Week Two: Chapter 17 & 18
Week Two: Chapter 17 & 18 BIO 101
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This 4 page Class Notes was uploaded by Hailey N Detrick on Tuesday September 13, 2016. The Class Notes belongs to BIO 101 at Elon University taught by in Fall 2016. Since its upload, it has received 3 views. For similar materials see Topics in General Biology in Biology at Elon University.
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Date Created: 09/13/16
Week Two: 9/3 – 9/11 Chapter 17 Chapter Questions: 1. What do we know about the history of life on Earth, and how do we know it? a. Earth is at least 4.4 – 4.5 billion years-old b. Earth has gone through many changes c. Everything we know about the earth is due to radiometric dating. 2. What factors helped explain the distribution of species on Earth? a. 250 million years ago, the continents were bound together in a large land mass called Pangaea b. over time the landmass continually split into continents of the northern and southern hemisphere 3. What are the major groups of organisms, and how are organisms placed in groups? a. All organisms are categorized under the phylogenetic tree i. The points on the tree at which the branch splits are called nodes b. Groups: i. Bacteria ii. Archae iii. Eukarya Vocab: 1. Radioactive Isotopes: atoms of elements that are unstable and decay into other atoms 2. Half-life: the time it takes for half the isotopes in a sample to break down 3. Adaptive Radiation: The spreading and diversity of organisms that occur when they colonize a new habitat 4. Mass Extinction: an extinction of between 50% and 90% of all species that occurs relatively rapidly 5. Punctuated Equilibrium: periodic bursts of species change as a result of sudden environmental change 6. Convergent Evolutions: species that aren’t closely related may share similar adaptations as a result of independent episodes of natural selection 7. Taxonomy: the process scientists use to identify, name, and classify organisms 8. Phylogeny: the actual evolutionary history of the organisms Important Note: 1. Urey and Miller Hypothesis: a. Organic molecules can be synthesized by replicating the chemical environment of the early Earth. b. This is important because it showed that given the right conditions, organic molecules could form spontaneously from the inorganic matter. Important Dates: 1. 4.5 billion years-ago: Earth’s predicted age 2. 3.5 billion years-ago: original life on Earth 3. Between 3 – 2.5 billion years-ago: oxygen began accumulating in the atmosphere 4. 450 million years-ago: first organisms on land 5. 250 million years-ago: Permian Extinction Week Two: 9/3 – 9/11 Chapter 18 Chapter questions: 1. What are the prokaryotic domains of life? a. They are unicellular organisms whose single cell lacks a membrane b. ribbon DNA flows freely in the cytoplasm c. No nucleus d. Big in quantity/small in size 2. What are the features of bacteria & archae? a. Archae: has a preference for harsh environments that bacteria can’t inhabit i. “Extremeophiles” because of their ability to live in harsh environments (they can also live in less extreme places) ii. Similar to bacteria iii. Simple cells that lack a nucleus iv. Has a very different genetic code v. No membrane bound organelles b. Bacteria: “invisible work horses” i. Commonly found in microbes ii. Most have a cell wall iii. Some are “autotrophes” (self-eating) iv. Some are “heterotrophes” (other-feeders) 1. Plays an important role in decomposition v. Can be very harmful/disease causing aka “pathogens” 1. Attaching to the host cell wall 2. Or reproducing in the body and interfering with normal processes vi. Comes in different shapes 1. Spherical 2. Rod 3. Spiral vii. Many equipped with flagella: 1. Tiny whip like structures that project from the cell and help it move viii. Has Pili which are shorter and hair like appendages that enable bacteria to adhere to a surface ix. Others are surrounded by a capsule, a sticky outer layer that helps the cell adhere to surfaces and to avoid the defenses of the host 3. What are the challenges faced by organisms living at Lost City, how do they face them? a. There is a distinct lack of oxygen b. It is extremely hot c. There is no sun light for the organisms to photosynthesize Theme: Prokaryotes 1. Prokaryotic Cells: a. Do not have nuclei b. Free range chicken type DNA (no sack to contain the DNA) c. Unicellular organisms d. Very, very small e. No membrane bound organelles i. No chloroplasts ii. No mitochondria f. Living in freezing and harsh environments g. Able to photosynthesize with very limited sun light h. Massive cell wall i. Autotrophs (self-feeding/photosynthesis) j. Hereratrophs (eat other things) 2. Viruses: a. Ultimate parasite b. Are viruses alive or not? i. We have no clue Vocab: 1. Nitrogen Fixation: the conservation of atmospheric nitrogen into a form that plants can use to grow 2. Symbiosis: a relationship in which 2 different organisms live together, often interdependently
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