1. DNA

2. 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

5. 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: DNARNA Double-strandedSingle-stranded ThymineUracil

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

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

8. There are 3 possible consequences to changes in DNA (mutations): 1.An improved trait 2.No change 3.A harmful trait What causes Mutations? 1.Caused by random errors when DNA is copied. 2.Caused by physical or chemical agents that change DNA (mutagen) Ex:  High level radiation: X-rays Ultraviolet rays  Asbestos & chemicals in cigarettes