To identify the stages of mitosis in meristematic cells of onion root
INTRODUCTION
Mitosis (Greek myths, string) is the division of cell nucleus and the corresponding chromosome segregation into two daughter nuclei, which will be followed in the case of cell division, cytoplasmic division or cytokinesis. This process occurs in eukaryotic cells (because they have a nucleus) and, within them, in somatic cells, which are ordinary cells of the body. Http://es.wikipedia.org/wiki/Mitosis
. PHASES
entire process of cell division occurs after replication of genetic material, in other cell cycle phases, the process is divided into a series of phases : prophase, metaphase, anaphase and telophase.
The starting point of mitosis is called interphase, a state in which the cell has a distinct nucleus and chromosomes condensados.Esta not divide a three processes: "G1: Overview Protein-S: G2 DNA replication: Protein Synthesis After
Prophase
after DNA replication during interphase, is the condensation of the genetic material (DNA) (which normally exists as chromatin), which chromosomes are formed and the development of the bipolar mitotic spindle. One of the earliest prophase in animal cells is the migration of two pairs of centrioles to opposite ends of the cell. Appearance
Metaphase mitotic spindle that attaches to chromosomes at the centromere. The chromosomes move toward the equatorial plane, forming the equatorial plate (or metaphase). Anaphase
is shortest phase of mitosis, spindle microtubules she centrosomes separate longitudinally, leading to the separation of sister chromatids, which are directed to opposite poles.
telophase Telophase
reconstituted in chromatin, adopting the helical shape of chromosomes, the nucleolus appears and eucarioteca is reconstructed from the endoplasmic reticulum. MATERIAL
For team: 2 watch glasses, 1 burner, 1 light microscope, 1 dissection forceps, 1 dissection needle. Provided by Professor
: Colchicine at 0.1% and acertoceina. Provides the student
: 2 onions with sprouts, knife, cover slips and slides, sticky labels. DEVELOPMENT
A week before this practice put some onions in a small bottle with water so that only the base is submerged. Change the water every 24 hrs and transport onion very careful not to abuse her. We took the onion
water and cut the tips of the roots that were more obscure (2 mm long approximately) were categorized into two lots of work. We put the first batch in a flask with 0.1% colchicine. The second batch in a jar with water during the same time and same conditions served as control.
In a watch glass deposited rootlets treated with colchicine and in another in the control group and the label to avoid confusing. We cover
acertoceina both rootlets.
Heat with a flame burner until we started to smooth out the first vapors.
let cool and add more drops of food coloring.
repeat the steps above. We
raicilla, placed it on a clean slide and label them.
add a drop of acertoceina.
coverslip.
pressed with a pencil eraser turning the coverslip.
cleaned up the excess dye and observe the sample with the target of 40 X and determine the mitotic index of both lots and metaphysical. QUESTIONNAIRE
1 .- Why wait in their practice to find a higher rate of metaphases in treated rootlets colchicine?
For that inhibits mitotic spindle formation, giving the effect that the division stops at metaphase stage.
2 .- The number of nucleoli in interphase and mitosis observed in his practice tells you which of these two periods the cells stay longer? Explain.
If, where more time is interface remains in mitosis and nucleoli disappear and make out a few.
3 .- What is the risk of using substances such as colchicine in medicine, in treating certain diseases eg. Cancer and gout? Cause renal failure
4 .- Indicate the action of an agent and a mitogen mitostatico. Examples of both. Mitogen
An agent induces cell division.
QUESTIONNAIRE
1 .- Explain the results in terms of CO2 production in each of the 3 samples. The tube
control, there was a greater increase in the production of CO2 as it has no inhibitor. The tube
potassium cyanide (KCN) there was no CO2 production and inhibited it.
In the tube of 2.4-Dinitrophenol also increased less than even that of the control tube as it is uncoupling.
2 .- Explain that blocking the respiratory chain can be evidenced by the formation a product of the Krebs cycle.
There are certain substances such as 2.4-Dinitrophenol that make continued electron transport but not fosforilaciondel ADP and active in these conditions the respiratory process.
3 .- If you use other inhibitors such as amytal roteona or What results would you expect? Substances such as roteona
inhibit electron transport and phosphorylation of ADP, causing it to stop the breathing process.
4 .- Explain what their response would be if instead of CO2 production quantifies quantify consumption of O2.
would be similar because CO2 is a product of O2.
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