Lecture 4 Chemical Bonds Flashcards
Organic Molecules
contain carbon and hydrogen atoms
Biomolecules (Organic Molecules)
Carbohydrates
Lipids
Proteins
Nucleic Acids
Inorganic vs. Organic Molecules
Inorganic usually contain positive & negative ions, while Organic always contain Carbon and Hydrogen
Inorganic is usually ionic bonding, while Organic is always covalent bonding
Inorganic always contain a small number of atoms, while Organic is often quite large with many atoms
Inorganic is associated with non living matter, while Organic is associated with living organisms
Carbon
Shares well with elements
Functional Groups
clusters of specific atoms that always act the same way, bonded to the carbon skeleton with characteristic structures and functions
Isomers
organic molecules that have identical molecular formulas but a different arrangement of atoms. You would naturally expect these guys to react differently than one another in chemical reactions
Monomer & Polymer
Monomer- A repeating unit
Polymer- A Molecule composed of monomers
Ex: amino acids (monomer) are joined together to form a protein (polymer)
Dehydration Reaction
a chemical reaction in which subunits are joined together by the formation of a covalent bond and water is produced during the reaction
Hydrolysis Reaction
a chemical reaction in which a water molecule is added to break a covalent bond
Enzymes
a molecule that speeds up a chemical reaction
- Enzymes are required for cells to carry out dehydration synthesis and hydrolysis reactions.
- Enzymes are not consumed in the reaction.
- Enzymes are not changed by the reaction.
Carbohydrates
•Functions:
●Energy source
●Provide building material (structural role)
- Contain carbon, hydrogen and oxygen in a 1:2:1 ratio
- Varieties: monosaccharides, disaccharides, and polysaccharides
Monosaccharide
a single sugar molecule
•Examples:
●Glucose (transported in blood, gets broken down & converted into ATP), fructose (fruit) and galactose
•Hexoses - six carbon atoms
●Ribose and deoxyribose (in nucleic acids RNA & DNA)
•Pentoses – five carbon atoms
Disaccharide
contains two monosaccharides joined together by dehydration synthesis.
•Examples:
●Lactose (milk sugar) is composed of galactose and glucose.
●Sucrose (table sugar) is composed of glucose and fructose.
●Maltose is composed of two glucose molecules.
Polysaccharide
A polymer of monosaccharides. These are often used as short-term energy storage molecules.
•Examples:
●Starch provides energy storage in plants.
●Glycogen provides energy storage in animals.
●Cellulose is found in the cell walls of plants (most abundant carbohydrate & organic molecule on earth)
Lipids
•Lipids are varied in structure. •Large nonpolar molecules that are insoluble in water •Functions: ●Long-term energy storage ●Cell communication and regulation ●Protection
•Varieties: fats, oils, phospholipids, steroids, waxes
Triglycerides: Long-Term
Energy Storage
●Also called fats and oils
●Functions: long-term energy storage and insulation
●Consist of one glycerol molecule linked to three fatty acids by dehydration synthesis
Unsaturated and Saturated
●Unsaturated - one or more double bonds between carbons
•Tend to be liquid at room temperature
–Example: plant oils
●Saturated - no double bonds between carbons
•Tend to be solid at room temperature
–Examples: butter, lard
Phospholipids: form membranes (like cell membranes)
•Structure is similar to triglycerides
●Consist of one glycerol molecule linked to two fatty acids and a modified phosphate group
•Function: form plasma membranes
•In water, phospholipids aggregate to form a lipid bilayer.
●Polar phosphate heads are oriented towards the water.
●Nonpolar fatty acid tails are oriented away from water.
•Nonpolar fatty acid tails form a hydrophobic core.
Waxes
- Long-chain fatty acid bonded to a long-chain alcohol
- Solid at room temperature
- Waterproof
- Resistant to degradation
- Function: protection
- Examples: earwax, plant cuticle, beeswax
Proteins
•Proteins are polymers of amino acids linked together by peptide bonds.
●A peptide bond is a covalent bond between amino acids.
•Two or more amino acids joined together are called peptides.
●Long chains of amino acids joined together are called polypeptides.
•A protein is a polypeptide that has folded into a particular shape and has function.
Functions of Proteins
•Metabolism
●Most enzymes are proteins that act as catalysts to accelerate chemical reactions within cells.
•Support
●Keratin (make up hair & nails) and collagen (gives strength to ligaments, tendons & skin)
•Transport
●Hemoglobin and membrane proteins transport oxygen to cells!
•Defense
●Antibodies
•Regulation
●Hormones are regulatory proteins that influence the metabolism of cells.
•Motion
●Muscle proteins (actin & myosin) allow muscle contraction & therefore movement!
Levels of Protein Structure
•Proteins cannot function properly unless they fold into their proper shape.
●When a protein loses it proper shape, it said to be denatured.
•Exposure of proteins to certain chemicals, a change in pH, or high temperature can disrupt protein structure.
•Proteins can have up to four levels of structure: ●Primary ●Secondary ●Tertiary ●Quaternary
Four levels of protein structure
●Primary
•The sequence of amino acids
●Secondary
•Characterized by the presence of alpha helices and beta (pleated) sheets held in place with hydrogen bonds
●Tertiary
•Final overall three-dimensional shape of a polypeptide
•Stabilized by the presence of hydrophobic interactions, hydrogen bonding, ionic bonding, and covalent bonding
●Quaternary
•Consists of more than one polypeptide
Protein folding diseases
•Chaperone proteins help proteins fold into their normal shape.
●Defects in chaperone proteins may play a role in several human diseases such as Alzheimer disease and cystic fibrosis.
•Prions are misfolded proteins that have been implicated in a group of fatal brain diseases known as TSEs. (transmissible spongiform encephalopathies). Prions are hypothesized to cause other proteins to mis-fold as well, so they are kind of like bad influence proteins!
