Chapter 2: The Chemical Level of Organization

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Chapter 2 The Chemical Level of Organization
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KEY CONCEPT

• All Matter is made up of atoms
• Atoms join together to form chemicals with
  different characteristics
• Chemical characteristics determine physiology at
  the molecular and cellular level

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Atomic Particles

• Proton
• positive, 1 mass unit
• Neutron
• neutral, 1 mass unit
• Electron
• negative, low mass

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Isotopes

• 2 or more elements with equal numbers of protons
  but different numbers of neutrons

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Elements in the Human Body
Table 21
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Molecules and Compounds

• Molecules
• atoms joined by strong bonds
• Compounds
• atoms joined by strong or weak bonds

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States of Matter

• Solid
• constant volume and shape
• Liquid
• constant volume but change shape
• Gas
• change volume and shape

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Chemical reactions Physiology?

• Energy
• the power to do work
• Work
• a change in mass or distance

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Forms of Energy

• Kinetic energy - energy of motion
• Potential energy - stored energy
• Chemical energy - potential energy stored in
  chemical bonds

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KEY CONCEPT

• When energy is exchanged, heat is produced, but
  cells cannot capture it or use it for work

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Break Down, Build Up

• Decomposition reaction (catabolism)
• AB ??A B
• Synthesis reaction (anabolism)
• A B ??AB
• Exchange reaction (reversible)
• AB ??A B

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KEY CONCEPT

• Reversible reactions seek equilibrium, balancing
  opposing reaction rates
• Add or remove reactants
• reaction rates adjust to reach a new equilibrium

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How do enzymes control metabolism?
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Activation Energy

• Chemical reactions in cells cannot start without
  help
• Activation energy gets a reaction started

Figure 27
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How Enzymes Work
Figure 221
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KEY CONCEPT

• Most chemical reactions that sustain life cannot
  occur unless the right enzymes are present

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Organic and Inorganic Molecules

• Organic
• molecules based on carbon and hydrogen
• Inorganic
• molecules not based on carbon and hydrogen

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Why is water so important to life?
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Properties of Water (1 of 2)

• Solubility
• waters ability to dissolve a solute to make a
  solution
• Reactivity
• most body chemistry uses or occurs in water

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Properties of Water (2 of 2)

• High heat capacity
• waters ability to absorb and retain heat
• Lubrication
• to moisten and reduce friction

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KEY CONCEPT

• Most of our body weight is water
• Water is the key structural and functional
  component of cells and their control mechanisms,
  the nucleic acids

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Electrolytes

• Inorganic ions conduct electricity in solution
• Electrolyte imbalance seriously disturbs vital
  body functions
• Fluid balance
• Blood pressure
• Muscular contractions

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pH

• pH
• the concentration of hydrogen ions (H) in a
  solution
• Neutral pH
• a balance of H and OH
• pure water 7.0

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Acids and Bases

• Acid (acidic) pH lower than 7.0
• high H concentration, low OH concentration
• Base (basic) pH higher than 7.0
• low H concentration, high OH concentration

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pH Scale

• Has an inverse relationship with H
  concentration
• more H ions mean lower pH, less H ions mean
  higher pH

Figure 29
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KEY CONCEPT

• pH of body fluids measures free H ions in
  solution
• Excess H ions (low pH)
• damages cells and tissues, alters proteins
• interferes with normal functions
• Excess OH ions (high pH) also problem
• Normal blood pH 7.35 to 7.45
• Incompatibile with life 6.8 to 7.8

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Acid and Alkaline

• Acidosis
• excess H in body fluid (low pH)
• Loss of bicarbonate
• Blood level lt 7.2
• Alkalosis
• excess OH in body fluid (high pH)
• Blood level gt 7.5

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Nucleic Acids

• Large organic molecules, found in the nucleus,
  which store and process information at the
  molecular level
• DNA and RNA

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Deoxyribonucleic Acid (DNA)

• Deoxyribonucleic Acid (DNA)
• Determines inherited characteristics
• Directs protein synthesis
• Controls enzyme production
• Controls metabolism
• Ribonucleic Acid (RNA)
• Codes intermediate steps in protein synthesis

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KEY CONCEPT

• DNA in the cell nucleus contains the information
  needed to construct all of the proteins in the
  body

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Nucleotides

• Building blocks of DNA
• Have 3 molecular parts
• sugar (deoxyribose)
• phosphate group
• nitrogenous base (A, G, T, C)

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DNA Bases
Figure 222b, c
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Complementary Bases

• Complementary base pairs
• purines pair with pyrimidines
• DNA
• adenine (A) and thymine (T)
• cytosine (C) and guanine (G)
• RNA
• uracil (U) replaces thymine (T)

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Nucleic Acids

• Long chains of nucleotides form RNA and DNA
• RNA and DNA

Figure 223
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RNA and DNA

• RNA
• Single strand
• DNA
• Double helix
• Joined at bases by hydrogen bonds

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Forms of RNA

• Messenger RNA (mRNA)
• Transfer RNA (tRNA)
• Ribosomal RNA (rRNA)

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ADP and ATP

• Adenosine diphosphate (ADP)
• 2 phosphate groups
• di 2
• Adenosine triphosphate (ATP)
• 3 phosphate groups
• tri 3
• Energy for muscular contractions

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KEY CONCEPT

• Body recycles/renews all chemical components at
  intervals ranging from minutes to years
• Metabolic turnover lets your body
• Grow
• Change
• Adapt

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SUMMARY (1 of 2)

• Atoms, molecules, and chemical bonds control
  cellular physiology
• Metabolism and energy work within the cell
• Importance of organic and inorganic nutrients and
  metabolites

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SUMMARY (2 of 2)

• Role of water and solubility in metabolism and
  cell structure
• Chemistry of acids and bases, pH and buffers
• Structure and function of carbohydrates, lipids,
  proteins, and nucleic acids