Nucleic Acids Organic compounds found in the nucleus of living cells. They store information that directs the activities of a cell by guiding the formation of both structural and enzymatic proteins. Because nucleic acids contain the information necessary for the manufacture of the organism’s proteins, they also determine its characteristics. DNA (deoxyribonucleic acid) ~ the primary nucleic acid in most organisms. It contains the information that is needed for almost all of a cell’s activities. Contains your genes. Replication ~ the process by which a DNA molecule “unzips” so that free nucleotides that are in the cell can come and rebuild the missing half of the molecule. This results in 2 new identical DNA molecules forming from the original one.

DNA molecule = Sentence Genes = Words Nucleotides (with different bases) = Letters

Nucleotides Monomers of nucleic acids are nucleotides, which are composed of 3 components: Sugar ~ the 5 carbon sugar deoxyribose Phosphate ~ small molecule made of phosphorus & oxygen atoms Base ~ each nucleotide will have one of the following bases: adenine, guanine, cytosine or thymine. Adenine will bond only with thymine. Guanine will bond only with cytosine. Nucleotides are put together by dehydration synthesis.

Starch granules in potato tuber cells Starch Figure 3.7 Starch granules in potato tuber cells Starch Glucose monomer Glycogen granules in muscle tissue Glycogen Cellulose microfibrils in a plant cell wall Cellulose Figure 3.7 Polysaccharides Hydrogen bonds Cellulose molecules 7

Discovering the Structure of DNA James Watson and Francis Crick ~ identified the structure of the DNA model in 1953. They referred to the shape as a double helix, which resembles a twisted ladder.

RNA Ribonucleic acid ~ the basic nucleic acid in some viruses, but important to all living things. 3 Differences between RNA and DNA Contains ribose instead of deoxyribose Contains the same nitrogen bases as DNA except uracil replaces thymine It’s single stranded instead of double stranded mRNA (messenger RNA) is a type of RNA that codes for specific amino acid sequences which makeup proteins. RNA is formed by Transcription ~ the process in which a DNA molecule will unzip and the proper nucleotides come and rebuild the missing half, but after forming, will detach from the DNA molecule. The DNA molecule will then “zip” back together.