B5 genes

  • Created by: sofia84
  • Created on: 09-10-18 18:24
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  • B5- genes
    • genes and chromosomes
      • Chromosomes are made of DNA and are found inside the nucleus
      • Each chromosome contains a number of genes
      • A gene is a section of DNA that codes for a protein
        • A genome is an organism's complete set of genes
    • Genotype and Phenotype
      • Genes are responsible for our characteristics
      • we have two copies of every chromosome in our cells, therefore we have two copies of each gene
      • Th different forms of each gene are called alleles
      • We use capital or lowercase to show if the alleles are dominant or recessive
      • eg, if there are two dominant alleles for brown eyes this would be shown as BB
        • If two recessive alles are present for blue eyes this would be bb
          • If one of each allele is present eg Bb then the dominant characteristic is seen so the eyes are brown
      • The phenotype is the characteristic seen
      • The genotype is the genes that are present
      • A heterozygous person has two different alleles eg Bb
        • A homozygous person has both alleles the same eg bb
    • Inherited variation is cause by the genes inherited from the parents
      • Environmental variation is caused by environmental factors
        • skin colour
        • even if someone has tall genes they may still be short due to mall nourishment
        • weight
        • intelligence
      • eyecolour
      • blood group
      • inherited diseases
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