Oxygen and Life Essay

When life arose on Earth about 4 billion years ago, the first types of cells to evolve were prokaryotic cells. For approximately 2 billion years, prokaryotic-type cells were the only form of life on Earth. The oldest known sedimentary rocks found in Greenland are about 3.8 billion years old. The oldest known fossils are prokaryotic cells, 3.5 billion years in age, found in Western Australia and South Africa. The nature of these fossils, and the chemical composition of the rocks in which they are found, indicates that these first cells made use of simple chemical reactions to produce energy for their metabolism and growth. Eukaryotic cells evolved into being between 1.5 and 2 billion years ago. Eukaryotic cells appear to have arisen from prokaryotic cells, specifically out of the archaea. Indeed, there are many similarities in molecular biology of contemporary archaea and eukaryotes. However, the origin of the eukaryotic organelles, specifically chloroplasts and mitochondria, is explained by evolutionary associations between primitive nucleated cells and certain respiratory and photosynthetic bacteria, which led to the development of these organelles and the associated explosion of eukaryotic diversity. Today Prokaryotes

6. The atmosphere of early earth primarily may have consisted of a reducing atmosphere thick with water vapor, along with nitrogen and its oxides, carbon dioxide, methane, ammonia, hydrogen, and hydrogen sulfide.

Describe the important chemistry of early earth and how this may have given rise to life forms.

Proteins are complex structures made up of chains of amino acids. Each protein has a different function such as enzymes to catalyze reactions or protein hormones to trigger certain functions of a cell. First let’s start with the most basic component of a protein: an amino acid. An amino acid is made up of a central carbon atom attached to a hydrogen atom, a carboxyl group, an amino group, and an R group which varies

The cell is the basic unit of life and is the smallest, simplest organism that can perform all of life’s functions. The cell was discovered in 1665 by Robert Hooke. The three types of cells are plant cells, animal cells, and prokaryotic cells. These cells share many qualities but are also different in many ways.

Ribosomes then started copy themselves into cell-like structure with a thin membrane and cytoplasm. Eventually, cells starting storing DNA. Lateral transfer diversified the cells genetic makeup. From this community of cells came the three domains, known as bacteria, eukaryotes, and archaea. Bacteria and archaea are together called

The cells are the basic units of life. Cells contain DNA that make up genes. Genes are

1. List the qualities (at least 6) that define life AND discuss how a single-celled organism, such as an Amoeba or a yeast cell, and a more complex one, such as a tree or a cat, matches up with each characteristic

Current geological indicators suggest that parts of Earth’s crust had already solidified by 4.4 billion years ago, which is not long before oxygen started showing up in ancient rocks. Furthermore, other microfossils (or chemical evidence suggesting their presence) have been discovered in the past year by research scientists, and possibly date as far back as 4.28 billion years ago.

Although both abiotic synthesis and the deep-sea vent hypotheses argue the environment of a primordial-Earth was required for the origin of life, the two hypotheses have their differences. In general, the abiotic synthesis hypothesis describes the process of how organic compounds can be created from inorganic compounds, while the deep-sea vent hypothesis argues a possible scenario where life may have originated from inorganic compounds. While the term “primordial soup” has been used to describe abiotic synthesis, the same term has been used to describe the extreme environment surrounding hydrothermal vents. In Stanley Miller’s experiment, Bada and Lazcano (2008, p.745) argue, Miller showed abiotic synthesis took place by introducing an electric current to a circulating mixture of pressurized “CH4, NH3, H20, and H2.” However, samples of both types of hydrothermal vents show different mixtures than that of Miller’s experiment. Although the LCHF lacks CO2, according to William Martin, John Baross, Deborah Kelley, and Michael J. Russell (2008, p.806) the compound was not used in Miller’s experiment, but the vent did release ample amounts of H2 and CH4, which were used in Miller’s experiment. Black smokers, on the other hand, give off H2, but also release CO2 and H2S (Martin et al., 2008, p.806). The two hypotheses agree that life on Earth originated around roughly 3.8 billion years ago. Another similarity between the two hypotheses is both argue the precursors of life are

The oxygen revolution: During the Proterozoic, biotic system were being established, which gave rise to biomass of the prokaryotic organisms like the “benthic and planktonic photosynthesizing organisms” Due to the vast developing diversity of environment, organisms could well adapt to these various environments, which increased the input of oxygen on Earth. Hence, in order for the oxygen to be accumulated in the atmosphere, Iron and Sulfur like oxygen-sinks had to be depleted.

The two theories for the emergence of metabolism and polymers are catalytic changes that make metabolism first and the replication by nucleic acids before metabolism. The metabolism first theory is when life came to be by tiny droplets undergoing chemical changes, which concentrated the content of the tiny droplets. A mineral called pyrite may have been an energy source for polymerization reactions as well as the eventually forming nucleic acids and proteins. After the metabolism was created then nucleic acid replication as well as enzymatic function may have been evolved. The second theory is that nucleic acids evolved first. Random polymers had the function to produce proteins and replicate. This had issues because of the inability to reproduce as well as DNA is not self-catalytic. On the other hand the theory could be possible due to the

Life arose on Earth around four billion years ago, but under conditions that are strikingly different from those on Earth today. The terrestrial atmosphere, now rich in molecular oxygen, was not before oxygenic photosynthesis. The chemistries possible at the time that life began cannot be assumed to occur spontaneously on Earth today, nor can chemistry that happens spontaneously today be expected to have been favored four billion years ago. Thus, it is important to understand the possible abiotic chemistries in the context of early Earth environments, as these environments may be occurring today on places like Jupiter's moon Europa or Saturn's moon

The cell is the smallest unit able to sustain life, and they are often referred to as the building blocks of life. There are two primary types of cell, which are categorized according to the way their genetic material is packaged, rather than size or shape. These are:

percent by weight of the oceans and, as a constituent of most rocks and minerals,