BI111 Lecture Notes - Lecture 1: Starch, Parathyroid Gland, Amphiprioninae
Biology 2015 exam Grade 12
Biochemistry Unit
Ionic bonds are strong because they form crystal lattices. A Crystal lattice is when positive and negative
ions arrange themselves into an ionic crystal lattice. They are held by the balance of attractive bonds and
electrical repulsion. (each ion had the greatest possible number of oppositely charged ions close, while
keeping ions with the same charge as far as possible.
Polar covalent bond: a covalent bond formed between atoms with different electronegativity’s.
LIKE DISSOLVES LIKE
Polar solvents dissolves polar solvents (exp. Water and ionic compounds)
Non polar solvents dissolve non polar solvents (example oil in gasoline)
OIL AND WATER DO NOT DISSOLVE
Exp. SOAP:
Ions: Elements that have gained/lost electrons
Ionic bonds: between metals and non-metals
Covalent bonds: form between non-metals sharing electrons
• Based on difference in electronegativity (how strongly they attract electrons)
• Bonds with electronegativity between 1.7-4.1 have ionic characteristics and bonds below 1.7 have
covalent characteristics
Polar molecules: slightly charged (exp. Water)
Non-polar molecules: uncharged (exp. Oil)
*Water + oil= do not mix
Polar covalent: elements with different electronegativity values
Non-polar covalent: elements have the same electronegativity vales. Also has a symmetrical shape that
cancels out electronegative differences.
• Linear (polar and non-polar)
• Bent Linear (polar)
• Pyramidal (polar)
• Tetrahedral (polar and non polar)
Hydrophilic: dissolves, mixes in water- aka likes water
Hydrophobic: fails to mix with water- aka doesn’t like water
Intermolecular Forces: weaker attractions between different molecules, often due to different functional
groups, ions or hydrogen bonds
• Hydrogen bonding is in charge of DNA structure
Intramolecular Forces: the covalent bond that holds the atoms of a molecule together and the ionic bond
that holds ions together in a salt
• Presence of different functional groups will influence how the molecule works
o Groups of other elements that attach
o Can result in intermolecular forces or change solubility of a molecule
Group
Chemical formula
Structural formula
Found in
Hydroxyl
OH
Alcohols (Ethanol)
Carboxyl
COOH
Acids (Vinegar)
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Amino
NH2
Bases (ammonia)
Sulfhydryl
SH
Rubber
Phosphate
PO4
ATP
Carbonyl
COH
CO
Aldehydes
Ketones
Making Macromolecules→
Anabolic reaction: Building larger molecules from smaller pieces requires energy and results in water
production
• Condensation reaction (or dehydration synthesis)
• One H and one OH (H2O) are removed
• Can be reversed in a hydrolysis reaction (catabolic) – adding water and releasing energy
• Requires enzymes
Carbohydrates→
• Most common organic compound
• Products of photosynthesis
• Source of energy and a building material for cells
1. Monosaccharide’s
• Single sugar molecules made up of C,H and O
• Simple sugars that have a single chain of C atoms with H and OH groups attached
• Names are based on number of carbons (exp. Triose, pentose, hexose)
• Distinguished by carbonyl group (Aldehyde or ketone)
• Linear structure till dissolved in water- turns into ring structure
• Arrangement of the atoms is important
• Absorbed as energy
• Isomers: molecules with the same number of atoms but in different arrangement
• Example:
o Glucose
o Fructose
o Galactose
2. Disaccharides
• Two simple sugars attached by condensation reaction
C6H12O6
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• Forms glycosidic bond
• Common disaccharides→ Maltose (2 glucose molecules), Lactose (glucose and galactose
molecules), sucrose (glucose and fructose molecules)
• Glycosidic linkages: covalent bonds holding monosaccharide’s to one another that is formed by
condensation reaction in while H atom comes from a hydroxyl group of one sugar and the OH
group comes from a hydroxyl group of the other
3. Polysaccharides
• Many simple sugars linked into large branching chains
• Common examples: starches (grains like bread) and cellulose
• 2 common functions:
o Energy storage: starch and glycogen (animal version of starch)
o Structural support: cellulose and chitin
• The more complex the carbs, the longer they take to break down
• Glycogen: energy storage molecule in animals, similar to starch in plants; Cellulose: insoluble
substance that is the main component of plant cell walls
o Both differ only in the type of bond that holds the individual sugars together
o The difference is why humans cant digest cellulose (you can digest glycogen but not
cellulose because of the glycosidic bond)
Proteins→
• Most diverse molecules in living organisms, used in almost all cell activities
o Alter rates of metabolic reactions (enzymes)
o Transport materials in cells or body (hemoglobin)
o Structural proteins (keratin)
o Blood clotting (fibrin)
o Make up bones, skin, tendons (collagen)
• Are coded directly from DNA; they are polymers made up of amino acids (polypeptides)
• Unique sequence of amino acids connected by peptide bonds
• Proteins can vary in length from 3-4500 amino acids long
• Amino acids are organic molecules that has a central C atom sounded by
o Amino and carboxyl group (amphiprotic)
o Hydrogen
o Side chain of variable length- represented R
• ** Structure/shape determines function – key to a protein**
Primary structure- sequence of amino acids in the protein
o Biggest influence on structure and function
Secondary structure- folding and coiling of a poly peptide chain
1. a – helix: Coil formed when it bonds form between carboxyl, amino groups of amino
acids
2. B- pleated sheet: when 2 parts of a protein chain lie parallel to each other and connect
H bonds
Tertiary structure- additional folding (super coiling) of the strand as different R groups
o Forces that determine this structure
▪ Hydrogen bonds (between polar amino acids)
▪ Ionic bonds (between oppositely charged R groups)
▪ Disulfide bridges
▪ Van der Wals forces – aka London forces (between non- polar amino acids)
Quaternary structure- if two or more polypeptides all combine to form a functional protein
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Document Summary
Ionic bonds are strong because they form crystal lattices. A crystal lattice is when positive and negative ions arrange themselves into an ionic crystal lattice. They are held by the balance of attractive bonds and electrical repulsion. (each ion had the greatest possible number of oppositely charged ions close, while keeping ions with the same charge as far as possible. Polar covalent bond: a covalent bond formed between atoms with different electronegativity"s. Non polar solvents dissolve non polar solvents (example oil in gasoline) Covalent bonds: form between non-metals sharing electrons: based on difference in electronegativity (how strongly they attract electrons, bonds with electronegativity between 1. 7-4. 1 have ionic characteristics and bonds below 1. 7 have covalent characteristics. Non-polar covalent: elements have the same electronegativity vales. Also has a symmetrical shape that cancels out electronegative differences: linear (polar and non-polar, bent linear (polar, pyramidal (polar, tetrahedral (polar and non polar) Hydrophilic: dissolves, mixes in water- aka likes water.
