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Cells and Cell Chemistry

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Title: Cells and Cell Chemistry


1
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

2
  • 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

3
  • 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.

4
  • 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

5
  • 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

6
  • 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.

7
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

8
  • 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.

9
  • 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

10
  • 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

11
Basic Structure and Function of each major
organic compound in the body
  • Carbohydrates
  • Lipids (fats)
  • Proteins
  • Nucleic acids

12
  • 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.

13
  • 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

14
  • 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

15
  • 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

16
  • 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

17
  • 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

18
  • 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
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