Meiosis 3p4d73

FACULTY OF APPLIED SCIENCES BIO 150 METABOLISM AND CELL DIVISION (SEM NOVEMBER 2014-APRIL 2015) LABORATORY REPORT EXPERIMENT 7:CELL REPRODUCTION II Date of Experiment:11.02.2015 Date of Submission:12.022015

INTRODUCTON Meiosis is the singularly important biological event that not only maintains a constant chromosomes number for most species of plant or animals, but also provides a means of genetic variable because of crossing over and the subsequent exchange of genetic material. In meiosis, immature or primordinal germ cells undergo a ‘reduction’ in the diploid number of chromosomes characteristic for the species and become mature gametes. In this study, meiosis will be studied as it occurs in the development o nature pollen grains the flowering plants. This pollen grains give rise to male gametes, which fuse within an egg produce a zygote.

OBJECTIVES 1. To observe and identify the stages of meiosis in Lily’s anther. 2. To observe and identify the stages of meiosis from a given slide.

APPARATUS       

Microscope Slide of lilium root tip mitosis Slide of lilium anther early prophase Slide of lilium root tip mitosis Slide of lilium root tip Slide of lilum anther first divisions Slide of lilium anther late prophase

PROCEDURE

1. 1 cm of apical was cut of from the lilium 2. The lilium was placed on the watch glass containing acetic orcein stain and HCL in the approximately proportions of the ten parts of stain to one parts of acid. 3. The watch glass was warmed, but not boiled, for five minutes on the spirit lamp. The acid helps the tissue to macerated so that the stain can be easily absorbed. 4. 3 mm of the lilium was cut and the part was discarded furthest from the apex. 5. Two or three drops of acetic orcein added to the lilium. 6. The lilium was broke with a needle so as to spread it out as thinly as posibles without interfering too much with arrangement of the cells. 7. The cover slips was put on, covered with filter paper and squashed gently. 8. The slide was warmed on the spirit lamp for about ten secinds to intensify the staining. The slide should be warmed but not to hot to touched. 9. The stages in meiosis was examained. 10. A labeled diagram for each stage was provided. 11. There was a simplified notes on the changes that occur in every stages in meiosis besides the labeled diagram.

OBSRVATIONS DIAGRAM Prophase II

NOTES New spindle apparatus is formed on each of the two cells from telophase I. the stillduplicated chromosomes stretch out and then

recondense. Spindle microtubules from each pole attach to the kinetochores of each of the sister chromatids. Metaphase II The duplicated chromosomes are aligned along the equator by the spindle complex in each of the two cells.

Anaphase II Centromeres of sister chromatids are separated from

each

other

and

the

now

single

chromosomes are pulled to the poles of the two cells.

Telophase II Each new nucleus formed has half the number of the original chromosomes and eacg nucleus has

one

of

each

type

of

homologous

chromosome. Cytokinesis results in a total of four new cells, the haploid products. QUESTIONS 1. Where else you can find this process in Lily? Anther. 2. How do you identify the meiotic division that occurs in the lilium anther? The meiotic divisions is half the number of chromosomes as the parent. Four haploid microscope will produce in each germ cell in the male organs or anther which undergoes

meiosis in the lily. Six rows of ovules in the lily ovulary, can produre egg cells by meiosis. Meiosis I and Meiosis II are the two consecutive divisions in meiosis. The two of each pair of chromosomes separated in first meiotic divisions, the identical chromatids of each chromosomes are separated in the second meiotic divisions. 3. Give the significance of meiotic process in organisms. The ovule and ovary are given in variation in genetic. 4. Give the difference between the meiotic and mitotic process that occur in Lily. Meiotic Process Mitotic Process There are two cell division, the first and the The cell divide only once. second meiotic divisions. Chromatids of two homologous chromosomes The two chromosome do not exchange exchange segments during crossing over. segments during prophase. There is no centromeric division uring Divisions of the centromers take place during anaphase I. Centromers divide only during anaphase. anaphase II Occurs in germ cells Spindle fiber do not reappear at telophase I.

Occurs in the somatic cells of the body Spindle fibers disappear completely telophase.

in