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What Does Life Require?

What Does Life Require?. Chapter 2 part 1. Objectives. Be able to define life and recognize the necessities of life Be able to describe the properties of water Be familiar with the chemical vocabulary discussed in class Know the basic parts of an Atom and its properties

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What Does Life Require?

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  1. What Does Life Require? Chapter 2 part 1

  2. Objectives • Be able to define life and recognize the necessities of life • Be able to describe the properties of water • Be familiar with the chemical vocabulary discussed in class • Know the basic parts of an Atom and its properties • Understand the relationship between energy level and electron orbit • Be familiar with the kinds of chemical bonds formed between atoms. Understand what causes their formation. • Be familiar with the kinds of chemical bonds formed between molecules. Understand what causes their formation.

  3. Something that experiences: Growth Metabolism-an internal chemistry Reproduction Cells Homeostasis- roughly constant internal environment What is Life?

  4. Water Water is a solvent Water is polar Water is cohesive Water is involved inchemical reactions What does life need?

  5. Solution: a homogenous mixture of two or more substances Solvent: substance that dissolves another Solute: substance that is dissolved Aqueous solution: where water is the solvent Hydrophilic and hydrophobic substances Hydrophilic (water loving): polar or ionic substances Hydrophobic (water fearing): non-polar or non-ionic substances What is a solvent?

  6. Water is a polar molecule. Its polar bonds and asymmetrical “V” shape give water molecules partial units of opposite charge on opposite sides of the molecule. Hydrogen bonding orders water into a higher level of structural organization. The Polarity Of Water Molecules Results In Hydrogen Bonding

  7. ORGANISMS DEPEND ON THE COHESION OF WATER MOLECULES. • Cohesion: Phenomenon of a substance being held together by Hydrogen bonds. • Adhesion: Clinging of one substance to another substance • examples: water transport, capillary action • Surface tension: Measure of how difficult it is to stretch or break the surface of a liquid. • Examples: water strider, overfill

  8. Chemical reactions result from changes in the position of electrons around atoms Usually written as a chemical equation Reactant: materials to be changed Products: new materials that are made during the reaction Sugar + oxygen gas yields Carbon dioxide + Water + energy C6H12O6 + 6O2→6CO2+ 6H2O+ energy Water is involved in Chemical reactions

  9. pH scale ranges from 0 to 14 acidic range is <7 alkaline (basic) range is >7 neutral is =7 Acid: a substance that results in an increase in [H+], generally adds H+ Base: a substance that results in an increase in [OH-] by accepting [H+] pH

  10. Chemistry Basics • Matter: anything that takes up space and has mass • Element: substance that cannot be broken down to other substances by chemical reactions • CHNOPS, Ca, K, Na, Cl, Mg • Trace elements: Fe, I

  11. ATOMS AND MOLECULES • Atom: smallest chemical unit • Atoms usually consist of 3 subatomic particles • Proton • Neutron • Electron • Molecules are made up of two or more atoms connected by a chemical bond

  12. Periodic Table • Atomicnumber • equivalent to the # of Protons • in electrically neutral atoms, also equal to # of electrons • AtomicMass • calculated as sum of protons and neutrons

  13. Energy Levels Of Electrons • Electrons are the only particles involved in chemical reactions • An atom’s electrons vary in their energy level • Energy: ability to do work • Potential energy: amount of energy stored as a result of position or location Potential energy of an atom  as electrons move farther from the atomic center

  14. Electron Numbers Determine Number of Atomic Bonds • Electrons reside in orbitals (3D space) around the atomic core • The number of electrons in the outermost shell of an atom determine its reactivity in chemical reactions

  15. Interaction Between Atoms Make Molecules • Molecule: substance composed of two or more Atoms • Atomic bonds: attractions between atoms as a result of electron interactions • Ionic bonds: result from the transfer of electrons between atoms • Valence shells with 1 or 2 tend to lose; 6 or 7 gain • Covalent bonds: result from the sharing of valence electrons • Polar and nonpolar covalent bonds

  16. Hydrogen Bonds: weak attraction of the positively charged region of one molecule for the negatively charged region of another molecule Chemical Bonds Between Molecules

  17. Nutrients and sources of energy Supplied through the chemicals we eat Four categories of “Macromolecules” Carbohydrates Lipids Proteins Nucleic acids What does life need?

  18. Sugars, the smallest carbohydrates, serve as fuel and carbon sources Monosaccharides Disaccharides: 2 monosaccharides hooked together Type of monosaccharides used differentiate the various disaccharides Carbohydrates: Fuel And Building Material.

  19. CARBOHYDRATES cont. • Polysaccharides: many monosaccharides hooked together • Energy Storage • Glycogen, Starch • Structural Support • Cellulose, Chitin

  20. Proteins: Molecular Tools Of The Cell. • Amino acids: building blocks of Proteins • A Protein is a polymer of amino acids each linked by a peptide bond • Functions: numerous including • Structural, Storage, Transport, Hormonal, Receptor, Contractile, Defensive, Enzymes

  21. STRUCTURE OF AMINO ACID. • Hydrogen atom. • Carboxyl group. • Amino group. • Variable side group.

  22. Amino Acid Diversity • 20 different kinds of side groups enable proteins to be made of many chemically “different” units

  23. Tend to be hydrophobic Lots of Carbon and Hydrogen atoms 3 categories Fats Steroids Phospholipid Lipids

  24. Fats • Fats, Lipids, and Waxes • Store large amounts of energy • Functions of fat • energy storage • insulation • cushioning • Saturated versus unsaturated fats. • Saturated FA chains form no more bonds, Unsaturated FA chains can form more bonds

  25. Steroids • Steriods • Steroid types vary depending on groups attached to ring system • Some Hormones

  26. Phospholipid • Phospholipids • Comprises much of the Plasma Membrane • Both hydrophilic and hydrophobic regions to the molecule

  27. Nucleic Acids • Nucleotide Polymers Convey Information • DNA: information passed down to next generation • Genes • RNA: used when making proteins • messenger RNA • ribosomal RNA • transfer RNA

  28. NUCLEOTIDE STRUCTURE AND FUNCTION. • Phosphate group • Sugar • Ribose • Deoxyribose • Nitrogenous base: • AUGC in RNA • ATGC in DNA

  29. Complimentary Base Pairing is always observed where A is bonded to T and G is bonded to G via Hydrogen bonding

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