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Chapter 2 QUICKIE BASIC CHEMISTRY (Review) 1. Structure and function of all living things are governed by the laws of chemistry Understanding the basic.

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Presentation on theme: "Chapter 2 QUICKIE BASIC CHEMISTRY (Review) 1. Structure and function of all living things are governed by the laws of chemistry Understanding the basic."— Presentation transcript:

1 Chapter 2 QUICKIE BASIC CHEMISTRY (Review) 1

2 Structure and function of all living things are governed by the laws of chemistry Understanding the basic principles of chemistry will give you a better understanding of all living things and how they function! “We are all connected; To each other, biologically. To the earth, chemically. To the rest of the universe atomically.” ― Neil deGrasse Tyson QUESTION: What examples can you give of how chemistry is involved in biology?Neil deGrasse Tyson Photosynthesis – Is an example of a chemical reaction

3 CHEMISTRY- The science of the composition, structure, properties, and reactions of matter CHEM REVIEW Matter- Mass- Is MASS the same thing as WEIGHT? – - The pull of gravity on an object is what gives an object its "weight" – - A bowling ball having the same mass on Earth and the moon would weigh less on the moon than it does on Earth due to a gravitational pull present on the Moon. – How much do you weigh on other planets??? Find out here: 3

4 States of Matter SOLID: molecules are tightly linked; little movement and definite shape LIQUID: molecules are less tightly linked; moves more freely than solids; conforms to container GAS: molecules are usually not attracted to one another; move very fast; fills the entire volume of a container 4

5 Elements Pure substances that cannot be broken down into simpler substances Periodic Table created in 1869 by Mendeleev categorizes elements and shows trends 118 elements, 92 occurring naturally 5 Noble or "inert" gases on far right Alkali metals on far left (minus H) Atomic radii increase from left to right and decrease from top to bottom

6 CHONPS Biologists love CHONPS most of all! 96% of all living matter: Sulfur, Phosphorus, Oxygen, Nitrogen, Carbon and Hydrogen (CHONPS). From these six elements, you can make almost any combination of organic molecules! – Carbs – Lipids – Nucleic acids – Amino acids, proteins Living organisms still need 14 other elements, but in smaller amounts. 6

7 Trace elements: Are required by an organism in only minute quantities Make up the remaining 4% of living matter Table 2.1

8 (a) Nitrogen deficiency(b) Iodine deficiency The effects of essential element deficiencies Figure 2.3

9 Atoms Simplest part of an element that retains all properties of that element Too small to see so we make up models to help us understand the structure of atoms and predict how they will act Nucleus- Electrons (-) orbit around nucleus; very fast Farther an E - is from the nucleus- More ENERGY! Atomic Mass- Atomic Number- # of electrons = # of protons - Electrons balance out + charge of protons and have very little mass 9

10 Isotopes Isotopes are atoms that have the same atomic number but a different atomic mass because the number of neutrons differ Examples: 14 C/ 12 C, 127 I, 131 I Radioactive isotopes are useful in dating old objects, imaging body organs and tissues through x-rays and killing cancer cells Radiation can be harmful by damaging cells and DNA and/or causing cancer 2.1 From atoms to molecules larynx thyroid gland trachea b. a. a: © Biomed Commun./Custom Medical Stock Photo; b(patient): Courtesy National Institutes of Health (NIH); b(brain scan): © Mazzlota et al./Photo Researchers, Inc. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10

11 Compounds Most elements do not exist by themselves in nature but rather like to combine with other elements A molecule is formed when two or more atoms join together chemically. A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds. – Chemical properties of compounds are different than the elements alone (2 gases = liquid. Ex: Na + Cl = table salt) “Chemical rxn’s”- chemical bonds can be broken, atoms can be rearranged, and new chemical bonds are formed! 11

12 Bonding Most bonding takes place because atoms are most chemically stable when their outermost energy levels are filled “The Octet Rule” Valence electrons Outer shell electrons are called the valence electrons and are the ones involved in all the bonding and chemical reactions of each atom. Knowing the valence of an electron will give you a better idea of it’s bonding properties To find out how many valence electrons an atom has, you can do a shell diagram (2, 8, 8, 18) or a dot diagram (shows only valence) structure.html 12

13 Bonding Most bonding takes place because atoms are most chemically stable when their outermost energy levels are filled Types of Chemical Bonds Covalent bonds: – Strong bonds – Shared electrons, simulate a full outer orbital 13

14 Polar covalent bond: Electrons are shared, but not evenly shared 14 This creates further potential for hydrogen bonds to form between molecules

15 The Significance of Weak Chemical Bonds Several types of weak chemical bonds are important in living systems Weak chemical bonds – Reinforce the shapes of large molecules – Help molecules adhere to each other – Hydrogen bonds are such bonds

16 Hydrogen Bonds Relatively weak, singly, but rather strong collectively 16

17 Van der Waals Interactions Van der Waals interactions – Occur when transiently positive and negative regions of molecules attract each other

18 Molecular shape – Determines how biological molecules recognize and respond to one another with specificity

19 Molecular Shape often determines function Morphine Carbon Hydrogen Nitrogen Sulfur Oxygen Natural endorphin (a) Structures of endorphin and morphine. The boxed portion of the endorphin molecule (left) binds to receptor molecules on target cells in the brain. The boxed portion of the morphine molecule is a close match. (b) Binding to endorphin receptors. Endorphin receptors on the surface of a brain cell recognize and can bind to both endorphin and morphine. Natural endorphin Endorphin receptors Morphine Brain cell Figure 2.17

20 Ionic Bonds Strong bonds Create ions Create electrical charges: when + and – charges attract, ionic bonds are created OXIDATION: Na becomes (Na + ) = loses e- REDUCTION: Cl becomes (Cl - )= gains an e- 20

21 Energy Basic definition? Laws of Thermodynamics. Energy can neither be created or destroyed but it can be changed from form to form Many energy forms are important in biology: – chemical energy – thermal energy – radiant energy – electrical energy – mechanical energy Amount of energy in the universe remains the same over time – Energy = usable energy + dissipates (ex: heat) Free energy ΔG : energy in a system that is available for work. – For example, in a cell, it is the energy available to fuel cell processes (growth, cell division, metabolism, etc) 21

22 Energy and Chemical Reactions Exergonic rxn’s = release energy (products have less chemical energy than reactants) ex: AB + CD  AC + DB + energy Endergonic rxn’s = absorb energy (products have more chemical energy than reactants) ex: AB + CD + energy  AC + DB Activation energy: energy added to reactants to "jumpstart" the rxn Catalysts: reduce the amount of activation energy that is needed to start the rxn. See Figure 2-7 in your book. 22

23 The energetics of chemical reactions Think about rolling a boulder up a hill…it takes energy input, right? And the boulder at the top of the hill now has that energy stored in it (potential). So the product ends up having MORE energy than the reactant. 23 Think about a boulder rolling down a hill…it has lots of energy. And the boulder at the bottom of the hill now has less (potential) energy. So the product ends up having LESS energy than the reactant.

24 Solutions Water is extremely important to all living things, so the chemistry of living things often involves the study of solutions! Solution: mixture in which substances are uniformly distributed in another substance – Solutions can be mixtures of liquids, solids, or gases Solute: Solvent: Concentration [ ]: measurement of the amount of solute dissolved in a fixed amount of solvent Saturated? Aqueous solutions: 24

25 Acids and Bases Dissociation: force between H 2 O molecules is so strong that the O - atom from one H 2 O molecule can pull off the H + atom from another molecule Water dissociates into H + and OH - equally (hydrogen and hydroxide) A Hydronium ion (H 3 O + )can form when a free H + ion can react with another H 2 O molecule Acidity and Alkalinity is a measure of the relative amount of OH - and H + ions in a solution! Pure water has equal OH - and H + ions in solution; pH of 7.0 Acidic solutions have H + > OH - ions – pH is below 7.0 – sour Basic (alkaline) solutions have H + < OH - ions – pH is above 7.0 – slippery and bitter pH= measure of how many H + ions are in a solution 25 H 2 O H + + OH -

26 Buffers …are chemical substances that neutralize small amounts of either an acid or a base Most chemical rxn’s in living organisms are controlled by pH, therefore... Buffers are very important for maintenance of homeostasis. – If blood pH drops below 7.0 (acidosis), it could be fatal – If blood pH goes above 7.7 (alkalosis), it could be fatal If our blood did not contain a buffering system (bicarbonate ion), we would not be able to drink and eat acidic/basic foods! Great chem review: 26

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