Mitosis and Meiosis PDF

of repaicing oid, worn out and injured body cells. Mitosis is also involved in the asexual reproduction of the - E ,C a s multiceilular organisms. The newly-formed daughter celi has a period of growth, after which it reaches the- fate of its mother celi ! , x (division). This life span of a cell is...

of repaicing oid, worn out and injured body cells. Mitosis is also involved in the asexual reproduction of the - E ,C a s multiceilular organisms. The newly-formed daughter celi has a period of growth, after which it reaches the- fate of its mother celi ! , x (division). This life span of a cell is called the cell cycle. Each ce11 thus, has two phases in its li{e cycle: 1'Phase of growth or inter-phase and Phase ,! of division or mitotic phase. Meiosis: lt consists of trvo 'l.., successive divisions which occur in ,1 and cell) (reproductive cell a diploid t'.. forms four new and haPloid ceils.: (gametes). A diploid cell has two sets of chromosomes while a haploid II cel1 has one set of chromosomes. -I I Meiosis occurs Prior to gamete f ormation (called oogenesis and Figure 37" Mitosis and Meiosis spermatogenesis in animals) for the sex-ual reproduction. Gametes (ova and sperms) are always hapioid. The first division of meiosis (meiosis i) is a reductional division. The chromosome number of two daughter cells is half that of the mother cell, that is, from diploid to haploid nature. In this di however, each chromosome remains replicated or made of two chromatids. The two chromatids a chromosome often become different due to crossing over or exchange of genes-bearing betweenthe two similar orhomologous chromosomes of the mother cell' The second division of meiosis (meiosis II) is similar to mitosis and is cal1ed equational di In this case, the two daughter chromatids of each chromosome separate and form new The number of the chromosomes remains haploid as after meiosis I. Meiosis. is essential for the sexual reproduction as it produces haploid gametes (e.g', ova spermatozoa in animals). Two such gametes (ma1e and female) fuse and form a diploid zygole' btdy of the individual develops by mitotic divisions of zygote and its daughter cells. l I 14 ' dl I a'.l i @ Differences betr'r'een Mitosis and Meiosis \{itosis 1s produces trr'o iiar-L{htcr.e1 ts 2. Ploidv: The lli'rsit'i'. ii,i', Number: E.r sinSle.livrsion tclk€ It can occur the 5. Variations: 40 It does t-rot pl'r-'l1uce ^ t"ariatior-rs' The Fundomentol Unit of Life: