Bio 132 (Unit 4 & lab) Exam Updated with Complete Solutions

Bio 132 (Unit 4 & lab) Exam Updated with Complete Solutions explain the 'life came from outside of earth' hypothesis for the origin of life - Answer- some meteorites containing molecules such as purine, pyrimidines, and amino acids collided with earth. Miller and Urey's primitive earth experiment set up - Answer- water, methane, ammonia, and hydrogen sealed in a sterile flask with sparks to emulate lightening and heated water to simulate the ocean What are the four building blocks of life? - Answer- lipids, proteins, nucleic acids, carbohydrates explain the chemical evolution hypothesis for the origin of life - Answer- conditions on primitive earth led to formation of simple molecules which led to life forms How did Miller and Urey separate the results of their experiment - Answer- TLC (thin layer chromatography) What were Miller and Urey's findings - Answer- - 17 of the 20 amino acids for protein synthesis - several different 3 to 6 carbon sugars (carbohydrates) - various fatty acids Many experiments have been conducted to replicate the early conditions of earth to explore the theory that life could have been evolved by inorganic molecules. Name the biological molecules that have components that were observed in these experiments: - Answer- proteins, carbohydrates, lipids, metal catalysts Many experiments have been conducted to replicate the early conditions of earth to explore the theory that life could have been evolved by inorganic molecules. What biological molecule did not have the components observed in these experiments? - Answer- nucleic acids How could polymers have become self replicating? - Answer- the appearance of catalysts (known today as enzymes) what are the two biological molecules that can perform catalysis - Answer- proteins and RNAs Metabolism First Hypothesis (origin of large biomolecules) - Answer- - chemical reactions involving small molecules evolved first (before nucleic acids) - some of these small molecules formed polymers that acted as genetic information and catalysts Genes First Hypothesis (origin of large biomolecules) - Answer- - RNA world hypothesis - the first life forms were self replicating nucleic acids - RNA formed early, acting as both genetic information and a catalyst What is one observation that provides evidence for the role of RNA in the early evolution of life regarding retroviruses? - Answer- Modern day retroviruses contain an enzyme called reverse transcriptase What were the three components that came together to form RNA? - Answer- nitrogenous bases, ribose sugar, and phosphate 5 steps of RNA world hypothesis: - Answer- 1. ribose sugar, nitrogenous bases, and phosphate come together to form RNA 2. Some RNA molecules gain the ability to replicate 3. Some RNA molecules gain the ability to act as catalysis's and make catalytic proteins 4. Catalytic proteins aid in the formation of double stranded RNA which evolves into double stranded DNA 5. DNA becomes the primary genetic material (DNA is more stable) 5 events in early evolution: - Answer- 1. atmosphere consists primarily of CO2, N2, H2 2. spontaneous formation of small organic molecules from inorganic molecules 3. formation of macromolecules (proteins, nucleic acids, lipids, carbohydrates) 4. RNA is the initial genetic system, capable of self replication and catalysis 5. interactions between RNA and amino acids evolved into the genetic code. DNA replaces RNA as the genetic material. What event could have occurred between the existence of the "RNA world" and the evolution of the first cells to help control the cells internal environment - Answer- The rise of lipid bilayer membranes what does compartmentalization allow - Answer- for cells to maintain a chemical composition distinct from the external environment what molecules do protocells allow to pass through the membrane - Answer- sugars and nucleotides what did the first cell likely consist of? - Answer- self replicating RNA and its encoded proteins