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DNA

DNA. DNA. An organism’s genetic material Located on chromosomes Genes are segments on DNA Contains information needed for an organism to grow, maintain itself, and reproduce C ontains the instructions for making specific proteins. DNA Structure. A double helix shape (twisted ladder)

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DNA

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  1. DNA

  2. DNA • An organism’s genetic material • Located on chromosomes • Genes are segments on DNA • Contains information needed for an organism to grow, maintain itself, and reproduce • Contains the instructions for making specific proteins

  3. DNA Structure • A double helix shape (twisted ladder) • Nucleotide – a molecule made of a nitrogen base, a sugar, and a phosphate group • DNA is made up of nucleotides. • Sugar-phosphate groups form the sides of the ladder • Nitrogen bases form the rungs of the ladder • Adenine (A) – Thymine (T) • Guanine (G) – Cytosine (C) • Replication – the process of copying a DNA molecule to make another DNA molecule when a cell divides

  4. Protein Synthesis • RNA – a type of nucleic acid that carries code for making proteins from the nucleus to the cytoplasm Transcription – the process of making mRNA • Comparing DNA and RNA:

  5. Three Types of RNA • Messenger RNA (mRNA) • DNA “unzips” and mRNA goes in and decodes the bases then brings the code to the ribosomes (where proteins are made in the cell) • Translation – the process of making a protein from RNA • Transfer RNA (tRNA) • Three nitrogen bases (codon) code for an amino acid. The tRNA forms the amino acids. • Ribosomal RNA (rRNA) • Helps bond the amino acids together to form a chain. A chain of amino acids is a protein.

  6. Mutations • Mutation – a change in the nucleotide sequence of a gene due to a mistake during replication • Three Types of Mutations: • Substitution – one nitrogen base is replaced with a different nitrogen base • Insertion – one or more nitrogen bases are added to the DNA • Deletion – one or more nitrogen bases are left out of the DNA

  7. There are 3 possible consequences to changes in DNA (mutations): • An improved trait • No change • A harmful trait • What causes Mutations? • Caused by random errors when DNA is copied. • Caused by physical or chemical agents that change DNA (mutagen) Ex: • High level radiation: X-rays Ultraviolet rays • Asbestos & chemicals in cigarettes

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