BIOCHEMISTRY

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BIOCHEMISTRY

• (PART TWO)

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Chemical Bonds

• Hydrogen Bonds
• Bonds that hold hydrogen-containing molecules
  together
• This is why water forms beads
• Occurs between moleculesoutside of compounds

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Water (H2O)

• Most abundant compound in organisms
• Water is polar
• Has an unequal distribution of electrons between
  hydrogen oxygen atoms
• The oxygen is slightly more negative because the
  electrons are attracted more to it than hydrogen
• The hydrogen is slightly more positive because
  they are missing the electrons that are more
  attracted to oxygen
• What kind of bond is present in H20?
• Makes it possible for other compounds to dissolve
  in water
• Water has a positive side and a negative side
• Which side is positive?
• Which side is negative?

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Water (H2O)

• Water has hydrogen bonds
• Water is cohesive (because of polarity)
• Cohesion attraction between molecules of the
  same element
• Ex. H2O molecules sticking to H2O molecules
• This is what allows some insects spiders to
  walk on the surface

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Water (H2O)

• Water is adhesive
• Adhesion attraction between molecules of
  different elements
• Ex. H2O sticking to other substances
• water sticking to the sides of a graduated
  cylinder
• This is what causes water to bend at the surface
• Causes capillary action pulls a column of water
  to the top of a plant

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Water (H2O)

• Water exhibits evaporative cooling
• It removes heat when it evaporates from a surface
• Ex. Sweating cools skin
• Water expands during freezing
• It expands into crystal formation, releasing
  heatcauses ice to be less dense than liquid
  water
• Ex. Rocks are broken up by ice, creating soil
• Ex. Ice layer protects fruit from freezing

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Solutions and Suspensions

• Mixture
• A material composed of two or more elements or
  compounds that are physically mixed together but
  not chemically combined
• They can be physically seperated
• Ex Salt and pepper mixture
• Two types of mixtures that can be made with water
• Solutions
• Suspensions

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Solutions

• Solution
• A mixture in which all of the components are
  evenly distributed throughout the solution
• Solution solvent solute
• Solute
• The substance that is dissolved
• Solvent
• The substance in which the solute dissolves
• Water is the universal solvent OR the greatest
  solvent on earth
• Examples Kool-aid or Soda
• Is a homogeneous mixture

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Suspensions

• Suspension
• A mixture in which some materials do not dissolve
  when placed in water but separate into pieces and
  are suspended in the water
• Suspension water non-dissolved material
• Example Italian Salad Dressing

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pH scale

• The pH scale measures the concentration of H
  ions
• The pH of substances ranges from 0-14
• 0-6.9 acid
• 7 neutral
• 7.1-14 base
• The lower the number the more ________?
• The higher the number the more ________?

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Buffers

• Buffers
• Weak acids or weak bases that react with strong
  acids or strong bases to prevent sharp, sudden
  changes in pH
• Help to neutralize so that the body can maintain
  homeostasis
• Help to control pH in blood digestive tract
• pH of most fluids in the body 6.5-7.5

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Acids Bases

• Acid
• Forms H ions in solutions
• Acidic solutions have higher concentrations of H
  ions than water
• Base
• Forms hydroxide ions (OH-) in solutions
• Basic solutions have lower concentrations of H
  ions than water

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Review Questions

• What are buffers?
• What is the pH of the strongest base?
• What is a suspension?
• What is the makeup of a molecule of water?
• What is the pH of the strongest acid?
• What is the most abundant compound in most living
  things?
• What is the pH of the weakest acid?
• What is a mixture?

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Review Questions

• What is the pH of the weakest base?
• What is a solution?
• What is the pH range of acids?
• When salt is dissolved in water, water is the
  _________.
• Why are water molecules polar?
• What is the pH range of bases?
• In a pitcher of Kool-Aid, the Kool-Aid powder is
  the ________.

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Review Questions

• Give an example of a solution.
• What does the pH scale measure?
• What is cohesion?
• Give an example of a suspension.
• What is adhesion?