The Genetic Code and Protein Synthesis

Genes and the Genetic Code Gene: a segment of DNA on a chromosomes that codes for a specific trait Genetic Code: formed by the order of nitrogen bases along a gene that specifies what type of protein will be produced

How cells make proteins A cell uses the coded information from a segment of DNA (gene) to make a specific protein Why make proteins? – Proteins determine your traits, hair color, eye color, tongue rolling ability, etc. Things that are not traits: athletic ability

What Protein Synthesis involves: – DNA found in the nucleus – Ribosome: where the proteins are made – RNA (see below) – Amino acids: these are the building blocks of proteins

RNA Similar to DNA Structure of RNA: 1. Sugar is different 2. Single-stranded 3. Uracil replaces thymine 4. Still has cytosine (C), guanine (G), and adenine (A)

Draw me under DNA Draw me under RNA

2 Types of RNA 1. mRNA: messenger RNA – Copies the coded message from the DNA in the nucleus and carries the message to the ribosome in the cytoplasm 2. tRNA: transfer RNA – Picks up and transfers amino acids in the cytoplasm to the ribosome and adds them to the growing proteins

DNA RNA

The Steps of Protein Synthesis 1. In the nucleus, DNA serves as a pattern for making mRNA

2. The DNA molecule unzips and RNA bases match up along one strand of the DNA. This transfers the information from the DNA to the mRNA strand Each group of 3 bases on the mRNA codes for one amino acid

RNA DNA RNA polymerase Steps 1 and 2 Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only)

3. The mRNA moves out of the nucleus and attaches to the ribosome, where protein chain production begins 4. tRNA attaches to the mRNA, and reads the mRNA code

5. If the tRNA matches the code on the mRNA, it drops off its amino acid 6. The amino acids are joined to make a protein

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