CHAPTER 4 Flashcards

Question

describe the experiment

Answer 1

jar 1: meat was exposed to air and flies. maggots formed in the meat jar 2: fine cloth covering jar meat was exposed to air but not flies. no maggots formed jar 3: lid coving jar, meat was no exposed to air or flies. no maggots formed

Answer 2

1. chemical evolution 2. life came from outside earth

Answer 3

-conditions on primitive earth led to information of simple molecules such as amino acids, which led to formation of life forms -Miller and Urey (1950s) experimented with reconstructing those primitive conditions using gases thought to be in the early atmosphere: H2, NH3, CH4, H2O

Answer 4

-volcanoes many also have added CO2, N2, H2C, and SO2 to the atmosphere -adding these gases to the experimental atmosphere results in formation of many more small organic molecules

Answer 5

-some meteorites contain molecule such as purines, pyrimidines, and amino acids, suggesting that living organisms might have reached earth within a meteorite -some question if organisms could survive in a meteorite

Answer 6

-possible conditions including powdered clays, hydrothermal vents, and hot pools (similar to early earth conditions)

Answer 7

-the appearance of catalysts (today catalysts are proteins called enzymes) -proteins are synthesized from information in nucleic acids

Answer 8

-RNA may have been the first catalyst; which is a nucleic acid -the 3D shape and other properties of some TNA molecules (ribozymes) are similar to enzymes -RNA could have acted as a catalyst for its own replication and for synthesis of proteins. -DNA could eventually have evolved from RNA

Answer 9

-ribose can be formed in prebiotic chemical synthesis experiments -peptide linkages are catalyzed by ribozymes today -in retroviruses, reverse transcriptase catalyzes synthesis of DNA from NRA -short, naturally occurring RNA molecules catalyze polymerization of nucleotides in experimental settings -an artificial ribozyme has been developed that can catalyze assembly of short RNAs into a longer molecule that is an exact copy of itself

Answer 10

life must have been concentrated in a compartment -living cells now are separated from their environment by a membrane

Answer 11

-allows cells to maintain a chemical composition that is different from the external environment

Answer 12

they form a lipid bilayer around a liquid compartment

Answer 13

A self-organized sphere of lipids proposed as a stepping-stone to the origin of life; these allow small molecules such as sugar and nucleotides to pas through

Answer 14

if short nucleic acid strands capable of self replication are placed inside protocells, nucleotides can pass through the bilayer and e incorporated into polynucleotide chains

Answer 15

-they are organized systems of parts with substances interacting, in some cases catalytically -the interior is distinct from the exterior environment -capable of limited replication

Answer 16

based on fossil evidence found in Australia cyanobacteria which are single celled algae that photsynthesize which means carbon was needed; since carbon has isotopes it a good way to date things

Answer 17

-carbon isotopes indicative of photosynthesis were found I the fossils and also showed that several other types of bacteria were present as well -probably took 500million to 1billion years for the first cells to appear on earth

CHAPTER 4 Flashcards

(41 cards)