BIOLOGY CHP. 12

DISCOVERY OF DNA

• Griffith - did the first major experiment that led to the discovery
• Avery - first to Isolate DNA macromolecules
• Hershey & Chase - Use radioactive labeling to trace the DNA and protein

DNA STRUCTURE

• DNA can be compared to a twisted ladder
• It is called a double helix
• Rails of the ladder are represented by the alternating deoxyribose and phosphate

NUCLEOTIDES

• DNA Nucleotide- contains a sugar-deoxyribose, a phosphate, and one of the nitrogen bases
• RNA Nucleotide - contains a sugar-ribose, a phosphate, and one of the nitrogen bases

NITROGEN BASES

• DNA nucleotides can contain: adenine, guanine, cytosine, or thymine
• RNA nucleotides can contain: adenine, guanine, cytosine, or uracil

THREE MAIN KINDS OF RNA

MESSENGER RNA (mRNA)

• Long strands of RNA nucleotides that are formed complementary to one strand of DNA

RIBOSOMAL RNA (rRNA)

• Associates with proteins to form ribosomes in the cytoplasm

TRANSFER RNA (tRNA)

• Smaller segments of RNA nucleotides that transport amino acids to the ribosome