Transcript chapter3_part1

Molecules of Life
Chapter 3 Part 1
Impacts, Issues:
Fear of Frying
 Trans fats in hydrogenated
vegetable oil raise levels of
cholesterol in our blood more
than any other fat, and directly
alter blood vessel/harden
arteries – atheroslcerosis
 Trans fats are found in red
meats, chocolate, and large
amounts in hydrogenated oils
(cakes, cookies, etc.)
3.1 Carbon – The Stuff of Life
 Organic molecules (macromolecules, molecules
of life) are complex molecules of life, built on a
framework of carbon atoms
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Carbohydrates - simple sugar/mono (glucose)
Lipids - fatty acids
Proteins – amino acids
Nucleic acids - nucleotides
Carbon – The Stuff of Life
 Carbon atoms can be assembled and
remodeled into many organic compounds
• Can covalently bond with one, two, three, or four
atoms
• Can form polar or nonpolar bonds
• Can form chains or rings
3.2 From Structure to Function
 The function of organic molecules in biological
systems begins with their structure
 The building blocks of carbohydrates, lipids,
proteins, and nucleic acids bond together in
different arrangements to form different kinds of
complex molecules
Functional Groups
 Hydrocarbon
• An organic molecule that consists only of
hydrogen and carbon atoms; hydrophobic
 Most biological molecules have at least one
functional group – Know structure and group
• A cluster of atoms that imparts specific chemical
properties to a molecule
Common Functional Groups
in Biological Molecules
Effects of Functional Groups:
Sex Hormones
What Cells Do with Organic Compounds
 Metabolism
• Activities by which cells acquire and use energy
to construct, rearrange, and split organic
molecules
• Allows cells to live, grow, and reproduce
• Requires enzymes
What Cells Do to Organic Compounds
 Condensation
• Covalent bonding of two molecules to form a
larger molecule (polymer)
• Produces two water molecules and a polymer
• Study figure 3.6
 Hydrolysis aka Cleavage
• The reverse of condensation
• Cleavage reactions splits or breaks down larger
molecules (polymers) into smaller ones
(monomers)
• H2O added
What Cells Do to Organic Compounds
 Monomers
• Molecules used as subunits to build larger
molecules (polymers)
 Polymers
• Larger molecules (macromolecules) that are
composed of smaller units called monomers
• May be split and used for energy
Condensation and Hydrolysis
Animation: Condensation and hydrolysis
3.3 Carbohydrates
 Carbohydrates are the most plentiful biological
molecules in the biosphere
 Cells use some carbohydrates as structural
materials; others for stored or instant energy
Carbohydrates
 Carbohydrates
• Organic molecules that consist of carbon,
hydrogen, and oxygen in a 1:2:1 ratio
 Three types of carbohydrates in living systems
• Monosaccharides – glucose, ribose, fructose
• Oligosaccharides – lactose, sucrose (most
plentiful sugar)
• Polysaccharides – starch (plants), cellulose,
glycogen (animals)
Simple Sugars
 Monosaccharides
(one sugar unit) are
the simplest
carbohydrates
• Used as an energy
source
• Backbones of 5 or 6
carbons
• Dissolves in H2O
because H2O forms
H+ bonds with OHgroup
Short-Chain Carbohydrates
 Oligosaccharides
• Short chains of monosaccharides
• Example: sucrose, a disaccharide
Complex Carbohydrates
 Polysaccharides
• Straight or branched chains of many sugar
monomers
 The most common polysaccharides are
cellulose, starch, and glycogen
• All consist of glucose monomers
• Cellulose – cell walls of plants
• Starch – plants store excess carbs in the form of
starch
• Glycogen – energy storage in animals.
Cellulose, Starch, and Glycogen
Chitin
 Chitin
• A nitrogen-containing polysaccharide that
strengthens hard parts of animals such as crabs,
and cell walls of fungi
3.4 Greasy, Oily – Must Be Lipids
 Lipids function as the body’s major energy
reservoir, and as the structural foundation of cell
membranes
 Lipids
• Fatty, oily, or waxy organic compounds that are
insoluble in water
Fatty Acids
 Many lipids incorporate fatty acids
• Simple organic compounds with a carboxyl group
joined to a backbone of 4 to 36 carbon atoms
 Essential fatty acids are not made by the body
and must come from food
• Omega-3 and omega-6 fatty acids
Fatty Acids
 Saturated,
monounsaturated,
polyunsaturated
Fats
 Fats
• Lipids with one, two, or three fatty acids “tails”
attached to glycerol
 Triglycerides
• Neutral fats with three fatty acids tails attached to
glycerol
• The most abundant energy source in vertebrates
• Insulator (adipose tissue in penguins and
humans)
• Study Figure 3.11a (ppts)
glycerol
+ 3H2O
triglyceride, a neutral fat
three fatty acid tails
Fig. 3-11a, p. 42
Saturated and Unsaturated Fats
 Saturated fats (animal fats)
• Fatty acids with only single covalent bonds
• Packed tightly; solids at room temperature
 Unsaturated fats (plant fats)
• Fatty acids with one or more double bonds
• Kinked; liquids at room temperature (oils)
Phospholipids
 Phospholipids
• Molecules with a polar head containing a
phosphate and two nonpolar fatty acid tails
• Heads are hydrophilic, tails are hydrophobic
• Study Figure 3.14
Waxes
 Waxes
• Complex mixtures with long fatty-acid tails
bonded to long-chain alcohols or carbon rings
• Protective, water-repellant covering ( cuticle of
fruits and vegetables).
• Dehydration
Cholesterol and Other Steroids
 Steroids/Sterols
• Lipids with a rigid backbone of four carbon rings
and no fatty-acid tails
 Cholesterol
• Component of eukaryotic cell membranes
• Remodeled into bile salts, vitamin D, and sex
hormones (estrogen and testosterone)
Animation: Fatty acids
Animation: Secondary and tertiary
structure
Animation: Structure of an amino acid
Animation: Structure of ATP
Animation: Structure of starch and
cellulose
Animation: Sucrose synthesis