ST. LAWRENCE HIGH SCHOOL a JESUIT CHRISTIAN MINORITY INSTITUTION Sub: Life Science Class: X Date: 30.04.2020

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ST. LAWRENCE HIGH SCHOOL A JESUIT CHRISTIAN MINORITY INSTITUTION Sub: Life Science Class: X Date: 30.04.2020 CHAPTER: CONTINUITY OF LIFE TOPIC: CELL DIVISION WORKSHEET 21 Choose the correct option: (1X15=15) 1. Which of the following properties are present in a cell produced as a result of cell division? a. Structural b. Genetical c. Physiological d. All of these 2. Continuity of life is mainly brought about by a. Cell differentiation b. Cell elongation c. Cell division d. Both a& b 3. Cell division is related to a. Evolution b. Continuity of life c.Botha&b d. None of these 4. The first cell of the new generation in multicellular organism is a. Zygote b.Fertilized egg c. Both a&b d. none of these 5. Which of the following is caused to the tissues by the process of cell division? a. Repair b. Regeneration c. Both a&b d. None of these 6. In which of the following Amitosis type of cell division is mainly observed? a. Prokaryote b. Protozoan c. eukaryote d. Both a&b 7. Which of the following is considered as a direct type of cell division process? a. Mitosis b. Amitosis c. Meiosis d. All of these 8. Which of the following type of cell division gives rise to two daughter cells from one cell? a. Amitosis b. Meiosis c. Both a&b d. None of these 9. Which of the following cells undergo amitosis? a. Somatic cells b. Sex cells c. Gametes d. Both b&c 10. During Amitosis, the Nucleus takes the following shape? a. Round b. Dumb-bell shape c. Oval d. ellipsoid 11. Which of the following type of cell division helps in constant chromosome number of a species? a. Mitosis b. Meiosis c.Amitosis d. Both a&b 12.The nucleus undergoes complicated changes in a. Mitosis b. Meiosis c.Amitosis d. Both a&b 13. In which of the type of cell division does constriction of intact nucleus takes place? a. Meiosis b. Amitosis c. Binary fission d. Both b& c 14. Spindle formation doesn’t take place in a. Meiosis b. Amitosis c. Mitosis d. Both a &c 15. Which of the following organism doesn’t undergo Amitosis? a. Amoeba b. Bacteria c. Fungi d. Stem cells -Debjani Chakraborty .

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Cell Cycle and Division
CELL CYCLE AND DIVISION Chapter CELL CYCLE AND DIVISION Day - 1 CELL CYCLE – Cell cycle completed into two phases. – Interphase – G0 Phase – G1 Phase – S Phase – G2 Phase – Division phase or M phase – Karyokinesis – Cytokinesis INTERPHASE Interphase is phase between two cell division. In this phase cell prepares itself for division so, called preparatory phase. It is longest phase of cell cycle. It covers approx. 95% of cell life. It is also called resting phase but extremely active. In this phase synthesis of DNA, RNA and protein takes place G1 - PHASE (6 – 15 HR.) Most variable phase for duration. Cell growth occurs in this phase, so most probably it is longest stage of interphase. Mitochondria, Chloroplasts (plants), Lysosomes, Ribosome, Endoplasmic Reticulum Golgi Complex, Vacuoles etc. are produced. In nucleus m-RNA, t-RNA and r-RNA synthesized. Structural and functional proteins are formed. Metabolic rate of the cell becomes very high. S - PHASE (6-10 HR.) Longest phase in human interphase. Replication of DNA takes place. (DNA get doubled) Histones are synthesized that cover each strand of DNA. Centrosome (Centriole) replicate is late S-phase. This phase indicated cell is ready for cell division. G2 - PHASE (3 - 12 HR.) CELL BIOLOGY Page 1 CELL CYCLE AND DIVISION Tubulin protein synthesis start for spindle formation. This phase may be called post DNA synthesis phase. Duplication of Mitochondria, Chloroplast and Golgi Body take place. Cell division involves enormous expenditure of energy thus cell stores ATP in G2 phase After G2 phase cell enters in division or M-phase CAUSE OF CELL DIVISION Kern plasm theory: (Hertwig) Mitosis occurs due to disturbance in karyoplasmic index (KI) of cell.
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Amitosis As a Strategy of Cell Division - Insight from the Proliferation of Tetrahymena Thermophila Macronucleus
bioRxiv preprint doi: https://doi.org/10.1101/2020.08.11.247031; this version posted August 11, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Amitosis as a strategy of cell division - Insight from the proliferation of Tetrahymena thermophila macronucleus Y.X. Fu1,3,∗,+, G.Y. Wang2,4,∗, K. Chen2,4,X.F. Ma2,4, S.Q. Liu3 & W. Miao2,+ 1 Department of Biostatistics and Data Science, and Human Genetics Center, School of Public Health, The University of Texas Health Science Center, Houston, Texas 77030, USA 2 Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China 3 Key Laboratory for Conservation and Utilization of Bioresources, Yunnan University, Kunming 650091, China, 4 University of Chinese Academy of Sciences, Beijing, 100049, China ∗ These authors contributed equally to the work. + Corresponding authors. Cell division is a necessity of life which can be either mitotic or amitotic. While both are fundamental, amitosis is sometimes considered a relic of little importance in biology. Nevertheless, eu- karyotes often have polyploid cells, including cancer cells, which may divide amitotically. To understand how amitosis ensures the completion of cell division, we turn to the macronuclei of ciliates. The grand scheme governing the proliferation of the macronuclei of ciliate cells, which involves chromosomal replication and the amito- sis, is currently unknown. Using a novel model that encompasses a wide range of mechanisms together with experimental data of the composition of mating types at different stages derived from a single karyonide of Tetrahymena thermophila, we show that the chro- mosomal replication of the macronucleus has a strong head-start effect, with only about five copies of chromosomes replicated at a time and persistent reuse of the chromosomes involved in the early replication.
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