S ECTION 4.4 CELLS USE DNA AND RNA TO MAKE PROTEINS Objectives: How the structure of DNA stores information the cell needs How RNA is copied How RNA uses the information from DNA to make proteins

W HAT IS DNA ? DNA (Deoxyribonucleic Acid) - is a molecule that stores information that is needed to produce inherited traits.

P ROTEINS AND AMINO ACIDS Proteins are large molecules that are made up of chains of amino acids 20 different amino acids combine in many ways that make up the thousands of different proteins

E XAMPLES OF PROTEINS LYSOZYME is a small protein that kills bacteria DYSTROPHIN a huge protein in muscle cells

W HAT ARE AMINO ACIDS ? In order to produce a specific protein, cell needs the right sequence of amino acids. DNA stores the information that the cell needs to make each protein.

NUCLEOTIDES DNA and RNA are made up of smaller pieces called nucleotides. This pieces make up the side rails of the DNA ladder. Types: ADENINE THYMINE CYTOSINE GUANINE (All Tigers Can Growl)

REPLICATION Interphase – DNA is loose in the Nucleus. Before the cell divides, its DNA is copied. STEPS: 1. The DNA molecule opens up, separating into two strands 2. Nucleotides match up and join to the open DNA strands 3. Two identical DNA molecules are formed

W HAT IS RNA? RIBONUCLEIC ACID uses the DNA’s sequence of bases to link amino acids into chains that form proteins RNA is the way the cell connects the code of DNA bases into the chains of amino acids needed to make proteins DNA BASES C – G and A – T RNA BASES C – G and A - U

TYPES OF RNA mRNA - messenger tRNA - transfer rRNA - ribosomal

TRANSCRIPTION The process of transferring information from DNA to mRNA RNA base pairs: C – G; A – U STEPS: DNA is used as a template and only one strand of DNA is transcribed. Nucleotides of RNA match up and join to the open DNA strand The completed mRNA strand is released and moves into the cytoplasm

TRANSLATION To make a protein, a cell must translate the nucleotide bases into the language of amino acids. Translation occurs in the cytoplasm of a cell and it involves mRNA, tRNA and rRNA Proteins are made on ribosomes (structures that are made up of RNA and proteins)

S TEPS 1. A ribosome attaches to an mRNA molecule at the beginning of a coding region 2. tRNA matches up and joins to the mRNA strand 3. As the ribosome moves along the mRNA, it attaches one amino acid to another

4. The tRNA molecule is released after its amino acid has been attached to the chain. 5. Once the ribosome reaches the end of the coding region, the completed chain of amino acids is released.