Unit 1: Biology and Life’s Chemical Basis

1. Unit 1: Biology and Life’s Chemical Basis Chapter 1: The Study of Biology Chapter 2: Life’s Chemical Basis Chapter 3: Molecules of Life

2. Characteristics of Life--CH 1

3. Biology • Biology: the study of life • We also study the origin of life, structures of living things, how living things interact • Biologist: one who studies the diversity of life • Research diseases, develop technology, improve agriculture, preserve the environment

4. Life’s Organization What does it MEAN to be living? To have life? • Defining life is challenging because of the complexities that emerge from the interaction of simple things • Emergent Property: characteristic that results from the arrangement and interaction of parts in a system • A functioning bike emerges only when all the necessary parts connect in the correct way

6. Life’s Unity • Living things share a set of key characteristics → MUST HAVE THEM ALL TO BE LIVING! 1. Homeostasis • Homeostasis: process by which organism keeps its internal conditions within tolerable ranges by sensing and responding to change [INTERNAL REGULATION] • If anything happens within or to an organism that affects homeostasis, processes to restore it begin. • hot → sweat → cold → shiver • Two types of feedback loops -> positive and negative

8. 2. Organization [least complex] atom → molecule → cell → tissue → organ → organ system → multicellular organism → population → community → ecosystem → biosphere [most complex]

9. Life’s Unity 3. Grows & Develops 4. Responds to Environment 5. Adaptations Evolve over Time • Adapt: to become better suited to survive and reproduce in the environment • Evolve: change over time

10. Life’s Unity 6. Cells (Made of one or more) • smallest unit of life! • unicellular: made of only one cell • multicellular: made of many cells 7. Energy (Requires) 8. Reproduces (passed on genetic material) H.O.G.R.A.C.E.R.!!

11. Classification

12. Nature of Science

13. Basic Chemistry, Properties of Water, and Acids/Bases--Ch 2

14. Building Block of Matter • Atoms: building blocks/smallest unit of matter [cells are smallest unit of LIFE] • Atoms typically have same number of protons and electrons • Ion: an atom that has gained/lost electrons in order to achieve a full valence shell, ions carry a charge • gives up electrons = positively charged • gains electrons = negatively charged

15. Building Blocks of Matter • Chemical Bond: attractive force that arises between two atoms when their electrons interact • Ionic bond: electrical attraction between two oppositely charged atoms or groups of atoms • Electronegativity: an atom’s ability to pull electrons away from other atoms

16. Building Blocks of Matter • Covalent Bond: forms when a pair of electrons is shared • Formed between atoms with small/no difference in electronegativity • often stronger than ionic bonds, but not always • Polarity: separation of charge into positive and negative regions caused by UNEQUAL sharing of an electron • Covalent bonds in compounds are usually polar [polar covalent] • If charges are balanced, the molecule is nonpolar

17. Water • Water is important for all living things in some way. • Habitat • Needed for chemical reactions • Dissolving power

18. Water • Water is a polar covalent molecule – Oxygen’s electronegativity is high, making it greedy for electrons • This creates a slight negative charge on the oxygen, and a slight positive charge on the hydrogens • Polarity causes attraction between water molecules, creating hydrogen bonding

19. Water • Hydrogen bond: attraction between the hydrogen atom of one molecule and an atom from a different molecule • In water, positive hydrogens of one molecule attract to negative oxygen of another [opposites attract!!] • Not very strong on their own, but can be very strong if there are many • Hydrogen bonding among water molecules gives rise to unique emergent properties that allow water to sustain life on earth

20. Water 1. Water is a Universal Solvent • Solvent: substance in which another is dissolved • Solute: substance being dissolved • Most chemical reactions important to life happen inside a cell’s watery environment, and water's capacity to dissolve a wide variety of molecules is key to allowing these reactions to take place

21. Water • Water can’t dissolve everything, however • Good at dissolving ions (salt) and polar molecules (sugar) • Substances that dissolve easily in water are hydrophilic [water loving] • Poor at dissolving nonpolar molecules (oils) • Why we need soap!Substances that resist dissolving in water are hydrophobic [water hating]

22. Water 2. Cohesion & Adhesion • Cohesion: attraction of molecules to other molecules of the same kind (caused by hydrogen bonding) • Causes surface tension – tendency of a liquid’s surface to resist rupture when placed under tension or stress [creates water droplets] • Adhesion: force of attraction between unlike molecules (caused by hydrogen bonding) • Causes capillary action – upward “climb” against gravity [water in roots]

23. Water Both Cohesion and Adhesion play a role in many water-based processes in biology, including the movement of water to the tops of trees and the drainage of tears from tear ducts in the corners of your eyes

24. Water 3. Water Stabilizes Temperature • Because of hydrogen bonding, it takes more heat to raise the temperature of water compared with other liquids – it can absorb or release heat without huge change to its own temperature • Water is used by warm-blooded animals [US!] to distribute heat through their bodies, moving heat from warm places to cool places, helping the body keep an even temperature. • HOMEOSTASIS!

25. Water 4. Density of Water • Below 0°C (32°F), water molecules become locked in the bonding pattern of ice • Sheets of ice that form on the surface of ponds, lakes, and streams insulate the water, protecting aquatic organisms during cold winters • When a cell freezes, its watery contents expand and its membrane (like a soda bottle) is broken into pieces.

26. Acids & Bases • When acids or bases are added to water, the molecules dissociate, or break apart, creating hydrogen ions (H+), or hydroxide ions (OH-) • Solutions are classified as acids or bases based on their H+ content when compared to pure water. • Based on the amount of H+ present in a solution, it can affect living organisms.

27. Acids & Bases • Acid: Substance that releases hydrogen ions (H+) when dissolved in water • The more hydrogen released, the more acidic the solution becomes • Base: Substance that releases hydroxide ions (OH-) when dissolved in water • The more hydroxide released, the more basic the solution becomes

28. pH Scale • pH: measure of hydrogen ions in a solution • Acids increase the H+ concentration and bases increase OH- concentration • The pH scale is used to rank solutions in terms of acidity or basicity (alkalinity)

29. pH Scale • Pure water has a pH of 7, making it neutral • Anything below 7 is acidic, and anything above 7 is basic • The closer to 7 a substance is, the weaker it is • Acids and bases are key substances in biology!

30. Acids & Bases • You are a walking, talking bag of water • Most biological molecules can only function properly within a narrow range of pH – HOMEOSTASIS! • Buffers: • mixtures that can react with acids or bases to keep the pH within a particular range. • Work by adding or accepting H+ ions. • Antacids, blood!

31. Acids & Bases • Indicators: substances that change color in the presence of whatever they are testing for • there are many different indicators that can check for many different substances • Acid/base indicators will change color when there is a change in pH

32. Macromolecules---Ch 3

33. CHNOPS • Almost every living thing is made up of 6 elements – carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur • Organic: Molecules that have primarily hydrogen and carbon atoms • Many organic molecules have a backbone that is a chain of carbon atoms • Carbon is the stuff of life – it has a versatile bonding behavior because of its four valence electrons • This means it can easily form chemical bonds with many MANY things!

34. Functional Groups • Combinations of certain elements that give a molecule certain characteristics are called functional groups • Ones to know: • Carboxyl - COOH • Amine - NH3 • Acetyl- COCH3 • Hydroxyl - OH • Methyl - CH3 • Phosphate - PO4

35. Isomers The arrangement of atoms in a molecule can also change chemical properties. Molecules that have the same chemical formula and different structure are called isomers.

36. Organic Molecules • Polymers [also called macromolecules] are large organic molecules made of many of the same repeating subunits, called monomers • Cells build polymers from monomers, and break down polymers to release monomers

37. Building and Breaking of Polymers Both reactions use enzymes (proteins that speed up chemical reactions) • Hydrolysis: Breaks polymers into monomers. (absorbs water) • Dehydration (aka condensation reactions):Joins monomers together to make polymers (releases water)

38. 4 Macromolecules • There are four major types of biological macromolecules in whichALL living things are made from, but the details of each molecule varies by organism

39. Carbohydrates • Organic compound made of carbon, hydrogen, and oxygen in a 1:2:1 ratio – ALWAYS • MONOMER • Monosaccharide: (one sugar) simplest type of carbohydrates • FUNCTION • source of energy, some are a source of structure

41. Carbohydrates • Disaccharides: two monosaccharide monomers • Lactose: glucose + galactose • Sucrose: glucose + fructose • Polysaccharides: chains of hundreds or thousands of monosaccharide monomers, complex carbohydrates

42. Carbohydrates Example Polymers • Cellulose: Main structural component of plants, Tough and insoluble • Chitin: a type of cellulose, durable, translucent, and flexible, strengthens outer body covering of animals [insects, spiders, lobsters] • Starch: Main energy reserve in plants [bread, potatoes, beans, rice] • Glycogen: Main energy reserve in animals, very abundant in muscle and liver cells

43. Lipids • Fatty, oily, or waxy organic compounds made up of C,H,O in the ratio of 1:2: very few • Fatty acid – organic molecules with long [hydrophobic/fatty] “tail” and [hydrophilic/acidic] “head” • MONOMER • fatty acids, glycerol • FUNCTION • store energy, some are used as insulation • EXAMPLES POLYMERS • fats, waxes, steroids, cholesterol

44. Lipids • Fats: lipid that consists of a glycerol molecule with one, two, or three fatty acid tails • Triglyceride: a fat with three fatty acid tails • Saturated Fats: triglycerides with saturated fatty acid tails; tails are flexible and wiggle, solid at room temperature • Unsaturated Fats: triglycerides with unsaturated fatty acid tails; liquid at room temperature

46. Lipids • Trans fats have unsaturated fatty acid tails with hydrogen atoms around the double bonds • Small amounts occur naturally, but most are artificial – partially hydrogenated vegetable oil • Hydrogenation: adds hydrogen atoms to oils in order to change them into solid fats • Trans fats raise the level of cholesterol in our blood more than any other fat and directly alters the function of arteries and veins • Eating as little as 2 grams a day increases the risk of atherosclerosis, heart attack, and diabetes

47. Lipids • Steroids: lipids with no tails • Examples: estrogen and testosterone • Dictates many sex characteristics • Wax: complex, varying mixture of lipids with long fatty acid tails bonded to alcohols or carbon rings • Plants secrete waxes to restrict water loss and keep out parasites and other pests, other types of waxes protect, lubricate, and soften skin and hair

48. Proteins • Structural component of biological organisms – we CANNOT live without proteins. Elements have no ratio. (C, H, O, N, P, sometimes S) • MONOMER • Amino acids [there are 20 different amino acids that make 1,000’s of different combinations] • FUNCTION • movement, defense, cell communication • EXAMPLE POLYMERS • enzymes, hair, muscle, antibodies, some hormones

49. Proteins • We have MANY, MANY different proteins [one cell could have 1,000’s], and they each have a different job • A protein consists of a chain of amino acids and the sequence is determined by the organism’s DNA, one small change could create a different protein! • Due to hydrogen bonding, the chain folds in a repeating pattern creating a 3D protein structure

50. Protein Structures • The four levels of protein structure are distinguished from one another by the degree of complexity in the polypeptide chain. • A single protein molecule may contain one or more of the protein structure types.