Slide 1 / 248 Slide 2 / 248 New Jersey Center for Teaching and Learning AP BIOLOGY Progressive Science Initiative Origins and Molecules This material is made freely available at www.njctl.org of Life and is intended for the non-commercial use of students and teachers. These materials may not be used for any commercial purpose without the written permission of the owners. NJCTL maintains its website for the convenience of teachers who wish to make their work available to other teachers, participate in a virtual professional learning September 2011 community, and/or provide access to course materials to parents, students and others. www.njctl.org Click to go to website: www.njctl.org Slide 3 / 248 Slide 4 / 248 Origins and Molecules of Life Unit Topics Early Universe, LUCA · Early Universe, LUCA Click on the topic to go to that section · Article Discussion Day · Properties of Water · Polymers, Proteins · Carbohydrates, DNA / RNA, Lipids · Water, Carbon, Nitrogen, Phosphorus Cycles · Membranes, Diffusion, Osmosis · Facilitated Diffusion, Sodium Potassium Pump · Electrochemical Gradients · Enzymes, Non-Competitive Inhibition Return to Table of · Optimal Environments Contents · Article Discussion Day Slide 5 / 248 Slide 6 / 248 The Early Universe The Early Universe - Amazing Atoms Earth formed about 10 billion years after the start of the No new elements have been created since Earth formed. universe, about 4.6 billion years ago. This means that all the atoms in you and your world, other than In those 10 billion years, generations of stars were hydrogen and helium, were once inside a star, long ago. born, and died. When Earth, and its solar system, formed, it was in a cloud of matter which included all the naturally occurring elements in the periodic table.
Slide 7 / 248 Slide 8 / 248 Early Earth Early Earth Studies of volcanos suggest the early atmosphere of Earth was composed of a mix of chemical compounds. As Earth's crust cooled and solidified, water vapor condensed to create oceans. The most prevelant were: The atmosphere was likely dominated by hot hydrogen gas, but that gas escaped quickly. Earth was also subject to intense lightning and water vapor (H 2 O) ultraviolet radiation. carbon dioxide (CO 2 ) Up until 3.9 BYA, the environment on Earth was too hostile for life. nitrogen (N 2 ) The earliest fossil evidence for life dates to 3.5 BYA. hydrogen sulfide (H 2 S) methane (CH 4 ) ammonia (NH 3 ) Slide 9 / 248 Slide 10 / 248 The Blue Planet 1 Scientists hypothesize that Earth's early atmosphere contained substances such as: A oxygen, carbon dioxide and hydrogen gas B nitrogen,oxygen, and water vapor Three-quarters of Earth’s surface is submerged in water vapor, methane, and oxygen C water. D ammonia, water vapor, and hydrogen gas The abundance of water is the main reason the Earth is habitable. image courtesy NASA Slide 11 / 248 Slide 12 / 248 Water Molecules Water Molecules Since a water molecule has a positive end and a negative end A water molecule consists of two hydrogen atoms it is called a polar molecule. covalently bonded to one oxygen atom. This property of water causes it to act like a magnet, attracting The more electronegative oxygen atom pulls the electrons other molecules that have positive and negative poles. from the hydrogen atoms toward it, resulting in an uneven distribution of charge. Slight Negative Charge Slight Positive Charge
Slide 13 / 248 Slide 14 / 248 Liquid Water 2 In a water molecule hydrogen and oxygen are bonded together by The polarity of water molecules causes them to be attracted to each other. Ionic bonds A Weak hydrogen bonds form between the hydrogens on one water B Covalent bonds molecule and the oxygen atoms on another to form liquid water. Hydrogen bonds C Van der waals forces D Hydrogen Bonds It was in this chemical medium that life first emerged. Slide 15 / 248 Slide 16 / 248 How life may have emerged 3 Which of the following best describes a hydrogen bond? bond formed through an electrostatic attraction Organic monomers formed and combined to form polymers. A between two oppositely charged ions Phospholipids formed, creating membranes, and created isolated chemical environments. bond formed by the equal sharing of electrons B between two atoms Simple metabolism and self-replication within these environments led to increasingly complex compounds and micromolecules, and the attractive force between neutral molecules C eventually macromolecules. the attractive force between the hydrogen attached The development of RNA marks the transition to life, as metabolism, to an electronegative atom of one molecule and an D self-replication and catalysis became more advanced. electronegative atom of a different molecule Slide 17 / 248 Slide 18 / 248 Organic Monomers Formed Theory 1: Organic Monomers from Space There are two theories for the source of organic monomers The dust in the solar system, from which Earth formed, was rich · Arrival on Earth from space in organic chemicals. · Creation on Earth through chemical reaction Meteorites striking Earth would have hit with lower velocity since the atmosphere was thicker; the monomers would have survived.
Slide 19 / 248 Slide 20 / 248 Organic Monomers from Reactions Theory 2: Organic Monomers from Reactions In 1953, Stanley Miller used Oparin and Two scientists (Oparin and Haldane), in the 1920's, proposed that Haldane's original idea and tested a organic chemistry could have evolved in the early Earth's hypothesis involving an artificial mixture of atmosphere because it contained no oxygen. inorganic molecules while simulating the conditions thought to be found on The oxygen-rich atmosphere of today is corrosive and breaks primitive Earth. molecular bonds. Within days, the experiment produced some of the 20 amino acids presently found in organisms, as well as other organic molecules. Slide 21 / 248 Slide 22 / 248 Stanley Miller's Experiment 4 Miller and other scientists have shown that A simple cells can be produced in a laboratory amino acids and sugars could be produced from inorganic B molecules C cells survived in the primitive atomosphere D life on early earth required material from space Slide 23 / 248 Slide 24 / 248 Dehydration Synthesis 5 Organic compounds are found in which section of Miller's apparatus? A B + OH H From these organic H OH B molecules, polymers C molecule 1 molecule 2 were then formed D A through a process removal of H 2 0 called dehydration water molecule C synthesis D OH H new molecule is formed
Slide 25 / 248 Slide 26 / 248 Hydrolysis 6 Which is true about dehydration synthesis? Part of the process of chemical evolution was that molecules had to one monomer loses a hydrogen atom, the other loses a A react together and then form new molecules. hydroxyl group B electrons are shared between the joined monomers addition of H 2 0 Reacting together water C water is formed when monomers join also involved molecule breaking molecules OH H D covalent bonds are formed between monomers apart. original molecule E all of the above are true This process is OH H OH H and called Hydrolysis . splits into 2 new molecules Slide 27 / 248 Slide 28 / 248 Phospholipids Primitive Cells: Isolated chemical environments Dehydration Synthesis allowed phospholipids to form and naturally created membranes which led to primitive cells, which isolated separate chemical environments. The result is that phospholipids naturally form membrane surfaces that enclose a volume of space. Phospholipids are molecules whose opposite ends are very different: Membranes are an arrangement of phospholipids that gather · One end is polar and can form hydrogen bonds with water together and make a closed shape. Membranes act as a wall or a barrier separating the outside and the inside of the closed shape. · The other end is non-polar and cannot form hydrogen bonds When phospholipids are placed in water, they move so that their hydrophilic ends are in contact with water and their hydrophobic ends are isolated from the water. Slide 29 / 248 Slide 30 / 248 7 The creation of membranes from phospholipids Simple compounds and micromolecules __________________. accumulated and formed macromolecules. A allowed for a more complex chemistry B allowed bacteria to flourish Within the enclosed environment, the processes of chemistry C allowed lipids to make glycoproteins would create even more complex molecules, specifically: D allowed more amino acids to form · Proteins · Carbohydrates · Lipids · Nucleic Acids
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