DNA Deoxyribonucleic acid DNA determines an organisms traits

DNA Deoxyribonucleic acid

» DNA determines an organism’s traits » it does this by controlling the production of proteins/enzymes » all actions: running, thinking, eating, etc. ; depend on enzymes to run the chemical reactions required

DNA Structure » DNA forms a double helix 2 strands twisted together » looks like twisted zipper » DNA is composed of repeating units called nucleotides

» nucleotides have 3 parts: » A simple sugar ˃ in DNA: deoxyribose » A phosphate group » A nitrogen base

» Four nitrogen bases in DNA » Adenine - A » Thymine - T » Guanine - G » Cytosine - C

» Sugars and phosphate groups form the backbone of the DNA » The nitrogen bases attach between the double-helix » Adenine only attaches to Thymine » Guanine to cytosine

» The arrangement of these bases forms the code for all the proteins produced in our bodies » DNA has the same structure in all organisms; only the bases are arranged differently

» DNA Replication » before cells can divide, the DNA must be copied » When a cell prepares to copy the DNA, the hydrogen bonds (weak) between nitrogen bases are broken

» The DNA then “unzips” » this exposes the bases

» free nucleotides in the nucleus pair with the exposed bases » A - T » C - G

» The sugars and phosphate groups bond to form a new backbone » produces two identical strands of DNA » each has one original parent strand a new daughter strand