Homologous Chromosomes - Application of Biology - Lecture Notes, Study notes of Biology

Download Homologous Chromosomes - Application of Biology - Lecture Notes and more Study notes Biology in PDF only on Docsity! Meiosis The Problem an organism must inherit a complete set of genes from each parent but it’s gametes can only possess one set of genes. The Answer Meiosis Homologous Chromosomes An adult fruit fly has 8 chromosomes, (4 from each parent), these 2 sets are called homologous meaning that a chromosome from one parent has a corresponding chromosome from the other parent. How many homologous pairs does a human cell have? Diploid A cell that contains both sets of homologous chromosomes is called diploid. The number of chromosomes in a diploid organism is sometimes represented by the symbol 2N = 8. (fruit fly) Diploid cells contain 2 complete sets of genes. 2N = ? (human) Haploid Gametes only have a single set of chromosomes, thus it is called haploid. N = 4, for the fruit fly. N = ?, for humans What would happen if gametes were 2N? Meiosis A process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell. Meiosis has two stages: Meiosis I and Meiosis II. In meiosis a single diploid cell produces 4 haploid cells. Prior to Meiosis I, each chromosome is replicated. In prophase of M1 each chromosome pairs with its corresponding homologous chromosome to form a structure called a tetrad. Portions of the chromatids may be exchanged during a process called crossing-over. The pairs of homologous chromosomes separate meaning that each new cell will only have one set of genes (haploid) During Meiosis II, the sister chromatids separate. The two cells from M1 both enter M2, producing a total of 4 cells at the end of M2. Products of Meiosis Meiosis forms 4 sperm but only 1 egg due to a uneven division of cytoplasm (the other 3 cells produced are small polar bodies) Docsity.com