Explain How Eukaryotic Chromosomes Store a Unique Genotype, Discussing How the Processes of Independent Assortment, Mutation and Crossing over Contribute to Genetic Variation Amongst Individuals

D1- Explain how eukaryotic chromosomes store a unique genotype, discussing how the processes of independent assortment, mutation and crossing over contribute to genetic variation amongst individuals

Introduction

DNA molecules store the genetic blueprint of an animal, in other words that is called the genotype, or genome. The genome is stored around protective histone proteins (nucleosomes) and packaged into one or more chromosomes. They are coiled and packed very tightly. Inside a DNA molecule there are many different sections that each code for a particular characteristic/trait. This is called a gene. In eukaryotic organisms, DNA is held in the nucleus of the cell, and two copies of each gene are usually present, this is known as the diploid state. The position of the gene on a chromosome or DNA molecule is termed as the locus, and an allele is one of the different forms of a particular gene. Sex chromosome pairs often look different (heterosomes) the other pairs look similar (autosomes). To determine whether it is a heterosome, or autosome, you can use a karyotype, which involves looking under a microscope to see a diving nucleus to find out what type it is.

Genes will determine almost everything in a new born baby, from gender, to blood type, and from eye colour to height. Many health conditions and diseases can also be genetic. Genes come in pairs, one gene will be inherited from the mother and another gene from the father, some genes will be dominant, whereas some will be recessive.

DNA in the nucleus is called chromatin, appearing in photomicrographs as denser, darker heterochromatin and lighter euchromatin. Heterochromatin includes mainly non-active DNA, centromeres and telomere, nevertheless they are still very important in helping with cell division.

For DNA to divide and be duplicated, it goes through a process of replication, and this is where DNA is copied during mitosis and this is termed semi-conservative because each new cell contains DNA...