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Origin of Life Prokaryotes & Protist
Transcript of Origin of Life Prokaryotes & Protist
in the biosphere minority of prokaryotes: serious illnesses:
Boubonic Plague, tuberculosis, cholera, and STD's majority: produce vitamins recycle carbon earliest organisms on Earth Life on Earth originaged
between 3.5 and 4.0 years ago Live among each other Live symbiotically with eukaryotes 5,000 known species estimated 40,000 species The oldest fossils 3.5 bya and were found embedded in rocks from western Australia. 2 main branches of evolution Bacteria Archaea extreme environments dominated evolutionary history from 3.5 to 2.0 bya.
Two branches- bacteria and archea diverged
Oldest fossils found in stromatolites
Fossils also discoved in Hydrothermal vents
Most prokaryotes are unicellular Structure, Function, and Reproduction of Prokaryotes Protists eukaryotes much more complex microscopic organisms common shapes are:
and helices Nearly all prokaryotes have a cell wall external to the plasma membrane Cell wall maintains shape and provides physical protection. bacterial cells contain peptidoglycan split into as many as 20 seperate kingdoms Cyanobacteria, photosynthetic prokaryotes that generate oxygen, evolved 2.7 bya.
Banded iron formations are evidence of the vintage of oxygenic photosynthesis. cell walls of archaea lack peptidoglycan most nutritionally diverse of all eukaryotes aerobic, with mitochondria for cellular respiration photoautotrophs with chloroplasts heterotrophs that absorb inorganic molecules . mixotrophs, combining photosynthesis and heterotrophic nutrition. mixotrophs, combining photosynthesis and heterotrophic nutrition. mixotrophs that combine photosynthesis and heterotrophic nutrition Began by 2.1 billion years ago
larger and more complex than prokaryotes Movement Multicellular eukaryotes evolved by 1.2 billion years ago
Oldest fossils were relatively small algae about 1.2 bya
Larger ones didn't appear untill about 600 million years ago flagella Prokaryotes may also have smaller rings of DNA, plasmids, that consist of only a few genes. prokaryotic ribosomes are slightly smaller than the eukaryotic version and differ in protein and RNA content Populations grow and adapt rapidly produce asexually by binary fission Lack meiotic sex--> mutation is the major source of genetic variation in prokaryotes. Cambrian
Explosion number doubles per generation diversity of animals evolved in the Cambrian period's first 20 million years
most the major phyla of animals evolved. generation times range from 1-3 hours, but some species can double every 20 minutes in an optimal environment Plants, fungi, and animals colonized the land about 500 million years ago
Required adaptations to prevent dehydration
Cuticle on plants Plants colonized land in assosiation with fungi created new opportunites for lifesuch as herbivores and their predators Miller-Urey Experiment Brought up debate of where organic compounds came from R NA was likely to be the first genetic material Prokaryotes can be grouped into four categories according to how they obtain energy and carbon These categories of energy source and carbon source can be combined to group prokaryotes according to four major modes of nutrition. Chemoautotrophs need only CO2 as a carbon source, but they obtain energy by oxidizing inorganic substances, rather than light. The majority of known prokaryotes are chemoheterotrophs. Accessing nitrogen, an essential component of proteins and nucleic acids, is another facet of nutritional diversity among prokaryotes. Eukaryotes are limited in the forms of nitrogen that they can use. In contrast, diverse prokaryotes can metabolize most nitrogenous compounds. During nitrogen fixation, they convert N2 to NH4+, making atmospheric nitrogen available to other organisms for incorporation into organic molecules. Nitrogen fixing cyanobacteria are the most self-sufficient of all organisms. They require only light energy, CO2, N2, water and some minerals to grow. Archea Diversity Based on environmental criteria, archaea can be classified into methanogens, extreme halophiles, and extreme thermophilies. Methanogens are important decomposers in sewage treatment. Methanogens obtain energy by using CO2 to oxidize H2 replacing methane as a waste. • Extreme thermophiles thrive in hot environments
• Extreme halophiles live in such saline places as the Great Salt Lake and the Dead Sea. Technology! The application of organisms to remove pollutants from air, water, and soil is bioremediation. The most familiar example is the use of prokaryote decomposers to treat human sewage. The chemical industry produces acetone, butanol, and other products from bacteria. The pharmaceutical industry cultures bacteria to produce vitamins and antibiotics. The food industry uses bacteria to convert milk to yogurt and various kinds of cheese.
- Protobionts-preceded living cells
- Can store energy, grow, "give birth," undergo osmosis, absorb subsrates, and release the products.
Five-Kingdom System R.H Whittaker 1969 Recognizes two types of cells Prokaryotic in Monera and Eukaryotic in others Seperates multicellular eukaryotes by mode of nutrition Eukaryotes that do not fit into plants, fungi, or animals fall in Protista Three Domain System Any Questions???? The
End!!!! Mitochondria and plastids evolved from endosymbiotic bacteria Bacteria cell walls contain peptidoglycan, a network of modified sugar polymers cross-linked by short polypeptides simpler walls with large amounts of peptidoglycan have less peptidoglycan, more complex, and have an outer membrane containing lipopolysaccharides