DNA and Protein Synthesis

The Structure of DNA

Nucleotide

DNA’s Four Bases:

AdenineThymineCytosineGuanine

The Base Pairing Principle

• Because of the number of hydrogen bonds between them (2 & 3), it is only possible for thymine to pair with adenine, and guanine with cytosine.

Protein Synthesis

• The DNA code serves as a blueprint for making specific proteins.

• Examples of proteins: hormones, enzymes, neurotransmitters, receptors, components of tissue.

• Proteins are composed of amino acids.• Codons are a sequence of three bases that

code for a specific amino acid.

Transcription

Messenger RNA can leave the nucleus via a nuclear pore.

Translation

Transfer RNA

Proteins and Genes

• The tissues that constitute your body are complexes of proteins. For instance, skin is composed of the proteins collagen, keratin, and elastin. Since a number genes are involved in making this tissue, we say that the trait is polygenic.

• Elastin is found in many of the bodies’ tissues. If something happens to this gene, the effects will be observed in all tissues where this protein occurs. The effect will be pleiotropic.

Example: William’s syndrome is a disorder caused by the deletion of 26 genes from chromosome 7. Among the genes deleted is the ELN gene for making elastin. The result is both connective tissue and cardiovascular problems.