AGR21 Lec2CPL (1) Principles of Genetics PDF

 AGRI 21 Principles of Genetics Christian Paul Lazaro Instructor 1 [email protected] AGRI 21 Principles of Genetics Christian Paul Lazaro  Chapter II The Ch...

 AGRI 21 Principles of Genetics Christian Paul Lazaro Instructor 1 [email protected] AGRI 21 Principles of Genetics Christian Paul Lazaro  Chapter II The Chromosomal Basis of Heredity AGRI 21 Principles of Genetics Christian Paul Lazaro  Learning Objectives At the end of the chapter, the student must: ✔ Identified the parts of a cell and identified the function of each; ✔ Described the structure of the chromosome; and ✔ Distinguished the process of mitosis from that of meiosis. AGRI 21 Principles of Genetics Christian Paul Lazaro ✔ Smallest structural and functional unit of an organism What is a CELL? https://www.thoughtco.com/animal-cells-vs-plant-cells-373375 AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Watery material which contains organelles that are involved in cell metabolism (active cell function). CYTOPLASM AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell The semipermeable membrane surrounding the cytoplasm of a cell. CELL MEMBRANE AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Gives the cell its shape and provides protection. CELL WALL https://www.thoughtco.com/cell-wall-373613 AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell A cytoplasmic double- walled membrane folded in layers that appear to be connected with the cell membranes. ENDOPLASMIC RETICULUM https://www.thoughtco.com/cell-wall-373613 AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Small bodies whose primary function is to provide cellular energy through respiration and oxidation. MITOCHONDRIA AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Net-like staining bodies commonly found in cells engaged in secretion. GOLGI APPARATUS AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Small particles which may be free floating in the cytoplasm or attached to the endoplasmic Chandramouli, et al., 2008 reticulum. RIBOSOMES https://botanystudies.com/ribosomes/ AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Organelle that duplicates itself and shows continuous inheritance between cell generations. CENTROSOME AND CENTRIOLE https://vectormine.com/item/centrosome-organelle-medical-vector-illustration-diagram/ AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Plastids in plant cell which contain chlorophyll and serve as the photosynthetic factory of the plants. CHLOROPLASTS https://www.turbosquid.com/3d-models/chloroplast-chloroplastid-stroma-3d-model/1129522 AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Primary director of cellular activity and inheritance. NUCLEUS https://discover.hubpages.com/education/cell-components-and-their-functions AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Controls movement into and out of the nucleus. NUCLEAR MEMBRANES https://discover.hubpages.com/education/cell-components-and-their-functions AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell Site of production of ribosomes. NUCLEOLUS https://discover.hubpages.com/education/cell-components-and-their-functions AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of a Cell ✔Chromatin ✔Chromosomes ✔Nucleoli NUCLEAR CONTENT https://micro.magnet.fsu.edu/ AGRI 21 Principles of Genetics Christian Paul Lazaro  Chromosome ✔ Dividing cell’s nucleus ✔ DNA and proteins ✔ Contains the genes Snustad & Simmons, 2012 AGRI 21 Principles of Genetics Christian Paul Lazaro  Chromosome ✔ Autosomal ✔ 3000 genes Snustad & Simmons, 2012 AGRI 21 Principles of Genetics Christian Paul Lazaro  Chromosome ✔ X chromosome ✔ Y chromosome Snustad & Simmons, 2012 AGRI 21 Principles of Genetics Christian Paul Lazaro  Chromosome Structure ✔ Centromere or Primary Constriction ✔ Secondary Constriction ✔ Arms ✔ Nucleolus- Organizing Region ✔ Chromomeres and Knobs https://courses.lumenlearning.com/wm-biology1/chapter/reading-chromosome-structure/ AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of Chromosome CENTROMERE or PRIMARY CONSTRICTION ✔Point of association between the chromosome and the spindle ✔It is where the kinetochore protein attach to AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of Chromosome SECONDARY CONSTRICTION ✔Pinching of a small chromosomal section forms the satellite ✔Associated with regions where nucleolus is formed or attached AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of Chromosome NUCLEOLUS- ORGANIZING REGION ✔Formation of nucleolus ✔Segments of chromosome that contain the genes for ribosomal RNA AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of Chromosome NUCLEOLUS- ORGANIZING REGION AGRI 21 Principles of Genetics Christian Paul Lazaro  Parts of Chromosome CHROMOMERE S and KNOBS AGRI 21 Principles of Genetics Christian Paul Lazaro Parts of Chromosome AGRI 21 Principles of Genetics Christian Paul Lazaro  Classification of Chromosome Position of Centromere ✔Metacentric “V” ✔Submetacentric “L” ✔Acrocentric “J” ✔Telocentric “i” AGRI 21 Principles of Genetics Christian Paul Lazaro  Classification of Chromosome Centric Activity ✔Monocentric ✔Diffuse/ Holokinetic/ Holocentric AGRI 21 Principles of Genetics Christian Paul Lazaro  Classification of Chromosome Chromosome Number ✔Basic chromosome number ✔Somatic number = diploid (2n) ✔Gametic number = haploid (n) AGRI 21 Principles of Genetics Christian Paul Lazaro ✔ Growth and development ✔ reproduction CELL DIVISION AGRI 21 Principles of Genetics Christian Paul Lazaro CELL CYCLE AGRI 21 Principles of Genetics Christian Paul Lazaro G1 Phase or Gap 1 Phase or First Growth Phase ✔Growth and differentiation ✔Cell increases in volume ✔Protein synthesis AGRI 21 Principles of Genetics Christian Paul Lazaro  S Phase or Synthesis Phase ✔DNA synthesis AGRI 21 Principles of Genetics Christian Paul Lazaro G2 Phase or Gap 2 Phase or Second Growth Phase ✔Chromosomal protein synthesis AGRI 21 Principles of Genetics Christian Paul Lazaro  M Phase or Mitotic Phase ✔Structural changes are visible AGRI 21 Principles of Genetics Christian Paul Lazaro  MITOSIS Mitosis in Onion Animal Mitosis AGRI 21 Principles of Genetics Christian Paul Lazaro  Mitosis ✔Somatic cells produce daughter cells via mitotic division ✔process of nuclear division, whereby duplicated DNA molecules are arranged into two separate nuclei AGRI 21 Principles of Genetics Christian Paul Lazaro Prophase ✔ DNA supercoils and chromosomes condense ✔ Chromosomes are comprised of genetically identical sister chromatids ✔ chromosomes shorten and thicken and the nucleolus diminishes in size ✔ Paired centrosomes move to the opposite poles of the cell and form microtubule spindle fibers ✔ nuclear membrane breaks down and the nucleus dissolves AGRI 21 Principles of Genetics Christian Paul Lazaro Metaphase ✔Microtubule spindle fibers from both centrosomes connect to the centromere of each chromosome ✔Microtubule depolymerization causes spindle fibers to shorten in length and contract ✔This causes chromosomes to align along the center of the cell AGRI 21 Principles of Genetics Christian Paul Lazaro Anaphase ✔sister chromatids separate and begin to move toward the opposite poles ✔poleward movement of the chromosomes is due to the depolymerization of spindle fibers attached to the kinetochore AGRI 21 Principles of Genetics Christian Paul Lazaro Telophase ✔Spindle fibers dissolve, and the chromosomes regroup into two nuclear structures ✔Chromosomes decondense ✔nuclear envelope reforms around each chromosome set AGRI 21 Principles of Genetics Christian Paul Lazaro Cytokinesis ✔Cytoplasmic division ✔Occurs concurrently with telophase AGRI 21 Principles of Genetics Christian Paul Lazaro Cytokinesis in Animal Cell ✔Cytokinesis proceeds by furrowing ✔Originates as an indentation of the outer membrane at the position of the metaphase plate ✔Centripetal AGRI 21 Principles of Genetics Christian Paul Lazaro Cytokinesis in Plant Cell ✔Formation of a cell plate ✔Phragmoplast is formed at the metaphase plate and acts as a framework for cell plate assembly ✔Centrifugal AGRI 21 Principles of Genetics Christian Paul Lazaro Consequences of Mitosis ✔Mitosis produces two daughter cells whose chromosomal compositions are identical to each other and to the parent cell ✔The chromosomes have several properties of interest with respect to genes ⮚ Chromosomes are reproduced and transmitted equally to the daughter cells so that these are identical to each other and to their parent cell AGRI 21 Principles of Genetics Christian Paul Lazaro Consequences of Mitosis ✔The gene retains its individuality regardless of the nature of its allele. The chromosomes also retain their individuality as indicated by the following proofs: 1.Chromosomes hold the same relative position at late anaphase to telophase as they enter the next prophase in the succeeding mitosis AGRI 21 Principles of Genetics Christian Paul Lazaro Consequences of Mitosis 2. The parts of the chromosome associated with the nucleolus remain associated during that interval 3.Homologues that have mutated retain their separate difference, mitosis after mitosis AGRI 21 Principles of Genetics Christian Paul Lazaro Mitosis…Mind Exercise Given: Onion, 2n = 16 Chromosomes at prophase? 16 Chromatids at metaphase? 32 Chromosomes at anaphase per pole? 16 Chromosomes at anaphase per cell? 32 Chromosomes after cytokinesis, per daughter cell? 16 AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS AGRI 21 Principles of Genetics Christian Paul Lazaro  Meiosis ✔Sexually reproducing organisms ✔Chromosome number of the cells is reduced to half its usual number ✔Maintenance of species’ chromosome number and production of genetically AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS I – Prophase I ✔ Leptotene Stage ⮚ Chromosomes are slender, long with many bead-like structures along their length ✔ Zygotene Stage ⮚ Pairing of homologous chromosomes begins ⮚ Paired homologous chromosomes form bivalents (II) because of synaptinemal complex ⮚ After the chromosomes are closely associated, molecular pairing occurs during which gene-by-gene matching takes place AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS I – Prophase I ✔Pachytene Stage ⮚ Chromosomes are thickened owing to coiling and are so closely appressed ⮚ Each of the chromosomes or bivalents consists of four chromatids ⮚ Crossing-over occurs ⮚ Nucleolus is particularly evident and certain chromosomes are attached to it AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS I – Prophase I ✔Diplotene Stage ⮚ Longitudinal separation of the bivalents initiates diplonema ⮚ Synaptinemal complex is no longer functional ⮚ Chromosomes are actively shortening ⮚ Terminalization occurs AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS I – Prophase I ✔Diakinesis ⮚ Chromosomes become more contracted ⮚ Nucleolus begins to disintegrate and the spindle formation begins ⮚ The nuclear membrane disintegrates and the spindle appears AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS I – Metaphase I ✔Bivalents move to the metaphase plate ✔Bivalents are oriented properly AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS I – Anaphase I ✔Chromosomes move from the metaphase plate to the poles ✔Homologues segregate from one another AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS I – Telophase I ✔Chromosomes regroup and their coiled structures begin to relax ✔Cytoplasm is divided ✔Nuclear membrane is formed AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS II – Prophase II ✔Similar to mitotic prophase ✔Chromosomes appear as double structures ✔Nucleolus and the nuclear membrane disintegrate ✔Microtubules extend across the cell to connect to the kinetochores of individual chromatids AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS II – Metaphase II ✔Chromosomes align on the equatorial plate ✔One sister chromatid is on each side of the metaphase plate AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS II – Anaphase II ✔Daughter chromosomes move toward the opposite poles ✔This separation marks the final division of the DNA AGRI 21 Principles of Genetics Christian Paul Lazaro MEIOSIS II – Telophase II ✔Chromosomes uncoil and lengthen ✔Nuclear membrane and the nucleolus reappear AGRI 21 Principles of Genetics Christian Paul Lazaro Cytokinesis ✔Cytoplasmic division ✔Varies considerably from species to species AGRI 21 Principles of Genetics Christian Paul Lazaro Consequences of Meiosis ✔Meiosis I is reductional division because each daughter nucleus contains only half the chromosome number of the parental cell ✔Meiosis II is equational division. Each of the two daughter nuclei of Meiosis I undergo mitosis, producing four haploid nuclei AGRI 21 Principles of Genetics Christian Paul Lazaro Consequences of Meiosis ✔Meiosis makes possible the conservation of the chromosome number from generation to generation in the sexually reproducing organisms ✔At Telophase I, each paternal and maternal chromosome has equal probability of being located at one or the other daughter nucleus AGRI 21 Principles of Genetics Christian Paul Lazaro Consequences of Meiosis ✔At the end of meiosis, each of the four daughter cells contains one representative of each pair of chromosomes present in the nucleus at the start of meiosis ✔Crossing-over between non-sister chromatids is the mechanism by which genes may be shuffled and exchanged AGRI 21 Principles of Genetics Christian Paul Lazaro Meiosis…Mind Exercise Given: Onion, 2n = 16 Bivalents at diakinesis? 8 Chromosomes at metaphase I? 16 Chromosomes at anaphase I per pole? 8 Chromosomes at metaphase II? 8 Chromosomes at anaphase II per pole? 8 AGRI 21 Principles of Genetics Christian Paul Lazaro  Life Cycles ✔ General Pattern of Eukaryotic Life Cycles ✔ The common theme involves the following: ❑ diploid phase, which is characterized by a series of mitotic divisions, ❑ meiosis, the first step in gamete formation ❑ a series of haploid mitotic divisions ❑ fertilization or fusion of two gametes or haploid nuclei AGRI 21 Principles of Genetics Christian Paul Lazaro 1. Terminal or Gametic Meiosis ✔ found in animals, including humans, and some lower plants ✔ It occurs just before the formation of gametes ✔ gametes are produced in gonads like testis and ovaries by the process called spermatogenesis and https://biology4isc.weebly.com/meiosis.html oogenesis AGRI 21 Principles of Genetics Micah Benize S. Gregorio-Balbas 1. Terminal or Gametic Meiosis https://biologyreader.com/difference-between-spermatogenesis-and-oogenesis.html AGRI 21 Principles of Genetics Christian Paul Lazaro  2. Intermediary or Sporic Meiosis ✔ characteristic of higher plants and some thalophytes ✔ It takes place sometime between fertilization and the formation of gametes ✔ In such cases, meiosis is followed by mitosis producing large number of https://biology4isc.weebly.com/meiosis.html gametes. It also produces microspores (in anthers) and megaspores (in ovaries). AGRI 21 Principles of Genetics Christian Paul Lazaro 2. Intermediary or Sporic Meiosis Ramirez, Mendioro& Laude, 2013 AGRI 21 Principles of Genetics Christian Paul Lazaro 2. Intermediary or Sporic Meiosis www.slideserve.com AGRI 21 Principles of Genetics Christian Paul Lazaro 3. Initial or Zygotic Meiosis ✔ exhibited by some algae, fungi, and diatoms ✔ characterized by the occurrence of meiosis immediately after fertilization https://biology4isc.weebly.com/meiosis.html AGRI 21 Principles of Genetics Christian Paul Lazaro 2. Intermediary or Sporic Meiosis Ramirez, Mendioro& Laude, 2013 AGRI 21 Principles of Genetics Christian Paul Lazaro  QUESTIONS OR CLARIFICATIONS? AGRI 21 Principles of Genetics Christian Paul Lazaro QUIZ? Get in Touch WithusUs Send a message or visit us City of Batac, Ilocos Norte, Philippines (63) 77-600-0459 [email protected] Follow us for updates facebook.com/MMSUofficial www.mmsu.edu.ph