DNA, Genes and Chromosome

  • Nucleus- Controls the activitie of the cell and has genetic information.
  • Chromosome- Contains the genetic information - 23 pairs of these in humans. 46 in total.
  • Genes- carries the code to make one proteien - sections of a chromosome.
  • DNA- Contains coded information
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Structure and function of DNA

  • Chromosomes are made of DNA.
  • DNA is found in the nucleus and carries the genetic instructions to amke proteins.
  • DNA is described as a double helix - made of two strands which are twisted.
  • The strands are joined by bases - four types of bases- A + T     G + C  

      - Adenine

      - Thymine

      - Guanine

      - Cytosine

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Key sentence!

The sequence of bases determines the sequence of amino acids which determines the structure and function of the protein.!!!!!!!!!!!!!!!!!!!!

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Producing Proteins

  • A section of DNA is called a gene.
  • Each gene codes for a specific protein.
  • Proteins are very important becasue they determine the characteristics of the organism.
  • Proteins are made by a chain of amino acids (joined by peptide bonds).
  • mRNA carries a copy of the gentic code from DNA in the nucleus to a ribosome in the cytoplasm. (Ribosomes are where protein is made)
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Stages of protein synthesis

1. DNA unwinds and a single-stranded complementary copy of it is produced, called mRNA.

2. mRNA carries the copy of the code from the nucleus to a ribosome in the cytoplasm.

3. At a ribosome, amino acids are placed in order, according to eacjh triplet of bases on mRNA.

4. Amino acids join together by peptide bonds to make a protein!

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