Biology-Lesson-2 Cell Cycle and Cell Divisions PDF

Cell Cycle and Cell Divisions General Biology [1/2] Science, Technology, Engineering, and Mathematics Any sexually reproducing multicellular organism begins as a single-celled entity. 2 The single-celled entity then relies on cellular events to produce more cells, the early sta...

Cell Cycle and Cell Divisions General Biology [1/2] Science, Technology, Engineering, and Mathematics Any sexually reproducing multicellular organism begins as a single-celled entity. 2 The single-celled entity then relies on cellular events to produce more cells, the early stage of which is shown in the blastula. 3  Further growth and development proceed through the continuous reproduction and specialization of cells. The process repeats for as long as needed to ensure the maintenance and survival of an individual. 4 How do our bodies replenish cells? 5  Learning Objectives Lesso At the end of the lesson, you should be able to do the n2 following: Identify and describe the phases of the cell cycle. Explain the significance of the cell cycle control points. 6  Lesso The Genetic Material of Cells n2 DNA Molecule Almost every cell in our bodies has genetic material in the form of deoxyribonucleic acid (DNA). Most biological traits such as eye color, hair color, and height are coded for by the DNA. DNA is the genetic material in living cells. 7  Lesso DNA, the The Genetic Material of Cells n2 primary genetic material of living organisms, stores genetic information in the sequences of 8  Lesso The Genetic Material of Cells n2 Chromatin Interphase DNA is found in the form of chromatin, a complex of DNA and proteins. Chromatin in dispersed inside the intact cell nucleus during Interphase cells of onion interphase. 9  Lesso The Genetic Material of Cells n2 Chromosome Chromatin will sometimes need to further condense into a highly coiled and compact structure. This highly condensed form of Insect chromosomes are DNA is known as a highly condensed structures chromosome. when viewed under a microscope 10  Lesso The Genetic Material of Cells n2 Humans have 46 individual (or 23 pairs of) chromosome s. 11 You are looking at a diploid cell which consists of four pairs of chromosomes. After DNA replication, how many chromatids are there? How many of these do you think are homologous? 12 Tips Chromatin condenses into chromosomes. Each half of the chromosome is a chromatid. To help you remember this, imagine the chromatin to be a very thin string of DNA. Imagine the string being wound up into a thick rope. This thick rope is the chromosome. Now, imagine each half of that rope to be similar to the other half. These halves are the chromatids. 13  Lesso Introduction to Cell Cycle n2 All species of organisms have their own life cycle that shows how they are born, develop, and mature. Life cycle of various organisms 14  Lesso Introduction to Cell Cycle n2 Much like entire organisms, individual cells also have their own life cycle. The life cycle of a cell is known as the cell cycle, and this describes how cells grow, develop, and reproduce. 15 What are the different phases of the cell cycle and how does the cell make sure that these phases proceed smoothly? 16  Lesso Introduction to Cell Cycle n2 The cell cycle involves different phases that constitute a series of preparations for a cell to divide to produce new cells. 17  Lesso Stages of the Cell Cycle n2 Interphase Three Stages of the Cell M phase Cycle Cytokinesis 18  Lesso The Cell Cycle n2 Interphase - Gap 1 Interphase - S Interphase - Gap The phases 2 of the cell cycle M phase Cytokinesis 19  Lesso The Cell Cycle n2 Growth of Interphase - Gap Produce proteins, 1 cytoplasm and enzymes, nutrients, doubling of and energy Interphase - S organelles Interphase - Gap Events during 2 the G1 phase M phase Movement of centrioles of the Highest rate of centrosomes away to Cytokinesis protein synthesis await and assist the events of mitosis 20  Lesso The Cell Cycle n2 Interphase - Gap 1 Events during the S phase This stage is named S because it is Interphase - S when the cell synthesizes a copy of Interphase - Gap its DNA in a very notable process 2 called DNA replication. ○ This refers to the event when an M phase existing DNA produces another Cytokinesis copy of itself. 21  Lesso The Cell Cycle n2 Interphase - Gap 1 Interphase - S Interphase - Gap 2 M phase Cytokinesis 22  Lesso The Cell Cycle n2 Interphase - Gap Continued growth and 1 the production of materials that are Interphase - S necessary for cell Events division to occur Interphase - Gap during 2 the Gap 2 M phase phase Protein synthesis but not at the rate similar to that of the G1 phase Cytokinesis 23  Lesso The Cell Cycle n2 Interphase - Gap 1 Mitosis or Meiosis The M phase in eukaryotic Interphase - S organisms involves either one of Interphase - Gap two processes, namely, mitosis and 2 meiosis. ○ Sex cells or gametes undergo M phase meiosis, whereas somatic cells Cytokinesis or non-sex cells undergo mitosis. 24  Lesso The Cell Cycle n2 Interphase - Gap 1 Interphase - S Interphase - Gap 2 M phase Cytokinesis Cytokinesis is marked by the formation of a cleavage furrow in animal cells. 25  Lesso The Cell Cycle n2 Interphase - Gap 1 Interphase - S Interphase - Gap 2 M phase Cytokinesis Cytokinesis is marked by the formation of a cell plate in plant cells. 26 Remember The process of mitosis and meiosis refers to the division of the nucleus and genetic material. Cytokinesis, on the other hand, refers to the division of the cytoplasm. Cytokinesis can only occur once the genetic material is properly distributed to the daughter cells. 27  Lesso The Cell Cycle Checkpoints n2 G1-to-S checkpoint Cell Cycle G2-to-M checkpoint Checkpoints Metaphase checkpoint 28  Lesso The Cell Cycle Checkpoints n2 G2-to-M G1-to-S Checkpoint M Checkpoint Checkpoint Is the cell large enough with all the necessary energy reserves Is there any and doubled damage in the organelles? cell’s DNA? 29  Lesso The Cell Cycle Checkpoints n2 G2-to-M G1-to-S Checkpoint M Checkpoint Checkpoint Is the DNA Are the properly environmental replicated? conditions favorable for cell division to take Is there a place? presence of DNA damage? 30  The Cell Cycle Checkpoints G2-to-M G1-to-S Checkpoint M Checkpoint Checkpoint Are the spindles properly attached? Mitotic spindle 31  Lesso Let’s Sum It Up! n2 The life cycle of a cell is known as the cell cycle, and it describes how cells grow, develop, and reproduce. With very few exceptions, all of the cells in your body contain genetic material in the form of DNA or deoxyribonucleic acid, which is usually found in the nucleus of your 32  Lesso Let’s Sum It Up! n2 There are three main stages in the cell cycle, namely, interphase, M phase, and cytokinesis. Interphase is the stage when the cell prepares itself for eventual cell division, which can either be mitosis or meiosis. It is also the stage when the cell is metabolically active 33  Lesso Let’s Sum It Up! n2 Cytokinesis refers to the division of the cell’s cytoplasm and other components. This process significantly differs between animal cells and plant cells, primarily because of the presence of cell walls in the latter. 34  Lesso Let’s Sum It Up! n2 The cell cycle involves a series of events that lead to the production of cells. 35 Icons 36