BIO1011 Lecture Notes - Lecture 4: Hydrogen Bond, Covalent Bond, Major Minor Records
BIO1011
Macromolecules
Macromolecules
Chemical Elements
•There are 92 elements in the periodic table
•16 occur in all organisms
•23 occur in living matter
•Just 4 make the majority (99%) of cell mass (C, H, O, N)
•In organisms:
Chemical Bonds
•Carbon, hydrogen, nitrogen and oxygen all form covalent bonds with one another.
•These are the strongest bonds we know of.
-Covalent Bonds
•Consist of a shared pair of electrons to fill the outer orbit/shell of an atom
•A molecule is a cluster of atoms held together by covalent bonds, in which
electrons are shared rather than transferred between atoms.
•There can be multiple covalent bonds i.e, single, double, triple etc.
•A single covalent bond is between two electrons, a double is between four, a
triple is between six etc.
•The lighter the element, the stronger the bond
NOTE: Number of electrons needed to fill outer shell:
-H=1
-O=2
-N=3
-C=4
Hydrogen Bonds
•(technically is not a bond, but a weak electrostatic reaction)
•Hydrogen bonds do not link hydrogen atoms. Hydrogen bonds are linkages between
atoms that electrostatic (polar) attraction
•Oxygen atoms are highly electronegative, creating polarity in a single water molecule
•When a positively charged region of one water molecule comes close to a negativity
charged region of a second water molecule, the electrical attraction between them can
establish a weak bond called hydrogen bond.
Hydrophilic- water loving
Hydrophobic- water hating
MAJOR
MINOR
TRACE
H- Hydrogen
P- Phosphorus
Mn- Magnesium
O- Oxygen
S- Sulfur
Fe- Iron
C- Carbon
Ca- Calcium
Co- Cobalt
N- Nitrogen
Na- Sodium
Cu- Copper
K- Potassium
Zn- Zinc
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BIO1011
Macromolecules
Types of Reactions
-Condensation Reaction
•makes bonds
•releases water
•occurs when a bond is formed between an –OH group on one sugar and an –OH
group on another. Water is expelled as the bond is formed.
•is an anabolic reaction, i.e it builds molecules
-Hydrolysis
•breaks bonds
•is the chemical breakdown of a compound due to a reaction with water
•it is a catabolic reaction, i.e it breaks down molecules
-Electrostatic Attractions
•Residual attractive or repulsive forces between molecules or atomic groups that do
not arise from a covalent bond
ORGANIC MOLECULES
•Are large molecules made up of smaller sub-units.
•All organic molecules contain carbon.
Monomer: the subunit that constructs giant polymeric macromolecules within a cell.
E.g
•Sugars
•Fatty acids
•Amino acids
•Nucleotides
Polymer: The result of many monomers coming together
•polys -many meris - part
•Monomers are connected by condensation reactions (dehydration)
•Polymers are disassembled by hydrolysis (hydro -water, lysis -break)
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BIO1011
Macromolecules
Carbohydrates
•Carbohydrates are the most abundant organic compound in nature, and provide fuel and
structure for living organisms
•Composed of carbon, hydrogen and oxygen.
•Usually have the general formula of CnH2nOn
Monosaccharides
(Monos - single, sacchar - sugar)
•Are the smallest carbohydrate units
•Monosaccharides (sugars) are the monomers of
polysaccharides (carbohydrates)
•Monosaccharides have ring structures in water
•They are single, simple sugars (aldoses/ketoses)
•E.g fructose, glucose, ribose and deoxyribose
•Glucose is the most important monosaccharide. It
is hexose (6 carbons).
• C6H12O6
•Glucose can be ‘alpha’ or ‘beta’ depending on the
location of the OH group on the ring
Disaccharides
•Two monosaccharides joined by condensation
•Creation produces water
•E.g sucrose (glucose + fructose)
• lactose (glucose + galactose)
• maltose (glucose + glucose)
•An oligosaccharide is a smaller polysaccharide
Polysaccharides
•are polymers of more than two molecules
•they are often very long and may be branched
•glycosidic bonds that hold the sugars together
can be 1-4 or 1-6
•Starch
-Made of alpha glucose monomers
-Polymer is helical in shape
-Amylose is a polysaccharide made of
glucose with 1-4 linkages
-unbranched and makes up 30% of starch
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Document Summary
Chemical elements: there are 92 elements in the periodic table, 16 occur in all organisms, 23 occur in living matter, just 4 make the majority (99%) of cell mass (c, h, o, n, in organisms: Chemical bonds: carbon, hydrogen, nitrogen and oxygen all form covalent bonds with one another, these are the strongest bonds we know of. Note: number of electrons needed to ll outer shell: Hydrogen bonds: (technically is not a bond, but a weak electrostatic reaction, hydrogen bonds do not link hydrogen atoms. Majorminortraceh- hydrogenp- phosphorusmn- magnesiumo- oxygens- sulfurfe- ironc- carbon ca- calciumco- cobaltn- nitrogenna- sodiumcu- copperk- potassiumzn- zincbio1011. Macromolecules: makes bonds, releases water, occurs when a bond is formed between an oh group on one sugar and an oh group on another. Water is expelled as the bond is formed: is an anabolic reaction, i. e it builds molecules.
