This will include basic info on genetics!

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  • Created by: Paige
  • Created on: 27-01-12 17:11


  • There are approximately 23,000 genes in the human genome.
  • Genes are the units of instruction that the cells of the human body use to carry out their functions.
  • There are over 200 different types of cells in the human body (for example, muscle cells, liver cells, and nerve cells).
  • A genome is the complete collection of hereditary information for an individual organism. In cellular life forms, the hereditary information exists as DNA.
  • (
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  • A chromosome, by definition, is a threadlike strand of DNA in a cell nucleus that carries genes.
  • Human cells have 23 pairs of nuclear chromosomes. A chromosome is made up of a DNA molecule that contains genes.
  • There are 24 distinct human chromosomes out of which 22 are autosomal chromosomes and the remaining two are sex-determining chromosomes.
  •  Every individual has two sets of the 22 chromosomes, X chromosome from the mother and an X or a Y chromosome from the father.
  • Chromosomes are in the nucleus.
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Inheritance (Genes)

  • Living organisms are a product of genes that they inherit and enviromental factors that have acted on them.
  • A gene is a section of DNA.
  • The DNA molecule is made up of base pairs. Genes are sections of these.
  • A human gene may be 3,000 base pairs long of a chromosome.
  • Each gene is a code specifying a particulat combination of amino acids, that will make a specific protein.
  • Different versions of a gene is called an allele.
  • If yu have a brown eyes allele from one parent and a blue eye allele from the ther parent. The blue allele will not show.
  • It takes 8 hours for 1 of your cells to completely copy it's DNA.
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Genetic Crosses!

  • Humans have 23 pairs of chromosmes.
  • Your gender is controlled by pair 23 called the sex chromosome.
  • They are represented by X AND Y.
  • XX represents girl.
  • XY represents boy.
  • The possible genders for parents would be XY or XX.
  • Punnett square:


     F                     X             X       


     T             X     XX          XX


     E             Y    YX           YX


50% chance of a boy

50% chance of a girl

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  • A different version of a gene is called an allele.
  • One allele is always dominent
  • One allele is always recessive
  • If you inherit a dominent allele you will have his characteristic
  • If you inherit a recessive allele it will only show affect if both parents have it.
  • Dominent alleles with a capital letter
  • Recessive alleles with a lower letter.
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