Unit 3 : Macromolecules

Molecular Interactions

• Ionic Bond: bond formed when one or more electrons are transferred from one atom to another. The bond is held together by the attraction of a positively charged cation to a negatively charged anion.

• Covalent Bond: bond formed when atoms share a pair of electrons

• Hydrogen Bond: attractions between hydrogens and negative charged poles of OTHER molecules. hydrogen bonds are attractions between two different molecules.

• Van Der Waals Forces: temporary and random attractions between nonpolar molecules

Water’s Polarity

• Water is polar because oxygen has a higher affinity for electrons. therefore, the electrons are around the oxygen side of the molecules, making it have a partial negative charge. The hydrogen side, then, has a partial positive charge.

• Oxygen and hydrogen do not share the electron equally

• Cohesion: the attraction between molecules of the same substance. Contributes to the high surface tension of water.

• Adhesion: the attraction between molecules of different substances. contributes to the formation of a meniscus in a graduated cylinder.

• High Heat Capacity: water can absorb a lot of heat without increasing in temperature. allows water to have an insulating effect on Earth

• High Heat of Vaporization: water can absorb a lot of heat before changing into a gaseous state. allows sweat to cool us down

• Solid Water is less Dense than liquid water: this allows ice to float and keeps lakes and oceans from becoming permanently frozen.

• Water is an excellent solvent: it likes to interact with any charged or partially charged molecules. can dissolve polar covalent compounds and ionic compounds

Characteristics of Carbon

• has 4 valence electrons and can form up to 4 covalent bonds.

• can bond to other carbons, making backbones for organic molecules with infinite combinations

• carbon chains can vary in length, be branched or unbranched, have double bonds between carbons, and form rings.

4 Classes of Macromolecules

• Carbohydrates: sugars or polymers of sugars

  • elements: C, H, and O in a 1:2:1 ratio

  • monomer: monosaccharide (simple sugar)

  • polymer: polysaccharide (complex sugar)

  • Functions

    • short term energy storage

      • ex: glucose, glycogen, starch

    • structure

      • ex: chitin, cellulose

• Proteins: polymers of amino acids

  • elements: C, H, O, N, and S

  • monomer: amino acid

  • functions: numerous functions, including enzymes, transport, defense, communication, structure, movement, etc

• Lipids: non-polar, hydrophobic macromolecules

  • elements: mostly C and H

  • monomer: no true monomer

  • Types and Functions

    • fats and oils: long term energy storage (lipids can store more energy in a smaller amount of space than carbohydrates)

    • phospholipids: structure. phospholipids are the major components of cell membrane.

    • steroids: mediate physiological reactions

2 Types of Nucleic Acids

• Deoxyribonucleic Acid (DNA): hereditary material for the cell

• Ribonucleic Acid (RNA): involved in protein synthesis

Amino Acid Structure

• Amino group and carboxyl group connected by an R group’

Protein Folding

• Primary Structure: the amino acid sequence of a protein. made up of covalent bonds called peptide bonds

• Secondary Structure: hydrogen bonds in the backbone of a protein. does not involve the R groups of the amino acids. can be an a helix or a B pleated sheet

• Tertiary Structure: covalent, ionic, or hydrogen bonds between the R groups of different amino acids. gives a protein its overall shape

• Quaternary Structure: if a protein requires more than one chain to be functional, quaternary structure is how the multiple chains fit together.

Enzyme Functions

• enzymes speed up reactions by lowering the activation energy of a reaction. all biological reactions require an input of energy to start the reaction. enzymes lower that amount of energy, allowing the reaction to go more quickly.

Definitions

• Electronegativity: the affinity of an atom for electrons. oxygen has a high electronegativity and therefore has a high affinity for electrons.

• organic chemistry: chemistry involving carbon chains

• monomer: small subunits that when linked together form a polymer

• polymer: large molecules made up of small monomers linked together

• dehydration reaction: chemical reaction that joins monomers to form a polymer. also known as a condensation reaction. forms polymers

• hydrolysis reaction: chemical reaction that breaks monomers from polymers. breaks apart polymers

• monosaccharide: monomer of a carbohydrate. glucose is a monosaccharide.

• polysaccharide: polymer of a carbohydrate. glycogen, starch, chiting, and cellulose are polysaccharides

• amino acid: monomer of a protein

• Nucleotide: monomer of a nucleic acid

• carbohydrates

  • starch: energy storage polysaccharides in plants

  • glycogen: energy storage polysaccharide in animals

  • cellulose: structural polysaccharide in plants (part of their cell wall)

  • chitin: structural polysaccharide in some animals and fungi

  • glucose: energy storage monosaccharide for plants and animals

• lipids

  • fats

    • structure: glycerol and three fatty acid chains

    • function: long term energy storage

  • phospholipid

    • structure: glycerol, two fatty acid chains and a phosphate group

    • function: structure, most prevalent compound of a membrane

  • steroid

    • structure: four ring structure

    • function: mediates physiological reactions

  • all three of these are HYDROPHOBIC

Saturation

• saturated: when fatty acid chains do NOT have any double bonds between carbons

• unsaturated: when there is at least one double bond between carbons in a fatty acid chain

Denaturation

• the unfolding of a protein. it is caused by changes in temperature, pH, or salt concentration. when a protein unfolds, it cannot perform its function

Activation Energy

• the energy required to start a biological reaction. it is lowered but NOT eliminated by the presence of an enzyme

Active Site

• where the substrates (reactants) bind to an enzyme. the shape of the active site is critical to an enzyme’s function.

Enzyme

• a biological catalyst that speeds up reactions by lowering the activation energy required for the reaction to occur. enzyme are always proteins

Catalyst

• a substance that lowers the activation energy for a reaction to occur. enzymes are biological catalysts

Substrate

• reactants for enzymes. they bind to the active site of the enzyme, where the reaction occurs.