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DNA - PowerPoint PPT Presentation


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DNA. What is DNA?. A code in the cell that contains the hereditary material The code is a chemical called deoxyribonucleic acid Every cell in your body contains DNA. DNA Structure. Rosalind Franklin discovered that DNA is two chains of molecules in a spiral form by using an X-ray

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PowerPoint Slideshow about 'DNA' - aimee-hampton


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Presentation Transcript
what is dna
What is DNA?
  • A code in the cell that contains the hereditary material
  • The code is a chemical called deoxyribonucleic acid
  • Every cell in your body contains DNA
dna structure
DNA Structure
  • Rosalind Franklin discovered that DNA is two chains of molecules in a spiral form by using an X-ray
  • Similar to twisted ladder
  • James Watson & Francis Crick made a model of DNA molecule
a dna model
A DNA Model
  • Each side of the ladder is made of sugar-phosphate molecule
  • Called the “backbone”
  • Sugar = deoxyribose
slide5

Rungs of the ladder are made up of nitrogenous bases

  • There are four types of bases
    • Adenine (A)
    • Guanine (G)
    • Cytosine (C)
    • Thymine (T)
base pairing
Base Pairing
  • Adenine always pairs with Thymine

A-T

  • Cytosine always pairs with Guanine

C-G

copying dna
Copying DNA
  • The two sides of DNA unwind and separate
  • Each side becomes a pattern for a new DNA strand
genes
Genes
  • DNA in your cells stores the instructions for making proteins
  • Each chromosome contains hundreds or thousands of genes
making proteins
Making Proteins
  • Genes are found in the nucleus, but proteins are made on ribosomes in the cytoplasm
  • The code for making proteins are carried from the nucleus by RNA or Ribonucleic Acid
ribonucleic acid
Ribonucleic Acid
  • RNA is different from DNA
    • RNA is not a spiral, but one single strand
    • RNA has the bases A, G, C, and U not T
      • U = Uracil
    • Sugar is ribose, not deoxyribose
types of rna
Types of RNA
  • Messenger RNA (mRNA)
  • Transfer RNA (tRNA)
  • Ribosomal RNA (rRNA)
controlling genes
Controlling Genes
  • Each cell only uses some of the thousands of genes to make proteins
  • Cells must be able to control genes by turning some genes on and others off
mutations
Mutations
  • Permanent changes in the DNA sequence of a gene
  • These happen when the DNA is not copied correctly
  • They cause incorrect proteins to be made
causes of mutations
Causes of Mutations
  • X-rays
  • Sunlight
  • Some chemicals
results of mutations
Results of Mutations
  • Some mutations are beneficial
    • They add variety to the species
  • Many mutations are harmful and can cause death
    • Cystic Fibrosis
  • Some mutations have no effect on the organism