Presentation on theme: "Aim: What were the first organisms to appear on Earth?"— Presentation transcript:
1 Aim: What were the first organisms to appear on Earth? HW # 12 read chapter 19Pg.493 q.#40 due thurs
2 Early Earth was hot; atmosphere contained poisonous gases Earth cooled and oceans condensedSimple organic molecules may have formed in the oceansSmall sequences of RNA may have formed and replicatedFirst prokaryotes may have formed when RNA or DNA was enclosed in microspheres
3 Once the organic compounds formed in the oceanic soup of the primitive atmosphere, life was ready to formVirusBacteriaInfluenza virusThese are the simplest form of life that formed first.ProtozoanBacterial cell
4 Prokaryote Cells: (1st Major Kind of Cell) Bacterialack a nucleus and don’t have membrane bound organelles.
5 Virus StructureViruses exist in different shapes, but they are all basically very simple. They are not considered living things.Viruses contain hereditary material and a protein coat. They can duplicate only within living cells.They do not have an energy source to carry out life functions.
6 Millions of years later the prokaryotes became photosynthetic and produced oxygen Gloeocapsa X 400Gloeocapsa is a unicellular cyanobacteria. The gelatinous material surrounding each cell causes the cells to stick togetherRemember, this is happening in water (organic soup).Photosynthetic prokaryotes have extensions of the plasma membrane called thylakoids. Many of the molecules needed in the reactions of photosynthesis are found within the thylakoid membraneTalk in your groups about Why photosynthetic organisms had to evolve at this time?Needed to provide oxygen for a changing atmosphere, as well as supply a food source for developing organismsAnabaena X 400.
7 An oxygenated atmosphere capped by the ozone layer protected the Earth Earth evolved to hold in the oxygen that the photosynthetic prokaryotes were producing.Life as we know it today was now possible
8 Do now: explain how the three changing forces produced the present Earth Geological EvolutionChemical EvolutionBiological Evolution
9 Aim: What did the Eukaryotes contribute to biological evolution? The first eukaryotes may have been communities of prokaryotes.The word means "true nuclei."
10 Eukaryotic cells Characteristics: Nucleus enclosed by a membrane Membrane covered organellesNucleus contains the chromosomes.There are many organelles (small organs) within the cell that carry out specific processes.
11 Approximately 540 million years ago, at the beginning of the Cambrian Period, the fossil record at locations across Earth is marked by the dramatic appearance of complex, diverse, multicellular organisms with hard parts.
12 Ocean Life Diversifies sponges, corals, and brachiopods occupied the seafloor, trilobites, cephalopods
13 In Devonian time, from about 415 to 355 million years ago, fishes of many different types swam and hunted in the seas. Lobe-finned fishes — ancestors to the amphibians — and the early sharks made their appearance by this time.
14 AmphibiansSome lobe-finned fish evolved webbed, leg-like limbs. They probably lived in shallow swampy areas where their limbs allowed them to maneuver more easily than fins. Eventually, they evolved other support systems that prevented them from drying out and allowed them to move on land as the first amphibians. Although amphibians live on land, they must return to water to lay their eggs.
15 …and on landbecause seed-bearing plants do not need water to reproduce, they were able to spread into environments not open to the earliest plants. The casing keeps the seeds from drying out and protects the nutrients, allowing seeds to lie dormant through harsh conditions.
16 Reptiles arose about 300 million years ago, and they replaced amphibians as the dominant land-dwelling animal following the Permian Extinction. Reptiles produce an egg that contains nutrients within a protective shell; unlike amphibians, they do not have to return to the water to reproduce. This difference allowed reptiles to move into new land environments.
17 First DinosaursApproximately 230 million years ago, during the Triassic Period, the dinosaurs appeared, evolved from thereptiles
18 First MammalsFossils of the earliest mammals are more than 200 million years old. These small, shrew-like animals probably lived in caves or burrows and hunted insects and small reptiles at night.
19 Age of MammalsThe Cenozoic Era, from 65 million years ago to today, is the age of mammals and flowering plants and is marked by global cooling. The extinction of the dinosaurs allowed mammals to diversify and grow in size during the Cenozoic.
20 Human AncestorsThe first early hominids may have been bipedal — walking upright on two legs
22 The National Science Foundation’s “Tree of Life” project estimates that there could be anywhere from 5 million to 100 million species on the planet, but science has only identified about 2 millionThough humans have shared the planet with millions of other creatures for thousands of years, we know surprisingly little about our neighbors—we don’t even know exactly how many flora and fauna call Earth home.“We’ve only touched the surface of understanding animal life,” said entomologist Brian Fisher of the California Academy of Sciences. “We’ve discovered just 10 percent of all living things on this planet.”