Lecture 19

Front 1

What are the 4 stages we discussed in the development of life on the planet?

Back 1

1) Abiotic synthesis and accumulation of small organic molecules, 2) Polymerization of monomers into large macromolecules, 3) Aggregation and isolation of macromolecules into independent units, 4) Development of a mechanism of heredity

Front 2

Discuss the role of the composition of Earth's primordial atmosphere in facilitating the spontaneous development of life. Do these same conditions exist now? Why or why not?

Back 2

Was a reducing atmosphere; allowed complex molecules to form and accumulate. Because of this, the Earth was bombarded by high levels of lightning and ultraviolet radiation, which could have provided the energy needed for chemical reactions to occur. These conditions don't exist now; we have an oxidizing atmosphere = plentiful oxygen, breakdown of complex molecules.

Front 3

Discuss the implications of current atmospheric composition for the spontaneous creation of life.

Back 3

Life could've risen independently of the atmosphere, or amino acids could've been derived from extraterrestrial sources like meteorites.

Front 4

What is chemical evolution and how does it compare to biological evolution?

Back 4

Chemical evolution is this process by which the building blocks of life evolved into humans; biological evolution is the nat. selection of life?

Front 5

What was the purpose of the experiment performed by Miller and Urey? What was the general design of their experiment and what were the major conclusions? What changes have more recent researchers made to Miller and Urey's original design? What have these new studies concluded?

Back 5

The purpose was to discover whether or not the building blocks of life could spontaneously arise under the proper conditions. The conditions were likely not those found on pre-life earth. However, they found that under some conditions indeed they did arise spontaneously. New researchers think that life may have arisen independent of the atmosphere or through extraterrestrial ways such as a meteorite.

Front 6

What are the major hypotheses we discussed for the site of the origin of life? Do they all involve life evolving here on Earth? Explain.

Back 6

Clay particles? No, they also involve the possibility of meteorites (which contain organic compounds) or benthic hydrothermal vents.

Front 7

What is a polymer? Provide at least one example of a polymer found in organisms. What significance does the process of polymerization have for biology and the origin of life?

Back 7

A polymer is a chain of monomers (i.e., nucleic acids, polysaccharides, etc.). One example = nucleic acids. Creates macromolecules and puts together the building blocks of life.

Front 8

What is a protobiont and what is the significance of protobionts in explaining the development of life? Are protobionts actual primitive cells? What types of features can protobionts possess that are of significance in understanding the origin of life?

Back 8

Protobiont = repeatable pattern of abiotically produced macromolecules. These are important because they create an internal environment different from the surrounding environment. Some forms show basic attributes of living cells. Some features of significance include the internal environment, electrochemical gradient & selective permeability.

Front 9

What two features of RNA are of particular significance for the evolution of life? Explain how these characteristics allowed "populations" of RNA molecules to "evolve."

Back 9

RNA can be catalytic, and it can exhibit differential reproduction. RNA has a three-dimensional shape; different RNA sequences would be more stable in different conditions, and thus favored.

Front 10

Discuss briefly some of the evidence that "populations" of RNA molecules can "evolve"

Back 10

RNA could have begun to be sites of polypeptide synthesis. RNA molecules have 3-dimensional shapes based on their nucleotide sequence.

Front 11

Explain the process of molecular cooperation that could have led to the eventual development of the central dogma of molecular biology.

Back 11

RNA molecules begin to be sites of polypeptide synthesis; DNA may have been formed by RNA sticking together, and favored; we now have what looks like the beginnings of a cell.