GCSE Science - B1 - You and Your Genes - Genes, Chromosomes and DNA

GCSE Science - B1 - You and Your Genes - Genes, Chromosomes and DNA

1. Genes are Instructions for Cells

   • Each gene is a code for making a certain protein. Proteins are the building blocks for cells.. Having different versions of proteins means that we end up with different characteristics.
   • 1.
     • Some proteins are structural proteins. They're part of things like skin, hair and blood.
   • 2.
     • Other Proteins are functional proteins. For example, enzymes are proteins that help with digestion by breaking down food molecules - amylase is a digestive enzyme that breaks down starch

2. An Organism's Genotype Describes the Genes It's Got

   • 1.
     • An organism's genotype is all of the genes it has. The characteristics that an organism displays are called its phenotype.
   • 2.
     • Some characteristics, e.g. dimples, are controlled only by genes. This can just be one gene, or quite often the characteristic is controlled by several genes working together, e.g. eye colour.
   • 3.
     • Other characteristics, e.g. scars are controlled only by environmental factors. They don't have anything to do with genes.
   • 4.
     • There are also characteristics that are controlled by both genes and environmental factors. For example, weight - if both your parents are skinny, you'll probably be skinny.