DNA and Protein Synthesis
Nucleotide
The
Structure
of DNA
DNA’s Four Bases:
Adenine
Thymine
Cytosine
Guanine
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.