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1
Biological Macromolecules
•Much larger than other particles found in cells•Made up of smaller subunits•Found in all cells•Great diversity of functions
2
Four Classes of Biological Macromolecules
•Lipids•Polysaccharides•Proteins•Nucleic Acids
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Lipids
•Hydrophobic or amphipathic•Important for:•energy storage•membrane structure•signaling•cushioning•insulation
•Include:•fats•phospholipids•cholesterol and phytosterol•some hormones•others
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Fatty acid(palmitic acid)
Glycerol
(a) Dehydration reaction in the synthesis of a fat
Ester linkage
(b) Fat molecule (triacylglycerol)
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Structuralformula of asaturated fatmolecule
Stearic acid, asaturated fattyacid
(a) Saturated fat
Structural formulaof an unsaturatedfat molecule
Oleic acid, anunsaturatedfatty acid
(b) Unsaturated fat
cis doublebond causesbending
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(b) Space-filling model(a) (c)Structural formula Phospholipid symbol
Fatty acids
Hydrophilichead
Hydrophobictails
Choline
Phosphate
Glycerol
Hyd
rop
ho
bic
tai
lsH
ydro
ph
ilic
hea
d
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Hydrophilichead
Hydrophobictail WATER
WATER
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Polysaccharides
•Complex sugars•Polymers of monosaccharides (simple sugars)•Polysaccharides and monosaccharides are carbohydrates•Important for:•structure•storage of energy•cell identity marking
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Dihydroxyacetone
Ribulose
Ket
ose
sA
ldo
ses
Fructose
Glyceraldehyde
Ribose
Glucose Galactose
Hexoses (C6H12O6)Pentoses (C5H10O5)Trioses (C3H6O3)
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(b) Dehydration reaction in the synthesis of sucrose
Glucose Fructose Sucrose
MaltoseGlucoseGlucose
(a) Dehydration reaction in the synthesis of maltose
1–4glycosidic
linkage
1–2glycosidic
linkage
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(b) Glycogen: an animal polysaccharide
Starch
GlycogenAmylose
Chloroplast
(a) Starch: a plant polysaccharide
Amylopectin
Mitochondria Glycogen granules
0.5 µm
1 µm
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(a) and glucose ring structures
Glucose Glucose
(b) Starch: 1–4 linkage of glucose monomers (b) Cellulose: 1–4 linkage of glucose monomers
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b Glucosemonomer
Cellulosemolecules
Microfibril
Cellulosemicrofibrilsin a plantcell wall
0.5 µm
10 µm
Cell walls
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The structureof the chitinmonomer.
(a) (b) (c)Chitin forms theexoskeleton ofarthropods.
Chitin is used to makea strong and flexiblesurgical thread.
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Proteins
•Polymers of amino acids•Highly complex shape•Function is based on shape•Huge variety of functions
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Enzyme(sucrase)
Substrate(sucrose)
Fructose
Glucose
OH
H O
H2O
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Aminogroup
Carboxylgroup
carbon
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Nonpolar
Glycine(Gly or G)
Alanine(Ala or A)
Valine(Val or V)
Leucine(Leu or L)
Isoleucine(Ile or I)
Methionine(Met or M)
Phenylalanine(Phe or F)
Trypotphan(Trp or W)
Proline(Pro or P)
Polar
Serine(Ser or S)
Threonine(Thr or T)
Cysteine(Cys or C)
Tyrosine(Tyr or Y)
Asparagine(Asn or N)
Glutamine(Gln or Q)
Electricallycharged
Acidic Basic
Aspartic acid(Asp or D)
Glutamic acid(Glu or E)
Lysine(Lys or K)
Arginine(Arg or R)
Histidine(His or H)
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Peptidebond
Amino end(N-terminus)
Peptidebond
Side chains
Backbone
Carboxyl end(C-terminus)
(a)
(b)
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Polypeptidechain
Chains
HemeIron
Chains
CollagenHemoglobin
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Antibody protein Protein from flu virus
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Primarystructure
Secondaryand tertiarystructures
Quaternarystructure
Normalhemoglobin(top view)
Primarystructure
Secondaryand tertiarystructures
Quaternarystructure
Function Function
subunit
Molecules donot associatewith oneanother; eachcarries oxygen.
Red bloodcell shape
Normal red bloodcells are full ofindividualhemoglobinmoledules, eachcarrying oxygen.
10 µm
Normal hemoglobin
1 2 3 4 5 6 7
Val His Leu Thr Pro Glu Glu
Red bloodcell shape
subunit
Exposedhydrophobicregion
Sickle-cellhemoglobin
Moleculesinteract withone another andcrystallize intoa fiber; capacityto carry oxygenis greatly reduced.
Fibers of abnormalhemoglobin deformred blood cell intosickle shape.
10 µm
Sickle-cell hemoglobin
GluProThrLeuHisVal Val
1 2 3 4 5 6 7
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Normal protein Denatured protein
Denaturation
Renaturation
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Nucleic Acids
•Polymers of nucleotides•also called polynucleotides
•Store and convey information•Instruction manual of the cell
•Include:•DNA (deoxyribonucleic acid)•RNA (ribonucleic acid)
•Important for:•reproduction of cells•production of proteins
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5 end
Nucleoside
Nitrogenousbase
Phosphategroup Sugar
(pentose)
(b) Nucleotide
(a) Polynucleotide, or nucleic acid
3 end
3C
3C
5C
5C
Nitrogenous bases
Pyrimidines
Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA)
Purines
Adenine (A) Guanine (G)
Sugars
Deoxyribose (in DNA) Ribose (in RNA)
(c) Nucleoside components: sugars
29
Sugar-phosphatebackbones
3' end
3' end
3' end
3' end
5' end
5' end
5' end
5' end
Base pair (joined byhydrogen bonding)
Old strands
Newstrands
Nucleotideabout to beadded to anew strand
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mRNA
Synthesis ofmRNA in thenucleus
DNA
NUCLEUS
mRNA
CYTOPLASM
Movement ofmRNA into cytoplasmvia nuclear pore
Ribosome
AminoacidsPolypeptide
Synthesisof protein
1
2
3
31