The Chemistry of Life

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The Chemistry of Life

• Ch. 6

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• Atoms are the basic building blocks of all
  matter.
• Elements are the 118 fundamental units of matter
  that cant be broken down into simpler
  substances.

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• 96 of the human body is made up of Carbon,
  Hydrogen, Oxygen and Nitrogen.
• Elements are identified by symbols based on their
  name. (ex. Fe for Iron from Ferrum)

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• Certain elements such as Iron and Copper, called
  trace elements, are found in the body in small
  amounts.
• Plants absorb them through their roots and
  animals get them from food.

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• An atom has a nucleus containing protons(p) and
  neutrons(n0) with a cloud of electrons(e-) held
  in place by the attractive force of opposite
  charges.

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• Electrons exist around the nucleus in regions
  known as energy levels which can hold a certain
  number of electrons.
• Ex.
• 1st energy level 2e-
• 2nd energy level 8e-
• 3rd energy level 18e-
• 4th energy level 32e-

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• As atoms get larger they fill these energy levels
  with e- in a certain order, from lowest to
  highest.

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• Atoms contain equal numbers of e- and p and
  therefore have no net charge.
• The properties of elements differ because of the
  fact that they have a different atomic , which
  is the number of protons in the nucleus.

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• While the of p and e- are the same, the of
  n0 may differ.
• Elements may have a variety of isotopes which are
  atoms with differing numbers of n0.
• Ex. Carbon-12 and Carbon-14

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• Many isotopes are radioactive and are unstable.
  They are especially useful in medicine and
  industry.

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• Most elements in nature are found combined with
  other elements to form compounds.
• There are two types of compounds ionic and
  covalent.

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• Ionic compounds are a result of an attraction
  between atoms that occurs when electrons are
  transferred. This creates more stability and a
  net charge or ion is created. Ex. NaCl

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• Covalent compounds are formed when an attraction
  occurs due to the atoms sharing electrons to
  achieve stability.
• Ex. CO2, glucose, H2O.

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• When covalent bonds form they create molecules,
  which are a group of atoms chemically combined
  and having different properties than the
  individual atoms.

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• Ionic bonds form compounds that have different
  properties than the individual atoms as well.
  Most ionic compounds are formed when a metal
  transfers an electron(s) to a nonmetal so that it
  can achieve a more stable electron structure.

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• Chemical equations show how chemicals react to
  form new compounds. An equation must be balanced
  to show that no atoms were lost or gained in the
  chemical reaction. Coefficients are placed in
  front of the compound to adjust the total number
  of atoms.

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• Mixtures are a combination of substances in which
  the individual components retain their own
  properties.
• Ex. Dirt, blood

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• Solutions are mixtures in which one or more
  substances (solutes) are distributed evenly in
  another substance (solvent).
• Ex. saltwater

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• Chemical reactions occur only when conditions are
  right. Reactions may depend on available energy,
  temperature or a certain concentration of a
  substance dissolved in solution.

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• Chemical reactions can also depend on the pH of a
  solution.
• The pH is a measure of how acidic or basic a
  solution is. A scale ranging with values from
  0-14 is used to measure pH.

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• An acid is a substance that forms Hydrogen ions
  (H) in water.
• The pH of an acid is less than 7 and will turn
  blue litmus paper red.

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• A base is a substance that forms Hydroxide ions
  (OH-) in water.
• The pH of a base is more than 7 and turns red
  litmus paper blue.

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• Water, because of its unique properties is the
  most important compound in living organisms.
• Water dissolves substances and allows them to be
  transported to the cell.

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• Water is a polar molecule even though it is
  covalent.
• This is because oxygen has a stronger attraction
  for electrons than does Hydrogen.
• The electrons are pulled closer to Oxygen as a
  result and leave Hydrogen with a partial positive
  charge.

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• All objects in motion possess kinetic energy.
• Particles behave like ping pong balls and
  constantly collide and rebound.
• This can be observed with a microscope and pollen
  grains and is called Brownian motion.

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• Diffusion is the net movement of particles from
  an area of higher concentration to an area of
  lower concentration.
• The rate of diffusion can be affected by
  temperature, pressure and solution concentration.

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• When the movement of molecules continues but
  there is no net change in concentration the
  solution is said to be in dynamic equilibrium

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• Diffusion is one the methods that materials move
  in and out of the cell.
• When materials move from higher to lower
  concentration they are said to move with the
  gradient.
• Oxygen also moves into the capillaries of the
  lungs by diffusion.

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• Carbon has four valence electrons .
• These electrons form four covalent bonds in order
  to become stable.
• It can form single double or triple bonds with
  other carbon atoms and can form a huge number of
  structures.

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• Carbon structures that have the same chemical
  formula but different three dimensional
  structures are called isomers. Ex. Glucose and
  fructose.

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• Carbon can form large biomolecules such as
  proteins.
• Cells build biomolecules by bonding small
  molecules together to form chains called
  polymers.

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• Carbohydrates are biomolecules composed of
  carbon, hydrogen and oxygen with a ratio of about
  two H and one O for every C.
• The simplest type of carbohydrate is called a
  monosaccharide. Ex. Glucose and fructose

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• Simple polymers can be formed by condensation
  reactions where water forms from a H and OH from
  two smaller molecules.
• The opposite occurs with the addition of H2O and
  is called hydrolysis.

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• Two monosaccharide molecules can combine to form
  a disaccharide, which is a two sugar
  carbohydrate.
• Glucose and fructose combine to form sucrose by a
  condensation reaction.

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• The largest carbohydrate molecules are
  polysaccharides.
• These are composed of many monosaccharide
  subunits.
• Ex. Starch, glycogen and cellulose.

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• Starch consists of branched chains of glucose
  units and is used as energy by plant cells and
  food reservoirs in seeds and bulbs.

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• Glycogen is a highly branched polymer stored in
  the liver
• Cellulose is another glucose polymer that forms
  the cell walls of plants and gives plants
  structural support. Its structure looks like a
  chain link fence.

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• Lipids are large biomolecules made mostly of
  carbon and Hydrogen with a small amount of
  Oxygen. They are insoluble, nonpolar and not
  attracted to water molecules (hydrophobic). Ex.
  Fats, oils, wax steroids.

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• A fatty acid is along chain of carbon and
  hydrogen.
• If all the carbons are bonded to other carbons it
  is said to be saturated.
• If a double bond is present it is said to be
  unsaturated.
• Fatty acids with more than one double bond are
  called polyunsaturated.

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• Lipids are very important for the proper
  functioning of organisms.
• Cells use lipids for energy storage, insulation
  and protective coverings.

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• Proteins provide structure for tissues and organs
  and carry out cell metabolism.
• A protein is a large complex polymer composed of
  carbon , hydrogen, oxygen, nitrogen and sometimes
  sulfur.

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• The basic building blocks of proteins are amino
  acids. There are about 20 common amino acids.
• These building blocks, in various combinations,
  make literally thousands of proteins.

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• Amino acids have peptide bonds that is covalent
  and is formed when a water molecule is removed.

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• An enzyme is a protein that changes the rate of a
  chemical reaction.
• Enzymes are involve in almost all metabolic
  processes.

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• A nucleic acid is a complex biomolecule that
  stores celluar information in the form of a code.
• Nucleic acids are polymers made up of smaller
  subunits called nucleotides.

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• Nucleotides are arranged in three groups a
  nitrogenous base, a simple sugar and a phosphate
  group.
• Ex. DNA-deoxyribonucleic acid
• RNA- ribonucleic acid

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• DNA is the master copy of an organisms
  information code.
• The info in DNA contains the instructions used to
  form all of an organisms enzymes and structural
  proteins.

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• RNA is a nucleic acid that forms a copy of DNA
  used in making proteins.