MACROMOLECULES/
BIOMOLECULES
Molecules found in living organisms
Macromolecules are organic
•Organic molecules – carbon-
containing molecules e.g., CH4
•Why is life C-based?
•C has 6 electrons (2, 4). To fill its
valence shell, it has to form 4
covalent bonds
•C can combine with diverse atoms
using single or double covalent
bonds to form a variety of
molecules – versatile
Macromolecules are polymers made of
monomers
•Macromolecule is like a long train
(polymer) made of small cars (monomers)
that are connected in a specific manner by
bonds
•E.g., starch is a polymer made of the
monomer glucose
Macromolecules are polymers made of
monomers
•Monomers combine to form polymers using dehydration
reaction (removal of water)
Macromolecules are polymers made of
monomers
•Polymers breakdown to form monomers using hydrolysis
reaction (addition of water)
Comprehension check
•What type of reaction is this?
1. Hydrolysis
2. Dehydration
Functional groups
•Groups of bonded atoms with specific
chemical properties
•E.g.
•-OH – in carbs
•-COOH – in proteins, lipids
•-NH2 – in proteins
•-SH – in some proteins
•-PO43- – in DNA, RNA
4 Macromolecules
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids
CARBOHYDRATES
Introduction
•Contain C, H & O (CH2O);
•e.g., Glucose (C6H12O6)
•Function:
•Primary source of energy
•Building blocks (e.g., in DNA)
•Provide structural support (e.g., cellulose)
•Structure:
•Hydrophilic
•Monomers – monosaccharides
•Polymers – polysaccharides
Monosaccharides (“one sugar”)
•Simplest carbs (3-6 C
atoms)
•Glucose – energy drinks,
honey
•Fructose – fruits, honey
•Drawn in linear or ring
form
Disaccharides (“two sugars”)
•Formed by dehydration reaction
between 2 monosaccharides
•E.g.
•Lactose (milk) = Glucose + Galactose
•Sucrose (sugar) = Glucose + Fructose
•Maltose = Glucose + Glucose
Polysaccharides (“many sugars”)
•Complex carbs
•Formed by dehydration reaction between > 2 monosaccharides
•Starch – energy storage molecule in plants
•Glycogen – energy storage molecule in animals
•Cellulose – gives structure to plants; most abundant organic
molecule on Earth
•Agar – extracted from red algae
Polysaccharides
Comprehension check
•Which of the following is NOT a polymer?
1. Starch
2. Fructose
3. Cellulose
4. Glycogen
5. Peptidoglycan
LIPIDS
Introduction
•Contain C, H & O
•Function:
•Source of energy
•Provide insulation
•Act as hormones
•Form membranes
•Structure:
•Hydrophobic (uncharged)
•Not polymers
Types of lipids
•Triglycerides (Fats/Oils)
•Diglycerides (Phospholipids)
•Sterols
1. Triglycerides
•Structure:
•1 Glycerol – 3-C molecule (head)
•3 Fatty acids (FA) – long hydrocarbon
chains made of C & H atoms (tails)
•Function:
•Energy store – fats, 9 cal/g vs
carbohydrates, 4 cal/g
•Provide insulation as body fat
1. Triglycerides – Saturated vs.
Unsaturated
•Saturated fats:
•Contain FAs with no C = C
double bonds
•Saturated FAs are straight,
pack tightly, & therefore
solid at RT
•Unsaturated fats:
•Contain FAs with C = C
double bonds
•Unsaturated FAs are bent,
pack loosely, & therefore
liquid at RT
2. Diglycerides
•Structure:
•1 Glycerol + 1 phosphate group
(hydrophilic head)
•2 FA tails (hydrophobic tails)
•Amphipathic
•Heads face water and tails tuck away
from water
•Function:
•Important part of plasma membrane,
layer that surrounds cells
3. Sterols
•Structure:
•4 C-containing rings
•Diverse functional groups on rings
•Function:
•Stabilize plasma membranes
•Act as hormones, e.g., estrogen,
testosterone
•Are these found in bacteria?
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