THE INSTRUCTION MANUEL FOR BUILDING A BODY DNA

THE INSTRUCTION MANUEL FOR BUILDING A BODY

DNA stands for Deoxyribonucleic Acid and is the basic substance of heredity. http: //www. thetech. org/exhibits_events/online/genome/index 2 a. html DNA is a set of instructions for building your body and controls everything about the way you look and function.

WHERE IS THE DNA STORED? The DNA is stored in the nucleus of nearly all your cells. Watch as we trace the path to locate our DNA http: //www. thetech. org/exhibits_events/online/genome/index 3. html

Who has more? Eukaryotic cells contain more DNA than prokaryotic cells. Makes sense: They are larger and have more “stuff” in them that need instructions!

What does DNA look like? http: //www. thetech. org/exhibits_events/online/genome/DNA 5. html A little history Watson & Crick found through X-ray images, that DNA looks like two threads twisted around each other & held together by many bridges in between, like a spiral staircase. This structure is called a double helix. These scientists won a Nobel Prize in 1962 for work on the DNA’s structure. Rosalind Franklin was actually the 1 st scientist to produce the pictures of DNA , but died before the Nobel Prize was given.

The Parts of DNA • • DNA is made up of NUCLEOTIDES are made of three parts: 1. A Pentose Sugar: Deoxyribose…it’s a sugar with 5 carbons (penta=5, -ose=sugar). 2. A Phosphate Group 3. One of four different Nitrogenous Bases: Adenine Thymine Cytosine Guanine A T C G

Visuals of the THREE Parts of a nucleotide: Nitrogenous base Pentose Sugar Phosphate group

The DNA “Double Helix” Molecule Looks like a twisted ladder The sides of the ladder are made of sugar molecules and phosphates The steps of the ladder are formed by pairs of nitrogenous bases

Nitrogenous bases There are four different nitrogenous bases • Adenine A • Thymine T • Guanine G • Cytosine C • Adenine always pairs with Thymine and Guanine always pairs with Cytosine • The genetic code is the order of the nitrogenous bases and the set of instructions for making a person. • This is known as the HUMAN GENOME

example ATTCGAACGACCTG TAAGCTTGCTGGAC Try your own: GTAACTGGAACTAG CATTGACCTTGATC

Genes are… • A GENE is a set of chemical instructions for assembling a protein. DNA is the molecule that carries these genetic instructions. • Within a gene, each group of three nitrogenous bases codes for one amino acid. • A sequence of amino acids is linked to make a protein. • *Therefore, the way N bases are arranged, determines the order in which amino acids are put together. The arrangement of amino acids makes a particular protein. • Proteins are fundamental to the function of cells and the expression of traits.

What is a genetic code? • The genetic code is the set of rules by which information encoded in DNA is translated into proteins by living cells. • The code defines how sequences of three nucleotides specify which amino acid will be added next during protein synthesis. • The order of the bases tell the cell what types of proteins to make! • The genetic code is the specific order and number of nitrogen bases of an organism’s DNA!

DNA Replication n A cell must copy its DNA during the S phase of Interphase of the cell cycle. n Replication – process of copying DNA; Occurs in the nucleus. n. How it works: 1. DNA helicase unzips the DNA by breaking the H bonds. 2. DNA polymerase enzyme attaches free DNA nucleotides to make 2 new DNA strands. After replication: Each new DNA molecule has one old strand one new strand.