Chapter 11 - BIO387

Among the oldest fossils on Earth are the microfossils from the Agnes gold mine of South Africa, which are __________ years old.

3.2 billion

Miller and Urey developed and conducted some experiemental test for a "prebiotic soup" model of the origin of life, which had been proposed a few decades earlier by Oparin and Haldane. What did Miller and Urey show could be synthesized abiotically?

Amino acids

In light of recent achievements in the field of genomics, would it be reasonable to expect that the use of comparative genomics might shed light on the extinct genomes of early life?

Comparative genomics and studies of the bacteria with very small genomes do shed light on a common ancestor and researchers can estimate the minimal characteristics that a cell would need to operate as a living organism.

What do we know about horizontal gene transfer in the evolution of early life?

HGT was probably a powerful force during early cell evolution, leading to complex cellular organisms.

The origin of cell structures might be hypothesized to have involved a hypercycle, based on mutualism at the molecular level. Which of the following is correct regarding the hypercycle model?

Natural selection will favor a hypercycle that is enclosed in a membrane.

Which gas was most likely the lesat abundant in early Earth' atmosphere?

O2; Based on evidence from chemistry and physics, CH4, NH3, and H2O might best represent the characteristics of early Earth's atmosphere.

Which two scientsits elaborated on Darwin's idea of the "warm little pond" and formulated the "prebiotic soup hypothesis" as the first hypothesis for the abiotic origin of life on Earth?

Oparin and Haldane

The first genetic material was most likely:

RNA

Which of the following statements about the Lincoln and Joyce experiment on self-replicating ribozymes is most likely correct?

The self-replicating ribozymes that had more efficient catalytic activities would soon began to dominate their populations.

All of the following are true regarding Spiegleman's experiemnt on the origins of life EXCEPT: a. The most common size of RNA in the final test tubes was a little over 200 nucleotides long b. Variation in the length of the strans occured at each round of replication c. There was no selection for any of the variations in length d. Shorter RNA sequences were favored by selection, so long as they were not too short

There was no selection for any of the variations in length

The human parasite Mycoplasma gentialium, with one of the smallest genomes of any organism that can be grown, as well as Chlamydia trachomatis, and obligate intracellular parasite, are examples of the types of organisms that functional genomics researchers have focused on. What is the main purpose of the study of such genomes?

By studying such genomes, researches try to discover that basic and essential cellular functions of early life.

In order to understand the origin of life on Earth, evolutionary biologist collaborate with:

Chemists, geologists, and atmospheric scientists

What is the most relevant hypothesis for the benefit of making the switch from the RNA- to a DNA-based genetic system during the evolution of life?

DNA is a more stable molecule because deoxyribose is less reactive than is ribose.

Which of the following molecules involved in memebrane structures was likely favored by natural selection in the evolution of early cells?

Fatty acids; they were used to construct the membrane that would encase early cells. The multualistic relationship within early cells lead the replicators to be more productive in fatty acid production and forming enclosed memebrane bound systems.

In 1977 Sidney Fox tried a different approach to testing the prebiotic synthesis of biological molecules. He mixed a number of different amino acids together at a high temperature (120°C) in an environment lacking water. When he subsequently placed the mixture into water to investigate what the amino acids would form, he:

Found some peptide-like structures, but the bonds between the amino acids were weak and unstable; Subsequent work by Claudia Huber and her colleagues found that amino acids do link together via stable peptide bonds in the presence of a compound such as carbon monoxide (CO), which is thought to have been present in early Earth's atmosphere

Which of the following statements about LUCA is NOT correct? a. The acronym stands for "last universal common ancestor." b. It represents a base to the tree of life. c. It is meant to be a single organism. d. It represents a phylogenetic event horizon.

c. It is meant to be a single organism