essentials chapter 3 the molecules of life
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8/8/2019 Essentials Chapter 3 the Molecules of Life
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Chemical Compounds of Life
Chapter 3
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Biologically important compounds
Organic and Inorganic compounds:
± Organic ± contain carbon ± occur naturally in
living things. Also contain H,O, and N
Less frequently ± P,S,Fe,Ca,Na,Cl,Mg and K.
± Inorganic do not contain carbon ± except
carbon dioxide, carbon monoxide and calcium
carbonate. Water,carbon dioxide,salts,inorganic bases and
acids commonly found in living things
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Inorganic compounds: Water
Properties of Water
± Cohesion ± water as a polar molecule - force
of attraction between molecules of the same
substance
± Adhesion ± attraction between molecules of
one substance and molecules of another
substance ± why water is one of the bestsolvents.
± Capillary action
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Organic compounds
Four types:
± Carbohydrates
± Proteins ± Lipids
± Nucleic Acids
± Looking at structure and function
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Carbohydrates
Contain C,H,O
H, O always in a 2:1
ratio
Building blocks ±
simple sugars called
monosaccharides
Names end in ³ose´ Importance ± contain
large amounts of
energy
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Carbohydrates
Simplest sugar = glucose = monosaccharide (mono =one)
Monosaccharide + monosaccharide disaccharide(double sugar)
Polysaccharide (many sugars) = mono + mono + mono+di + disaccharide.
Polymers are large molecules consisting of repeatingsubunits (monomers)
Excess sugar stored as a polysaccharide in
organisms:Plants: store starch ± a polysaccharide (seeds, roots
and stems
animals: store glycogen ± a polysaccharide in theliver and muscles
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How organic compounds are
synthesized and broken down Hydrolysis: Large complex molecules are broken
down into simpler ones. Water must be presentduring the reaction.
AB
+ water -
A +B
Complex + water = simple + simple
Dehydration synthesis : small molecules arebonded together to make more complexmolecules
A + B - AB + water » Simple + simple = complex + water
Enzymes are organic catalysts ± they must be present for allchemical reactions to occur in living things.
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disaccharides
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Carbohydrates
Function as a source of energy in living
things.
Function in structure: ± Polysaccharides:
± Chitin ± exoskeleton of insects
± Cellulose ± cell walls of plant cells.
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Lipids
Fats, oils and waxes
Contain C,H,O ± less oxygen in lipids
Function in cell structure ± cellmembranes
Some hormones are lipids
reserve energy supply ± Plants store oils in seeds
± Animals store fat under skin for insulation and
reserve energy source in fat cells
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Lipids
Fats and oils are made up of glycerol and
fatty acids.
± Glycerol is a 3 carbon compound with an OHbonded to each carbon
± Fatty acids are chains of carbon and
hydrogen with a carboxyl group at the end
± (COOH) ± Dehydration synthesis of a fat produces a fat
and 3 water molecules
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Lipids
fatty acid
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Lipids
Fats can be saturated or unsaturated
± Saturated ± solid at room temperature, single
bonds in carbon chain ± butter, lard, bacon
grease
± Unsaturated ± liquid at room temperature,
double bonds in carbon chain - oils
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LE 5-12a
Saturated fat and fatty acid.
Stearic acid
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LE 5-12b
Unsaturated fat and fatty acid.
Oleic acid
cis double bondcauses bending
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Fats made from unsaturated fatty acids are calledunsaturated fats
Plant fats and fish fats are usually unsaturated
Plant fats and fish fats are liquid at room
temperature and are called oils
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Unsaturated fat
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LE 5-11b
Fat molecule (triacylglycerol)
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Steroids
Steroids are lipids characterized by a carbonskeleton consisting of four fused rings
Cholesterol, an important steroid, is a component
in animal cell membranes
Although cholesterol is essential in animals, high
levels in the blood may contribute to
cardiovascular disease
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Saturated fats
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Phospholipids
Phospholipids make up the plasma
membrane all living things. They are made
up of a glycerol molecule and 2 fatty acids
plus a phosphate group.
The cell membrane is called a
phospholipid bilayer
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LE 5-14
WATERHydrophilichead
Hydrophobic
tailsWATER
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LE 5-13
Structural formula Space-filling model Phospholipid symbol
Hydrophilic
head
Hydrophobictails
Fatty acids
Choline
Phosphate
Glycerol
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Proteins
Contain C,H,O,N (some contain S)
Amino acids are the building blocks ± 20
different amino acids
Structural parts of cells and body tissues Hormones ± chemical messengers
Enzymes ± catalysts for chemical reactions
Antibodies ±protect organisms against disease.
Examples of some proteins ± insulin (regulates
blood sugar levels)- hemoglobin ±in red blood
cells (carries oxygen to body cells)
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Structure of proteins
Made of amino acids bonded together
forming dipeptides and polypeptides ± the
bond is called a peptide bond
Amino acids have distinct makeup
± Amino group
± Carboxyl group
± R group ± variable group
± Central carbon atom
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Formation of a dipeptide
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Protein structure
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Nucleic Acids
Deoxyribonucleic acid - DNA
Ribonucleic acid - RNA
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DNA
Hereditary material Made up of building blocks called
nucleotides
± Nucleotides ± sugar, phosphate, nitrogenousbase
Sugar = deoxyribose
Phosphate PO4
Nitrogenous base (4) = adenine, guanine,cytosine, thymine
± Purines = adenine and guanine
± Pyrimidines = cytosine and thymine
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nucleotide
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Structure of DNA
Adenine bonds to
thymine
Guanine bonds to
cytosine
DNA is a double helix
± Double stranded ± a
polymer of nucleotides
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RNA
Ribonucleic Acid
± Single strand
± Involved in protein
synthesis ± Polymer of nucleotides
Sugar = ribose
Phosphate = PO4
Nitrogenous bases (4)
± Adenine
± Cytosine
± Guanine
± Uracil
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From DNA to RNA to Protein