DNA- Deoxyribonucleic Acid

Nucleotide- subunit of DNA

composed of

a.  sugar (deoxyribose)

b. phosphate

c.  nitrogen base

     Base pairs-    Adenine(A) pairs with Thymine(T)     and      Guanine(G) pairs with Cytosine(C)

DNA (lives in nucleus)

- carries all hereditary information

- gene- segment of DNA that controls the production of proteins

- two long nucleotide chains in the shape of a double helix, twisted ladder

DNA Replication- DNA making a copy of itself before starting mitosis or meiosis.  The twisted ladder, acts like a zipper, unzips and each half of the zipper is given a new

When going through mitosis the entire genome is copies, when making a protein, only a small section of the genome (DNA) is copied.  This is called a gene.(genes are sections of DNA that code for certain proteins)

DNA Strand 1 TAG GCT ACG

DNA Strand 2 ATC CGA TGC

RNA- Ribonucleic Acid, serves as a copy of DNA that can venture outside the nucleus to make proteins.

DNA Strand 1                                                          GCT CCA  ATG CTA

Complementary messanger RNA (mRNA) Strand                 CGA GGU UAC GAU

Chromosome → DNA (and protein)→ Gene → Nucleotide

Mutation- any change in the genetic code

        Mutagen- substance that causes a mutation (sun, smoke, chemicals, etc.)

1.  DNA Mutation

        A. Point Mutation- a change in a single base pair

                Original    ATT GCC CTA CCG

                Mutated   ATT GCC CTA CTG

        B. Frameshift Mutation- single base is added or deleted

                Original    ATT GCC CTA CCG

ex.            ATT GCC CAC CG        Deletion

                ex.            ATT GCC CTA GCC G  Addition

2.  Chromosome Mutation- Where section of the chromosomes are incorrect (rather than just a single letter or two)

4 types

        1. Addition/Duplication

        2. Deletion

        3. Inversion

        4. Translocation

3.  Nondisjunction Mutation

        -  both members of pair of homologous chromosomes fail to move apart properly resulting in an extra chromosome or one missing chromosome in a egg or sperm.

ex. Down’s Syndrome