DNA: The Molecule of Heredity Chapter 11.1

I. THE BUILDING BLOCK OF DNA Nucleotide –Sugar –Phosphate group –Nitrogen base (nitrogenous base)

II. WHAT IS DNA? Your “genetic material” “codes” for the production of proteins –Skin, hair, nails, bones, muscles, enzymes “Hershey/Chase” = DNA is your genetic material

III. STRUCTURE OF A NUCLEOTIDE Sugar Phosphate Group Nitrogenous Base (Nitrogen Base) –A (adenine) –T (thymine) –C (cytosine) –G (guanine)

III. STRUCTURE OF A NUCLEOTIDE

III. STRUCTURE OF NUCLEOTIDES Nucleotides form long chains or strands to create a DNA molecule Backbone consists of the phosphate groups and deoxyribose Nitrogen base pairs are “steps” in the twister DNA ladder

STRUCTURE OF DNA

IV. STRUCTURE OF DNA Watson and Crick first published the structure of DNA –“Double Helix” 2 strands of nucleotides held together by the nitrogen bases’ HYDROGEN BONDS –Bonds between A:T, C:G

V. THE IMPORTANCE OF NUCLEOTIDE SEQUENCES Key to “variety” in the species on Earth Different “sequences” make different organisms –ATTGAC (chimpanzee) –ATTGAG (human) –ACGGTA (rat)

DNA STRUCTURE AND REPLICATION

VI. REPLICATION OF DNA From “one” fertilized cell, millions are produced through “mitosis” Each new cell has a copy of the “DNA” that was in the original fertilized egg. The process that provides that is: –“DNA Replication”: when the DNA in the “nucleus” of a cell are copied Usually during interphase

VI. REPLICATION OF DNA If we didn’t do this, we would have ½ our DNA –species wouldn’t survive All organisms replicate their DNA

VII. HOW DOES DNA REPLICATE 2 strands “UNZIP” and separate (break “hydrogen bonds”) Free floating nucleotides attach to the 2 original/parent strands Parent DNA continues to unzip until all are paired with free floating nucleotide When all DNA and chromosomes are replicated, the cell can divide, passing on the genetic information to the new cell