Exam 4: Nucleic Acids and the Origin of Life

In modern microbiology laboratories, scientists use sterile pipettes to transfer liquid cultures of microorganisms from one flask to another.The pipettes are sterilized by heating at very high temperatures, followed by cooling before use.Using sterile technique allows microbiologists to be confident that their cultures contain only the microorganisms that they want to work with and no others.This is possible because using sterile technique is an application of Pasteur's experiment in which he proved that living organisms do not arise by _______ from nonliving matter.

When J.William Schopf observed chains and clumps that resembled modern cyanobacteria in Australian sedimentary rocks, he concluded that these were remains of living organisms because

Miller and Urey found that several different amino acids were formed during their first experiment using heated gases treated with electric sparks.The gas _______ was likely responsible for providing the source of nitrogen atoms that ended up in these amino acids, and water vapor was the likely source of oxygen atoms in these same molecules.

Scientists have generated protocells under lab conditions using different combinations of fatty acids.They have found that branched but not straight-chain fatty acids allow nucleotides to pass into protocells from the surrounding environment.Why is this an important finding in the study of the evolution of life?

The figure shows a cut away view of a structure used in experiments investigating the evolution of life on Earth. These experiments were pivotal in finding evidence for the emergence of cells as the fundamental unit of life, because they focused on how a primitive _______ was able to form, creating a barrier between internal and external environments.

Why did the Miller‒Urey hot chemistry experiment exclude oxygen in its investigation of the chemical origin of life on Earth?

In a DNA double helix, a given purine can be paired with

In experiments measuring the rates at which different monosaccharides diffuse across phospholipid membranes, it was found that the rates followed this pattern (from slowest to fastest): glucose < mannose < arabinose < xylose < ribose.What aspect of the current theories about the origin of life do these results support?

Single-stranded RNA can fold back on itself, creating three-dimensional structures such as tRNA.The folds are stabilized by _______ bonds.

Retroviruses, such as HIV, have an enzyme that allows them to catalyze DNA synthesis from an RNA template.This evidence supports the hypothesis that

In DNA, bonding of A with T and bonding of C with G are examples of

In the first Miller-Urey experiment, an electrical spark was passed through an experimental "atmosphere" consisting of hydrogen gas, ammonia, methane gas, and water vapor.A limitation of this experiment was that it

Refer to the figure below illustrating Louis Pasteur's experiment on spontaneous generation. The experiment supports which hypothesis?

Changes to the original Miller‒Urey hot chemistry experiment included adding other gases like carbon dioxide (CO₂), nitrogen (N₂), hydrogen sulfide (H₂S), and sulfur dioxide (SO₂) in the test apparatus, which resulted in the production of more small molecules of life than the original experiment had produced.Which products were shown to be significant for the synthesis of proteins?

Many enzymes in organisms living today have metal cofactors such as iron or zinc that participate directly in the reactions they catalyze.How might this property reflect the evolution of catalysts in living organisms, reaching all the way back to prebiotic times before living cells arose?

Why was the evolution of a self-contained cell essential for life as we know it?

When fatty acid molecules are in water, they can self-organize into a bilayer (double layer) that surrounds an inner core of water.Where "middle" refers to the middle of the bilayer between the outer and inner layers of fatty acids, which of the following statements is correct?

One way that modern enzymes increase reaction rates is to increase the chance for collision between molecules by binding them in close proximity to each other.Enzymes also increase rates by orienting reacting molecules in three-dimensional space to facilitate attack of one substrate by another.The figure below shows an organic molecule adsorbing onto a clay mineral surface. How do the properties of enzymes mentioned above relate to the way that clay minerals are hypothesized to have been instrumental in the rise of life?

A woman buys a fresh loaf of bread wrapped in a plastic bag.She removes several slices of the bread and closes the bag tightly before storing the bread in her pantry.When she takes the loaf out several days later, she is dismayed to see mold growing on the bread.She recognizes that mold spores must have landed on the bread before she closed the bag for storage in her pantry, because she knows that living organisms do not arise through _______.

The original Miller-Urey experiment did not include several gasses later shown to have occurred on the primordial Earth, including CO₂, N₂, and SO₂. When scientists ran a new experiment incorporating these gasses, which of the following was not produced?