Cells and Cell Chemistry

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Cells and Cell Chemistry

• Level of Chemical Organization of the Body
• Matter is anything that occupies space and has
  mass
• In the body, most chemicals are in the form of
  molecules. Molecules are particles of matter
  that are composed of atoms.
• Elements are pure substances.
• Compounds are substances whose molecules have
  more than one element.
• Atoms the smallest particle of an element that
  has the chemical properties of the substance
• Are composed of protons, electrons, and neutrons

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• The core of the atom is the nucleus.
• It consists of
• Protons (positive) charge, have mass number
  of protons in the nucleus is the atoms atomic
  number.
• Neutrons have no charge (neutral particle) The
  number of protons and neutrons combined is the
  atomic mass of an atom.
• Electrons - (negative) charge, surround the
  nucleus in a circle which is called an orbital.
  Have no measurable mass.
• Orbitals are arranged into energy levels

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• The first energy level of an atom can hold 2
  electrons
• The second level can hold up to 8 electrons
• Electrons have potential energy
• Each orbital further away from the nucleus has a
  higher level of energy
• -- When an electron moves to an orbital closer to
  the nucleus it loses energy
• --When an electron moves to an orbital further
  away from the nucleus, it gains energy
• In an electrically neutral atom, there is one
  electron for every proton.

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• Atoms are chemically stable when the outer
  occupied energy level is completely filled
• Atoms react with one another in ways to make
  their outermost energy level full. To do this,
  atoms can share, donate, or borrow electrons.
• The first shell can hold 2 electrons the second
  can hold 8 electrons few atoms have a third
  shell
• These interactions cause the atoms to bind to
  each other this is called a chemical bond
• Types of chemical bonds
• Covalent
• Ionic

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• Covalent Bond
• Formed by the sharing of electrons with another
  atom (in order to fill the outermost shell)
• Sharing of 1 pair of electrons (one electron from
  each atom) is a single bond
• Sharing of 2 pairs of electrons is a double bond
• Because atoms involved in a covalent bond must
  stay close to each other, covalent bonds are
  strong and normally dont dissociate (break
  apart) in water.
• Example Hydrogen gas

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• Ionic bond- bond which is formed between an atom
  that has 1-2 electrons in its outer energy shell
  and an atom that needs only 1-2 electrons to fill
  its outer level.
• The atom with 1-2 electrons transfers its outer
  shell electron(s) to the other atom.
• charge for each electron lost
• - charge for each electron gained
• An electrically charged atom or molecule is
  called an ion. Examples Na, Cl-
• The bond is of moderate strength and dissolves
  easily in water (called dissociating).
• Molecules that form ions when dissolved in water
  are called electrolytes.

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Compounds

• Compounds are substances whose molecules have
  more than one element.
• Organic compounds are composed of molecules that
  contain carbon
• Inorganic compounds do not contain carbon

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• Life depends on water.
• Water is essential to life.
• It is the most abundant compound in the body
• Water is a solvent (liquid into which solutes are
  dissolved)and forms aqueous solutions in the body
• Water is involved in chemical reactions within
  the body.
• Chemical reactions are interactions among
  molecules in which atoms group into new
  combinations.

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• Acids, bases, and salts
• Are compounds that affect chemical reactions in
  the body
• Water molecules dissociate to form equal amounts
  of H (hydrogen ions) and OH (hydroxide ions)
• Acidsubstance that shifts the H/OH balance in
  favor of H opposite of base
• Basesubstance that shifts the H/OH balance
  against H also known as an alkaline substance
  opposite of acid
• pHexpression of H concentration in a solution
• 7 is neutral
• pH values above 7 are basic pH values below 7
  are acidic

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• Neutralization occurs when acids and bases mix
  together
• Buffers are chemical systems that absorb excess
  acids or bases and thus maintain a relatively
  stable pH

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Basic Structure and Function of each major
organic compound in the body

• Carbohydrates
• Lipids (fats)
• Proteins
• Nucleic acids

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• Carbohydratessugars and complex carbohydrates
• Contain carbon (C), hydrogen (H), oxygen (O)
• Made up of carbon subunits called
• Monosaccharides or single sugars (e.g., glucose)
• Disaccharidedouble sugar made up of two
  monosaccharide units (e.g., sucrose, lactose)
• --Polysaccharidecomplex carbohydrate made up of
  many monosaccharide units (e.g., glycogen made up
  of many glucose units)
• Function of carbohydrates is to store energy for
  later use
• --liver and muscle cells form glycogen when there
  is an excess of glucose in the blood.

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• Lipidsfats and oils
• Trigylcerides
• Made up of one glycerol unit and three fatty
  acids
• Store energy for use later
• Phospholipids
• ---Similar to triglyceride structure, except
  with only two fatty acids, and with a
  phosphorus-containing group attached to glycerol
• ---The head attracts water and the double
  tail does not, thus forming stable double
  layers (bilayers) in water
• ---Phospholipids form cell membranes

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• Cholesterol a steroid lipid
• Molecules have a steroid structure made up of
  multiple rings
• Cholesterol stabilizes the phospholipid tails in
  cell membranes and is converted into steroid
  hormones (estrogen, testosterone, cortisone) by
  the body

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• Proteins
• Very large molecules made up of amino acids held
  together in long folded chains by peptide bonds
• Structural proteins
• Form structures of the body
• Collagen is a fibrous protein that holds many
  tissues together
• Keratin forms tough waterproof fibers in the
  outer layer of the skin

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• Functional proteins
• Participate in the bodys chemical processes
• Examples hormones, cell membrane channels and
  receptors, enzymes
• Enzymes
• Are Catalystshelp chemical reactions occur but
  remain unchanged
• Lock-and-keyeach enzyme fits a particular
  molecule that it acts on as a key fits into a
  lock
• Proteins can combine with other organic molecules
  to form glycoproteins or lipoproteins

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• Nucleic acids-DNA (deoxyribonucleic acid) and RNA
  (ribonucleic acid)
• Made up of nucleotide units, each consisting of
• Sugar (ribose or deoxyribose)
• Phosphate
• Nitrogen bases adenine, thymine or uracil,
  guanine, cytosine
• Nucleotides bind to one another to form strands
  or similar structures
• DNA (deoxyribonucleic acid)-double helix
• Used as the cells master code for assembling
  proteins
• Uses deoxyribose as the sugar and Adenine,
  Thymine and Guanine and Cytosine (no uracil)
• Forms a double helix

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• RNA (ribonucleic acid)
• Used as a temporary working copy of a gene
  (portion of the DNA code)
• Uses ribose as the sugar and Adenine, Uracil,
  Cytosine, and Guanine as bases (no thymine)
• By directing the formation of structural and
  functional proteins, nucleic acids ultimately
  direct structure and function of the entire body