Chapter 1

  1. The phrase refers to the fact that all organisms are remarkably similar at a biochemical level, which strongly suggests that all organisms on Earth are derived from a common ancestor.

  2. DNA is double stranded, and its sugar is deoxyribose. DNA contains the base thymine. RNA is usually single stranded, and its sugar is ribose. RNA uses uracil in place of thymine.

  3. Proteins are linear polymers composed from 20 different amino acids. Glycogen is a branched polymer composed only of glucose.

  4. The central dogma describes the fundamental information flow in biological systems. DNA is replicated to form new DNA, which is transcribed into RNA. The RNA is translated into protein.

  5. Replication is the generation of two daughter double helices from a single parent double helix. The process is catalyzed by DNA polymerase. Transcription is the process of copying DNA information into RNA and is catalyzed by RNA polymerase. Translation converts the sequence information of RNA into proteins and takes place on ribosomes.

  6. An enzyme is usually a protein catalyst, although some types of RNA also function as catalysts. Catalysts enhance the rate of a chemical reaction without themselves being permanently altered.

  7. Eukaryotic cells contain a nucleus and a complex of membrane-bounded internal structures called organelles. Prokaryotic cells do not have a nucleus and lack the complex internal organization of eukaryotic cells.

  8. An organelle can be any of a number of membrane-bounded structures inside eukaryotic cells.

  9. Mitochondria, chloroplasts, and nuclei.

  10. The nuclear membrane is not continuous. It is a set of closed membranes that come together at pores.

  11. The gene is transcribed into RNA, which is translated into the protein on ribosomes bound to the endoplasmic reticulum. The protein enters the lumen of the endoplasmic reticulum, is sequestered into transport vesicles, and moves to the Golgi complex, where the protein is modified. The protein is packaged into secretory vesicles that fuse with the plasma membrane, resulting in the exocytosis of the protein.

  12. Complete the interactive matching exercise to see answers.