Building Blocks of Life # 7

Carbon

• the central component of organic chemistry

  • all living organisms on earth are carbon based

  • all of the biomolecules that form our cells are composed of a carbon skeleton

  • a carbon atom can form 4 covalent bonds

    • each carbon atom can act as an intersection point from which a molecule can branch off in as many as four directions

      • this allows each of its bonds to rotate freely

Form & function

• the form (shape) and chemical structure of most organic molecules have a significant effect on how they function

  • even slight changes in chemical composition can lead to the entire molecule not functioning properly, or at all

Isomers

• molecules that have the same chemical formula (except same atoms) but have different structures

  • structural

  • cis-trans

  • enantiomers

Structural isomers 

• isomers where the arrangement of atoms in the molecule differs

Cis-Trans Isomers

• isomers that include a double covalent bond (have diff arrangements of atoms on either side of the bond)

Enantiomer isomers

• isomers that are mirror images of each other

  • chiral isomers: come in left-handed and right-handed forms

  • left is homochiral (it can only use on type of isomer)

    • all life uses only left-handed amino acids and right handed nucleic acids

polymers

• long chains of component molecules called monomers, connected with covalent bonds 

  • most organic molecules are polymers

  • proteins, nucleic acids, carbohydrates, lipids

Monomers

• amino acids, nucleotides, monosaccharides, fatty acids

monosaccarides

• sugar monomer

  • glucose

  • fructose

  • galactose

proteins 

• machinery that runs cells, provides structural support, & acts as catalysts that facilitate chemical reactions 

• monomer: amino acids

nucleic acids

• encode and transmit genetic information

• monomer: nucleotides 

carbohydrates

• provide source of energy and make up the cell wall in bacteria, plants, and algae

• monomer: monosaccharides

lipids

• make up cell membranes, store energy, and act as signaling molecules 

• monomer: fatty acid

Dehydration synthesis (condensation reaction)

• joining reaction (that chains monomers together into polymers — overall called polymerization)

  • water molecules are created each time a monomer is added to the polymer chain

  • requires energy — our cells use special proteins called enzymes to facilitate chemical reactions and make it require less energy

Hydrolysis reaction

• breaking reaction (that breaks a polymer apart back into its monomers)

• to break a polymer back into monomers, a water molecule is consumed by the reaction (water molecule added back into the polymer chain and breaks a bond apart) 

• requires energy — our cells use special proteins called enzymes to facilitate chemical reactions and make it require less energy  

proteins 

• polymers, made up of individual amino acid monomers 

• its structure/shape determines its function:

  • primary, secondary, tertiary, quaternary

• contains a:

  • carboxyl group, phosphate group, amino group, r-group, peptide bond

carboxyl groups

• inside of proteins 

• C, O, OH

Amino groups

• inside proteins

• H2N

R-groups

• R

• causes protein to fold under certain circumstances

Peptide bond

• the bond created between the amino group and the carboxyl group when the dehydration synthesis reaction joins the two (takes out the OH and the H and replaces it with a bond)

primary, secondary, tertiary, and quaternary

list the 4 different protein structures/shapes

primary protein structure

• the linear chain of covalent peptide bonds

secondary protein structure 

• twisted chain of amino acids that form hydrogen bonds between the amino and carboxyl groups (single Helix) 

tertiary protein structure

• 3D folding of a protein, determined by the r-groups

hydrophobic r-groups

• cause the protein to fold into itself to avoid water

hydrophilic r-groups

• cause hydrogen bonds to form between folds, strengthening the structure

quaternary protein structure

• a protein, composed of smaller proteins (subunits)

• ex) hemoglobin

proteins

• roles:

  • catalyse reactions

  • defend / protect the cell

  • nutrient storage and transfer

  • transport - move other molecules

  • hormonal - bodily function coordination

  • receptor / detect & react

  • movement

  • structural / support

DNA (deoxyribonucleic acid)

• nucleic acid polymer

• composed of deoxyribonucleotides (nucleotide monomer)

• double stranded = double helix

• contains deoxyribose sugar

RNA (ribonucleic acid) 

• nucleic acid polymer 

• composed of ribonucleotides (nucleotide monomer) 

• single stranded 

• contains ribose sugar 

purines (nucleobases)

• Adenine (A)

• Guanine (G)

• have a double ring structure

pyrimidines (nucleobases) 

• uracil (U)

• thymine (T) 

• cytosine (C)

• have a single ring structure 

phosphodiester bond

• the kind of bond that links together nucleotides to form nucleic acid polymers

  • the phosphate group attaches to the 5’ carbon, covalently bonds with the 3; carbon through dehydration synthesis

  • these bonds makeup the backbone of nucleic acids and make the polymer resilient against heat and pH

carbohydrates 

• the fuel that keeps cells running (one of the major energy storage biomolecules) 

• these polymers can also be used for structural integrity at multiple levels

• 3 levels of complexity:

  • disaccharides, polysaccharides, glycosidic bond

disaccharides

• two monomers chemically bound together in a single compound

  • when two monosaccharides are linked by a glycosidic bond they form a ______

  • sucrose (glucose + fructose)

  • lactose (glucose + galactose)

  • maltose (glucose + glucose)

polysaccharides

• three or more monomers chemically bound into a single compound

  • many monosaccharides in various combinations and orientations

  • two primary functions:

    • energy storage

    • structural support

glycosidic bond

• covalent bonds that link monosaccharides together 

Lipids

• defined by a shared property (they are partially or completely hydrophobic) - nonpolar

• not made from repeating monomers

• not defined by a structure

neutral fats

• used for energy storage, insulation from cold, protection of internal organs

  • made up of fatty acid molecules and glycerol molecules

  • # of fatty acids per glycerol range from 1-3

    • 1=monoglyceride

    • 2=diglyceride

    • 3=triglyceride

    • * fatty acids can be saturated or unsaturated)

phospholipids 

• major constituents of our cell membranes 

• 1 glycerol, 1 phosphate group, 2 fatty acid chains

• are amphipathic 

• when exposed to water they self assemble into a bi-layer, that sheilds the hydrophobic tails from the water (hydrophobic tails on inside)

amphipathic

• have a hydrophilic head & a hydrophobic tail

steroids

• maintain the fluidity of cell membranes & signal molecules

  • based on sterol: 4 fused rings composed of 20 bonded carbon atoms

glycerol

• bonds with fatty acids via an ester bond

ester bond

• bonds together glycerol and fatty acids

saturated fatty acids

• all carbon atoms in the hydrocarbon chain are connected to each other by single covalent bonds

  • remainder of carbon bonds have an attached hydrogen

    • molecule is saturated with hydrogen

  • solid @ room temp

unsaturated fatty acids 

• when some of the carbon atoms in the hydrocarbon chain are linked by double covalent bonds 

  • missing some hydrogen atoms

    • not saturated with hydrogen

  • double bond = “kink” in the molecule, prevents molecules from stacking on top of each other

  • can occur in Cis or Trans isomers

    • trans-fats = not good for you