Lecture 2 Chemistry of Life by ild18893

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									Lecture 2: Chemistry of Life and Cell Intro
BSCI 124
Spring 2002

All matter in the universe is made up of elements (92 natural!)
       99.5% = Life H, O, N, C, K, Mg, Ca, P, S (others are trace elements or micronutrients)

atom – smallest part of an element that still retains the chemical and physical characteristics of
that element
        subatomic particles : protons (+)
                              neutrons (neutral)
                              electrons (-)
        protons and neutrons make up the atomic nucleus while the electrons orbit the atomic
nucleus
               atomic number - number of protons in an atomic nucleus (constant)
               mass number – number of protons and neutrons in the atomic neuclus, may vary
                              how to get isotopes

Molecules – when atoms are combined ie. Water

Compound – 2 or more elements in a definate proportion ie. Sugars

Chemical bonds – forces that hold atoms together
      1. ionic – two oppositely charged ions come together, strong ie. NaCl
                     ion – atom with charge
                     valence – number of electrons added or lost
      2. covalent – two atoms share electron pairs, stonger, biologically important ie. O2
                     nonpolar vs polar
      3. hydrogen – partial positive and partial negative of water attract, weak alone but
          strong/stable in numbers.

Macromolecules – large complex

1. carbohydrates – sugars and starches, cellulose
              monosaccharides –fructose disaccharide—sucrose, maltose polysaccharide
2. Proteins – long chains of amino acids called polypeptide chains
                     Folded to a 3-D structure
                     Ie. Enzymes, regulating molecutes, transport, structure
3. Lipid – only C and H  oils, and fats
              Triglycerides (E), phospholipid (membranes), waxes (membranes), and steroids
              (hormones)
4. Nucleic Acids – C, H, O, N, P , made up of nucleotides—sugar + phosphate + nitrogenous
   base (purines: A, G pyrimidines: T,C, U) ie. DNA, RNA
Cells

1665 Robert Hooke – cork w/ primative microscope, organized into units that resemble the
cubicles in monasteries = ―cells‖

        cell – basic unit of life

mid-19th century – Schleiden, Schwann, Virchow
       Cell Theory
       1. Cell is the basic unit of life
       2. All organisms are composed of cells
       3. All cells arise from preexisting cells

Parts of the Cell
Cell Wall (Plants only)
       Encloses all parts of the plant cell

        Primary wall – young wall, cellulose and other polysaccharides

        Secondary wall – mature wall, laid down internal to the primary wall, lignin (rigid)
        cellulose, and other polysaccharides. Used for support, protection, and water conduction
                Pathogens
                Plasmadesmata

        Middle lamella – sticky ―glue‖, pectins

Protoplast – all that is enclosed within the cell wall, membrane that surrounds everything

Cytoplasm/cytosol – liquidy part (water, ions, proteins) that the solid organelles are in

Membranes: fluid mosaic model – phospholipids and proteins, double layer that is
flexible/variable

Organelles in the protoplast:
Chloroplasts (plants only)
      Place of chlorophyll pigments

        Grana – pancake stacks, internal membranes with pigments

        Stroma – liquid portion, protein rich

        Other plastids:             leucoplasts – storage containers
                                    Chromoplasts – contain red, yellow and orange pigments
                                    Amyoplasts – starch holders

Mitochondrion (-dria, pl)—energy producer for the cell
Central Vacuole (plants only) – up to 90% of the cell volume
       Trash dump and storage center
       Acidic (ie. Lemons and limes)
       Defense and pigment purposes too

Nucleus – site of inheritable material (chromosomes), brain of the cell
      Double membrane

Nucleolus – ribosome maker found in the nucleus

Internal Membrane system
        ER
             Rough – ribosomes sites of protein synthesis
             Smooth – transport and packaging of proteins and lipids

       Golgi apparatus – storage modification and packaging of proteins produced by the ER

								
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