[LIFESCI 3] - Midterm Exam Guide - Comprehensive Notes for the exam (23 pages long!)
Document Summary
Molecular biology: the study of essential macromolecules. Prokaryotic cells have no membrane bound organelles and no nucleus. Dna is usually in a circle floating freely around cell. Eukaryotic cells are more complex with a nucleus holding dna. Nucleotide: sugar + phosphate + nitrogenous base. Deoxyribose (in dna) vs. ribose (in rna) Deoxyribose: has a h attached to the 2" carbon. Ribose: has a hydroxyl group (oh) attached to the 2" carbon. Phosphate on 5" carbon of nucleotide is attacked by oh on 3" carbon of the strand. Adenine pairs with thymine; guanine pairs with cytosine. Adenine and thymine have two hydrogen bonds. Guanine and cytosine have three hydrogen bonds. Hydrophobic effect and pi bond stacking influence the orientation of bases which causes the helical shape in dna. Covalent bonds occur between the sugar and phosphate groups in the backbone. Hydrogen bonds hold together two strands of dna.
