowEnd of Mitosis Slideshow

Lesson on cell mitosis

Education

cell mitosis mitosis

cell mitosis dna

cell mitosis g

cell mitosis errors

living cell

parent cell

process of mitosis

cell calledcytokinesiswhich