The Chemical Composition of Cells

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The Chemical Composition of Cells

• Chapter 2

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Learning Objectives- 1

• Understand the Structure of the Molecular
  Components of Living Organisms
• Carbohydrates, which supply and store energy and
  serve as structural building blocks, include
  sugars and polymers of sugars.
• Proteins, which catalyze reactions and are
  structural building blocks, are polymers of amino
  acids.
• The nucleic acids DNA and RNA, which code and
  express genetic information, are polymers of
  nucleotides.
• Lipids are membrane components consisting mainly
  of carbon and hydrogen atoms derived from
  acetates and other molecules.
• Secondary metabolites such as phenolics,
  alkaloids, and terpenoids often protect or
  strengthen plants.

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Learning Objectives -2

• To Understand Energy and Chemical Reactions
• Energy can be stored and can move or change
  matter .
• Chemical reactions involve either a net input or
  a net output of free energy.
• The movement of electrons is the basis of energy
  transfer through oxidation and reduction
  reactions.
• The terminal phosphate bond in ATP releases
  energy when broken.
• NADH, NADPH, and FADH2 are universal carriers of
  energy-rich electrons in living organisms.

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Learning Objectives -3

• To Understand the Nature of Chemical Reactions
  and Enzymes
• Enzymes position reactants, allowing reactions to
  occur with minimal activation energy or increase
  in temperature.
• Cofactors such as coenzymes interact with enzymes
  to assist reactions and indirectly provide energy
  in the form of electrons for biochemical
  reactions.
• Competitive and noncompetitive inhibition can
  slow or stop enzymatic reactions and pathways.
• Enzymatic reactions are linked together into
  metabolic pathways.

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Learning Objective

• Know the basic structure of atom, and know the
  role of ionic, covalent and hydrogen bonds.

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Key Terms Atoms

• Proton
• positive electric charge, small mass
• Neutron
• uncharged, about same mass as proton
• Electron
• negative charge, extremely small mass

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A Carbon Atom
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Electrons

• Move around the nucleus at different energy
  levels
• Allow elements to combine chemically to form
  chemical compounds
• Ions are atoms which tend to gain or lose
  electrons

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Electron Configurations
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Acids and Bases

• Acids dissociate in water to form hydrogen ions
  (protons, H)
• Bases dissociate in water to yield negatively
  charged hydroxide ions (OH-)

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pH Scale

• A measure of the relative concentrations of H
  and OH- in a solution
• A solutions acidity or alkalinity is expressed
  in terms of the pH scale

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KEY TERMS

• IONIC BOND
• An electrostatic attraction between oppositely
  charged ions

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Ionic Bonding
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KEY TERMS

• COVALENT BOND
• A chemical bond involving one or more shared
  pairs of electrons

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Covalent Bonding in Hydrogen
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Covalent Bonding in Methane
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KEY TERMS

• HYDROGEN BOND
• An attraction between a slightly positive
  hydrogen atom in one molecule and a slightly
  negative atom (usually oxygen) in another
  molecule

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Animation How Atoms Bond
CLICKTO PLAY
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LEARNING OBJECTIVE

• Discuss the properties of water, and explain the
  importance of water to life

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Water

• Has a strong dissolving ability
• Molecules form hydrogen bonds with one another
  (cohesion)
• Molecules form hydrogen bonds to substances with
  ionic or polar regions (adhesion)
• Adhesion Cohesion are particularly important
  for transport
• All living things require water to survive
• Almost all chemical reactions that sustain life
  occur in aqueous solution
• High Melting Freezing Points
• Insulation Property after freezing (e.g., lakes)

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Water Structure
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Animation Structure of Water
CLICKTO PLAY
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LEARNING OBJECTIVE

• Describe the chemical compositions and functions
  of carbohydrates, lipids, proteins, and nucleic
  acids

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KEY TERMS

• CARBOHYDRATE
• An organic compound containing carbon, hydrogen,
  and oxygen in the approximate ratio of 1C2H1O

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Carbohydrates 1

• Include sugars, starches, cellulose
• Important fuel molecules, components of molecules
  (nucleic acids) and cell walls

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Carbohydrates 2

• Monosaccharides
• simple sugars
• Disaccharides
• two monosaccharide units
• Polysaccharides
• many monosaccharide units

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Common Monosaccharides
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Sucrose Synthesis
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Starch A Storage Polysaccharide
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Cellulose A Structural Polysaccharide
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KEY TERMS

• LIPID
• Any of a group of organic compounds that are
  insoluble in water but soluble in fat solvents

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Lipids 1

• Have a greasy consistency, do not readily
  dissolve in water
• Important fuel molecules, components of cell
  membranes, waterproof coverings over plant
  surfaces, light-gathering molecules for
  photosynthesis

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Lipids 2

• A neutral fat or oil molecule is composed of a
  molecule of glycerol plus one, two or three fatty
  acids

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Formation of a Neutral Fat or Oil
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KEY TERMS

• PROTEIN
• A large, complex organic compound composed of
  amino acid subunits

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Protein

• A macromolecule composed of amino acids joined by
  peptide bonds
• Order of amino acids determines structure and
  function of a protein molecule
• Enzymes Proteins that increase the rate of
  chemical reactions

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Amino Acids
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Peptide Bonds
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Protein Synthesis Animation

• http//www.wisc-online.com/objects/index_tj.asp?ob
  jidAP1302

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Organization of Protein Molecules
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KEY TERMS

• NUCLEIC ACID
• Deoxyribonucleic acid (DNA) and ribonucleic acid
  (RNA)
• Large, complex organic molecules composed of
  nucleotides

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Nucleic Acids

• Control the cells life processes
• Deoxyribonucleic acid (DNA)
• Transmits information from one generation to the
  next
• Ribonucleic acid (RNA)
• Involved in protein synthesis

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Nucleotides

• Repeating units that form nucleic acids
• Order of nucleotides in a nucleic acid chain
  determines the specific information encoded
• Adenosine triphosphate (ATP)
• A modified nucleotide compound important in
  energy transfers in biological systems

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Nucleic Acids
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Nucleic Acids
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Nucleic Acids
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DNA Replication Animation

• http//www.visionlearning.com/library/module_viewe
  r.php?mid63lc3

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KEY TERMS

• ADENOSINE TRIPHOSPHATE (ATP)
• An organic compound of prime importance for
  energy transfers in biological systems

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ATP

• ATP is a nucleotide that performs many essential
  roles in the cell.
• It is the major energy currency of the cell,
  providing the energy for most of the
  energy-consuming activities of the cell.
• It is one of the monomers used in the synthesis
  of RNA and, after conversion to deoxyATP (dATP),
  DNA.
• It regulates many biochemical pathways.

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LEARNING OBJECTIVE

• Discuss the role of enzymes in cells

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KEY TERMS

• ENZYME
• An organic catalyst, produced within an organism,
  that accelerates specific chemical reactions
• ACTIVATION ENERGY
• The energy required to initiate a chemical
  reaction

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Enzymes

• Speed up a chemical reaction by lowering its
  activation energy (energy needed to initiate the
  reaction)
• Most enzymes are highly specific and catalyze
  only a single chemical reaction
• Without enzymes, chemical reactions in cells
  would occur too slowly to support life

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Enzymes and Activation Energy
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Enzyme-Substrate Complex
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Energy Chemical Reactions

• Energy can be stored and can move or change
  matter Potential energy is stored energy, while
  kinetic energy is energy having to do with
  motion.
• The first law of thermodynamics states energy can
  be harnessed and transformed but not created or
  destroyed.
• The second law of thermodynamics states that
  every transfer of energy increases the entropy
  (disorder) of matter in the universe.

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LEARNING OBJECTIVE

• State the first and second laws of
  thermodynamics, and describe how each applies to
  plants and other organisms

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KEY TERMS

• FIRST LAW OF THERMODYNAMICS
• Energy cannot be created or destroyed, although
  it can be transformed from one form to another
• SECOND LAW OF THERMODYNAMICS
• When energy is converted from one form to
  another, some of it is degraded into a
  lower-quality, less useful form

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Energy

• The ability to do work
• Plants and other organisms cannot create the
  energy they require to live, but must capture
  energy from the environment and use it to do
  biological work

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Potential and Kinetic Energy
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Entropy

• Continuously increases in the universe as usable
  energy is converted to lower-quality, less usable
  form (heat)
• As each energy transformation occurs in
  organisms, some energy changes to heat
• Given off into the surroundings
• Can never be used again for biological work

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Animation Activation Energy
Click To Start
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Secondary Metabolites

• Secondary metabolites such as phenolics,
  alkaloids, and terpenoids often protect or
  strengthen plants