Chemistry Review

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Chemistry Review

• Competency 2

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The Chemistry of Life

• Life is composed of MATTER (anything that
  occupies space and has mass)
• Matter is composed of chemical ELEMENTS
  (substances that cannot be broken down into other
  substances)
• About 92 elements that occur in nature
• COMPOUNDS - substances containing two or more
  elements (ex. chlorophyll)
• ATOMS - smallest unit of matter that still
  retains the properties of an element, each
  element consists of one type of atom

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Structure of the Atom

• Nucleus of the atom contains protons (positive)
  and neutrons (neutral) and the shell of the atom
  contains electrons

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• All atoms of a particular element have the same
  number of protons - this the elements ATOMIC
  NUMBER
• MASS NUMBER or ATOMIC WEIGHT- refers to the sum
  of the protons and neutrons in the nucleus.
• ISOTOPES - variant forms of an element, these
  forms differ in the number of neutrons they
  contain

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Elements in Living Thing

• Oxygen - O
• Carbon - C
• Hydrogen - H
• Nitrogen - N

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CHEMICAL BONDS

• IONIC BONDS - an electron is "donated"
  (transferred) to another atom

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CHEMICAL BONDS

• COVALENT BONDS - electrons are shared between
  atoms

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CHEMICAL BONDS

• HYDROGEN BOND weak chemical bond found in water
  and DNA

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WATER

• Water's properties make it unique and essential
  for life processes (and all life on earth)
• 1. Water is formed by polar covalent bonds,
  which determine the arrangement of water
  molecules. (Universal solvent)
• 2. HYDROGEN BONDS - weak bonds that form
  betweeen molecules, the positive hydrogen atom is
  attracted to the negatively charged atom on
  another water, which creates COHESION.
• 3. COHESION results in SURFACE TENSION, this
  property of water is what allows insects and
  other small animals to walk across water.

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Water Molecule
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Organic Compounds

• Compounds synthesized by cells and contain carbon

Reaction Types Hydrolysis - break down compounds
by adding water Dehydration - two components
brought together, produces H2O Endergonic -
requires the input of energy Exergonic -
releases energy
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4 Organic Compounds of Life

• 1. Carbohydrates2. Lipids3. Proteins4.
  Nucleic Acids

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1. CARBOHYDRATES

• monosaccharides - simple ring sugars, glucose and
  fructose
• disaccharides - two monosaccharides combined,
  sucrose and lactose
• polysaccharides - polymers of monosaccharides,
  starch and glycogen

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2. Lipids

• Hydrophobic
• waxes, oils, fats, steroids (cholesterol sex
  hormones)
• important structural component of the cell
  membrane (phospholipid)
• Saturated fats contain no double bonds

Saturated fats solidy at room temperature,
unsaturated fats are liquid at room temperature
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3. Proteins

• Polymers made of amino acids
• Amino acids are joined by peptide bonds in
  ribosomes
• Amino acids form a wide variety of structures,
  building blocks for living tissue

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Amino Acids

• Building blocks of proteins / polypeptides

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4. Nucleic Acids

• Informational polymers
• DNA RNA
• Made from nucleotides

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Nucleotidesbuilding blocks of nucleic acids

• 3 parts
• 1. 5 carbon sugar
• 2. phosphate
• 3. nitrogen base

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How Enzymes Work

• Enzymes are biological catalysts that changes the
  speed of chemical reactions without themselves
  being changed at the end of the reaction.
• Properties of Enzymes
• Enzymes are made of proteins.
• They speed up chemical reactions inside the
  cytoplasm.
• They are needed only in small amounts
• They remain unchanged after each reaction and can
  therefore be reused.

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Lock and Key Model of How Enzymes Work

• As an enzyme works it combines with its substrate
  and converts it to product(s).
• Substrate is a molecule upon which an enzyme acts
  

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pH Scale

• pH scale determines how acidic or basic a
  substance is.
• Ranges from 0-14
• pH of 7 is neutral
• pH less than 7 is acidic
• pH greater than 7 is basic