{"id":35291,"date":"2022-11-22T16:14:30","date_gmt":"2022-11-22T10:44:30","guid":{"rendered":"https:\/\/tsboardsolutions.com\/?p=35291"},"modified":"2022-11-22T16:14:30","modified_gmt":"2022-11-22T10:44:30","slug":"ts-inter-1st-year-botany-notes-chapter-11","status":"publish","type":"post","link":"https:\/\/tsboardsolutions.com\/ts-inter-1st-year-botany-notes-chapter-11\/","title":{"rendered":"TS Inter 1st Year Botany Notes Chapter 11 Cell Cycle and Cell Division"},"content":{"rendered":"
Students can go through TS Inter 1st Year Botany Notes<\/a> 11th Lesson Cell Cycle and Cell Division will help students in revising the entire concepts quickly.<\/p>\n \u2192 Cell division is a process by which a cell duplicates for growth and reproduction of an organism.<\/p>\n \u2192 Virchow proposed that new cells arise from pre-existing cells by division. This is i called cell lineage theory.<\/p>\n \u2192 Somatic cells divide by a process of mitosis while the germ cells divide by a process called meiosis (reduction division).<\/p>\n \u2192 In mitosis daughter cells have exactly the same number of chromosomes of the parent cell.<\/p>\n \u2192 Duplication of DNA molecules and doubling of chromosomal constituents are observed during S – phase of interphase.<\/p>\n <\/p>\n \u2192 Mitosis includes karyokinesis and cytokinesis. Karyokinesis occurs in four stages.<\/p>\n \u2192 During prophase nucleolus and nuclear membrane disappear. Chromatin condenses into chromosomes, each having two chromatids.<\/p>\n \u2192 During metaphase, spindle fibres are formed. Spindle fibres attach to the centromere of chromosomes. Chromosomes move to the centre of the spindle.<\/p>\n \u2192 In Anaphase centromere divides. Daughter chromosomes move to opposite poles.<\/p>\n \u2192 In Telophase nucleolus and nuclear membrane reappear. Chromosomes J decondense into chromatin. Two daughter nuclei are formed.<\/p>\n \u2192 Cytokinesis, is by cell plate method. Two daughter cells are formed.<\/p>\n \u2192 In meiosis, karyokinesis and cytokinesis occur two times.<\/p>\n \u2192 Meiosis I is a reductional division.<\/p>\n \u2192 Prophase t is the longest stage and is divided into 5 stages. \u2192 In Metaphase I, the bival\u00e9nts come to be at the equator.<\/p>\n \u2192 In Anaphase I, homologous..chromosomes separate. Each chromosome of a pair moves to opposite poles of the spindle.<\/p>\n <\/p>\n \u2192 In Telophase I, reappearance of nuclide and nudear membrane results in the formation of two haploid nuclei.<\/p>\n \u2192 The events of meiosis Il are similar to mitotic divisio\u00f1. Thus it is an equational division. Four haploid cells are formed. Daughter cells produced are called gametes br spores.<\/p>\n \u2192 Crossing over results in exchange of genetic information between individuals of spores and evolution of species.<\/p>\n","protected":false},"excerpt":{"rendered":" Students can go through TS Inter 1st Year Botany Notes 11th Lesson Cell Cycle and Cell Division will help students in revising the entire concepts quickly. TS Inter 1st Year Botany Notes 11th Lesson Cell Cycle and Cell Division \u2192 Cell division is a process by which a cell duplicates for growth and reproduction of … Read more<\/a><\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[27],"tags":[],"yoast_head":"\nTS Inter 1st Year Botany Notes 11th Lesson Cell Cycle and Cell Division<\/h2>\n
\n(a) In leptotene, chromosomes become distinct being quite long and uncoiled.
\n(b) In zygotene, pairing of homologous chromosomes – synapsis occurs.
\n(c) In pachytene, exchange of genetic material (crossing over) occurs between non sister chromatids of the bivalent.
\n(d) In diplotene, repulsion starts between homologous. Chiasmata show terminalisation process.
\n(e) In diakinesis, nucleolus and nuclear membrane disappear.<\/p>\n