How does DNA encode your characteristics?

Your characteristics are determined by proteins.How? Let’s look at a simple example:• Jonny’s hair is blond –why?

– Hair color is determined by pigments, which are fats and are created in a chemical reaction in the cells of skin and other hair follicles. Enzymes in those cells tell how much of the pigment will be produced. Jonny’s cells produce less of the enzyme, which means less pigment is produced and his hair stays light in color.

Enzymes are Proteins

• Which are long folded chains of amino acids.

• Other things proteins do that effect your characteristics are:– Transporters of things like oxygen– Membrane Channels which let things in and out

of cells (all of your senses and thoughts are nothing more than many cells receiving specific chemical signals)

So where does DNA fit in?

• Genes– Sections of chromosome (DNA) that have

information for a building PROTEIN.

Proteins are built at the ribosomes

• But the information for building them is in the NUCLEUS.

• The cell has 2 molecules that helps bring the information and the amino acids to the ribosome:– Messenger RNA– Transfer RNA

What is RNA? (Ribonucleic acid)

How is it different from DNA?

• Single stranded

• Contains the sugar ribose instead of deoxyribose.

• Uses Uracil instead of Thymine

What do the two RNA’s do?

Overview of protein synthesis

• Genes in DNA are copied by messenger RNA called TRANSCRIPTION

• Messenger RNA is read at the RIBOSOME by transfer RNA that carries AMINO ACIDS to be assembled into a protein called TRANSLATION