Transcript How does a gene encode your characteristics?

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