Biology Genetics Complete Solutions

Biology Genetics Complete Solutions Genes A segment of DNA on a chromosome. Genes control the production of proteins. Each chromosome consists of hundreds of genes, each gene playing an important role in determining the characteristics and functions of the cell. Human body cells have how many chromosomes? 46 Brainpower Read More How many chromosomes does a parent contribute? 23 chromosomes, resulting in 23 pairs of chromosomes for the offspring. 1. Homologous chromosomes are? 2. Homologous chromosomes in body cells have the same? 3. Homologous chromosomes carry what at the same location? 1. Chromosomes that make up a pair, one chromosome from each parent. 2. Homologous chromosomes in body cells have the same length and same centromere position. 3. Homologous chromosomes carry genes for any given trait at the same location, but they may not be similar. An example of this is earlobe type. Gametes Sex cells that have half the number of chromosomes. Haploid cell A cell that is half the number of chromosomes that species has. A cell with N number of chromosomes. Fertilization The process by which one haploid gamete combines with another haploid gamete. Diploid cell A cell that contains 2n the number of chromosomes. Meiosis A type of cell division that reduces the number of chromosomes in a cell for sexual reproduction. Occurs in the reproductive structures of organisms that reproduce sexually. How many consecutive cell divisions stages does meiosis have? Two; Meiosis I and Meiosis II What are the stages of Meiosis I? Interphase, Prophase I, Metaphase I, Anaphase I, and Telophase I. (IPMAT) Describe the following stage of Meiosis I: Interphase 1. Chromosomes replicate i.e. Replication of DNA. 2. Chromatin condenses. 3. Synthesis of proteins occur. Describe the following stage of Meiosis I: Prophase I 1. Pairing of homologous chromosomes occurs, each chromosome consists of two sister chromatids. 2. Crossing over produces exchange of genetic information. 3. The nuclear envelope breaks down. 4. Spindles form. 5. Replicated chromosomes become visible 6. Centrioles move to the cell's opposite poles Crossing over The process during which chromosomal segments are exchanged between a pair of homologous chromosomes. Describe the following stage of Meiosis I: Metaphase I 1. Chromosomes centromeres attach to spindle fibers. 2. Homologous chromosomes line up at the equator. 3. These chromosomes are diploid What is an important distinction between the metaphase (I) mitosis and meiosis? During metaphase in mitosis, the individual chromosomes line up at the cell's equator. During metaphase I of meiosis, the homologous pairs chromosomes line up as pairs at the cell's equator. Describe the following stage of Meiosis I: Anaphase I 1. Homologous chromosomes begin to separate and move to opposite poles of the cell. 2. The chromosome number is reduced 2n to n when homologous chromosomes separate. 3. Each homologous chromosome still consists of two sister chromatids Describe the following stage of Meiosis I: Telophase I 1. Homologous chromosomes reach opposite poles of the cell. 2. The spindles break down 3. Chromosomes uncoil and form two nuclei 4. The cell divides What are the stages of Meiosis II? Prophase II, Metaphase II, Anaphase II, and Telophase II. (PMAT) Describe the following stage of Meiosis II: Prophase II 1. Chromosomes condense 2. Spindles form in each new cell 3. Spindle fibers attach to chromosomes Describe the following stage of Meiosis II: Metaphase II 1. Centromeres of chromosomes line up randomly at the equator of each cell 2. These chromosomes are haploid Describe the following stage of Meiosis II: Anaphase II 1. Centromeres split 2. Sister chromatids are pulled apart by spindle fibers and move to opposite poles Describe the following stage of Meiosis II: Telophase II 1. Four nuclei form around chromosomes 2. Spindles break down 3. Cells divide Describe the products of meiosis. Four cells have formed each nucleus containing a haploid (n) number of chromosomes.