Agri 13 Principles of Genetics Laboratory Exercise 1 PDF

Agri 13 Principles of Genetics Laboratory Exercise 1 Understanding the Cell Cycle Mr. Roy R. Boten, L. Agr. Course Instructor  Importance of Cell Division - crucial in the process of heredity and variation - cells in all organisms grow and reproduce by cel...

Agri 13 Principles of Genetics Laboratory Exercise 1 Understanding the Cell Cycle Mr. Roy R. Boten, L. Agr. Course Instructor  Importance of Cell Division - crucial in the process of heredity and variation - cells in all organisms grow and reproduce by cell division - as long as the cell is growing and dividing, the physical and metabolic activities of the cells occur in a regular cycle and in a repetitive manner (cell cycle) INTERPHASE (Non-Dividing Phase) - nucleus is very distinct and enclosed by a definite nuclear membrane - presence of nucleoli and a granular network of darkly staining material called the chromatin Reference: Ramirez, D.A., Mendioro, M.S., & Laude, R.P. (2013). Lectures in Genetics. 10th Edition. Genetics and Molecular Biology Division, Institute of Biological Sciences, University of the Philippines – Los Baños G1 Phase. Nucleus and cytoplasm are enlarging toward mature size. Cell increases in volume by imbibing water and nutrients (building new protoplasm). S Phase. Active DNA synthesis (replication) and histones, components of the chromatin (2c = 4c after replication). G2 Phase. Active RNA and protein synthesis necessary for the chromosome. Double chromatin fiber is folded to form a chromosome. Parts of the Chromosome and its type (based on the location of the centromere) M or the Division Phase (Mitosis) - undergone by all somatic (body) and germ cells - means of increasing the number of cells and of replacing worn-out tissues the four stages of mitosis Reference: Ramirez, D.A., Mendioro, M.S., & Laude, R.P. (2013). Lectures in Genetics. 10th Edition. Genetics and Molecular Biology Division, Institute of Biological Sciences, University of the Philippines – Los Baños Prophase – chromosomes shorten, thicken, and become visible as thick rods Metaphase – chromosomes, which are maximally condensed and aligned at the equatorial plate Anaphase – the centromere becomes functionally double. Each member of the doubled chromosomes begins to move toward opposite poles. Telophase – the chromosomes regroup into two nuclear regions Relation to the study of heredity: The chromosome number remains constant through successive cell divisions. The chromosome makeup of the two daughter cells is the same as that of the parent cell, making mitosis an equational division. Meiosis - occurs during the process of gametogenesis (formation of gametes) - spermatogenesis (for male) & oogenesis (for female) - megasporogenesis (in higher plants) - consists of two consecutive divisions (Meiosis I and II) Meiosis I – Prophase I In Coleus, the somatic cells are diploid with 24 chromosomes. How many of each of the following is present in each cell at the stage of mitosis and meiosis indicated below: a. Kinetochores at prophase b. Chromosomes at anaphase c. Chromatids at metaphase I d. Chromosomes at telophase after cytokinesis e. Centromeres at anaphase f. Chromosomes at telophase II after cytokinesis g. Centromeres at anaphase I h. Chromatids at metaphase