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Essential Elements
20-25% of elements
Necessary for life
C, H, O, N make up 96% of living matter
25 in humans
Figure 5.2a
(a) Dehydration reaction: synthesizing a polymer
Short polymer Unlinked monomer
Dehydration removesa water molecule,forming a new bond.
Longer polymer
1 2 3 4
1 2 3
Figure 5.2b(b) Hydrolysis: breaking down a polymer
Hydrolysis addsa water molecule,breaking a bond.
1 2 3 4
1 2 3
Monosaccharides
simple or single sugar (monomer)
used as energy or source of carbon
hydroxyl group attached at all carbons except where carbonyl group is
may be aldose (end) or ketose (center)
ex: glucose, fructose, galactose
Figure 5.3
Aldoses (Aldehyde Sugars) Ketoses (Ketone Sugars)
Glyceraldehyde
Trioses: 3-carbon sugars (C3H6O3)
Dihydroxyacetone
Pentoses: 5-carbon sugars (C5H10O5)
Hexoses: 6-carbon sugars (C6H12O6)
Ribose Ribulose
Glucose Galactose Fructose
Carbon:Hydrogen:Oxygen
1 : 2 : 1
Composed of
C, H, O
Figure 5.4
(a) Linear and ring forms
(b) Abbreviated ring structure
12
3
4
5
6
6
5
4
32
1 1
23
4
5
6
123
4
56
Disaccharides
double sugars
two monosaccharides bonded by dehydration synthesis (glycosidic link)
used for energy & source of carbon
ex: sucrose, lactose, maltose
Figure 5.5
(a) Dehydration reaction in the synthesis of maltose
(b) Dehydration reaction in the synthesis of sucrose
Glucose Glucose
Glucose
Maltose
Fructose Sucrose
1–4 glycosidic
linkage
1–2 glycosidic
linkage
1 4
1 2
Polysaccharides
many monosaccharides joined (100s - 1000s)
used to store sugar/energy & as structural material
ex: starch, glycogen, chitin, cellulose
Figure 5.6
(a) Starch: a plant polysaccharide
(b) Glycogen: an animal polysaccharide
Chloroplast Starch granules
Mitochondria Glycogen granules
Amylopectin
Amylose
Glycogen
1 µm
0.5 µm
Figure 5.9
Chitin forms the exoskeletonof arthropods.
The structure of the chitin monomer
Chitin is used to make a strong and flexible surgical thread that decomposes after the wound or incision heals.
Figure 5.8
Cell wall
Microfibril
Cellulosemicrofibrils in a plant cell wall
Cellulosemolecules
β Glucose monomer
10 µm
0.5 µm
Lipids
Fats, oils, waxes
Don’t have technically have monomers… Why?
Hydrophobic
Primarily hydrocarbons
Fats
Used for energy storage
Made of glycerol and fatty acid
Glycerol = alcohol
Fatty acid = hydrocarbon with carboxyl
Bond between = ester link
Most fats in foods are triglycerides (3 f.a. + 1 glycerol)
Figure 5.10
(a) One of three dehydration reactions in the synthesis of a fat
(b) Fat molecule (triacylglycerol)
Fatty acid(in this case, palmitic acid)
Glycerol
Ester linkageComposed
of C, H, O
Ratio
~ 1 : 2 :very few
Fats (cont.)
Saturated
No double bonds
Usually animal products
Solid at room temp
Contribute to clogged arteries
Unsaturated
Double bonds; “kinked” structure
Usually plant products
Liquid at room temp
Usually healthier option
Figure 5.11(a) Saturated fat(b) Unsaturated fat
Structuralformula of a saturated fatmolecule
Space-fillingmodel of stearic acid, a saturatedfatty acid
Structuralformula of anunsaturated fatmolecule
Space-filling modelof oleic acid, anunsaturated fatty acid
Cis double bond causes bending.
Phospholipids
Used in cell membrane
2 fatty acids + 1 glycerol
Glycerol also has a phosphate group
Partially hydrophobic & partially hydrophilic -- WHY??
Figure 5.12Choline
Phosphate
Glycerol
Fatty acids
Hydrophilichead
Hydrophobictails
(c) Phospholipid symbol(b) Space-filling model(a) Structural formula
Hyd
roph
ilic
head
Hyd
roph
obic
tails
STEROIDS
Four fused rings
Chemical groups attached determine function
Ex. Cholesterol, hormones, Vitamin D
Proteins
Contain C, H, O, N and usually S, sometimes P
Monomers = amino acids
Amino acid order determined by mRNA strand from DNA
Proteins
Many uses in living systems:
support/structure
storage
communication
enzymes
movement
immunity
Synthesis of Protein
Dehydration synthesis
dipeptide = peptide bond forms between 2 aa
polypeptide = 100-300 aa
has N-terminal end (amine) & C-terminal end (carboxyl) —> POLAR
total protein may be one or more polypeptides
Figure 5.UN01
Side chain (R group)
Aminogroup
Carboxylgroup
α carbon
Variable R side chain-Determines function and overall protein structure
Nonpolar side chains; hydrophobic
Side chain(R group)
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)
Tryptophan(Trp or W)
Proline (Pro or P)
Polar side chains; hydrophilic
Serine (Ser or S)
Threonine (Thr or T)
Cysteine (Cys or C)
Tyrosine(Tyr or Y)
Asparagine(Asn or N)
Glutamine (Gln or Q)
Electrically charged side chains; hydrophilic
Acidic (negatively charged)
Basic (positively charged)
Aspartic acid(Asp or D)
Glutamic acid(Glu or E)
Lysine(Lys or K)
Arginine(Arg or R)
Histidine (His or H)
Secondary structure
Hydrogen bond
α helix
β pleated sheet
β strand, shown as a flat arrow pointing toward the carboxyl end
Hydrogen bond
Tertiary Structure
characteristic 3D shape of polypeptide
depends on interactions of R groups
may involve almost any bonds:
H interactions
S-S bonds (disulfide bridge)
ionic
hydrophobic interactions
Figure 5.20f
Hydrogenbond
Disulfide bridge
Polypeptide backbone
Ionic bond
Hydrophobicinteractions andvan der Waalsinteractions
Nucleic Acids
C, H, O, N, P
Monomer: nucleotide
Nucleotides are made of a sugar, phosphate, nitrogen base
Examples- DNA, RNA, ATP
pH Basics
pH = potential hydrogen
Acids give off H+/H3O+ in H2O
Bases give off OH- or accept H+/H3O+
pH Basics
pH ranges from 0-14
0-6.9 = acidic
7 = neutral
7.1-14 = basic
14 = acid pH + base pH
pH = -log [H+]
pH Examples
The concentration of hydronium ions in an aqueous solution is 10-2.76, what is its pH?
An aqueous solution has a pH of 4. What is the concentration of hydroxide ions in solution?
*A single unit change in the pH scale represents 10x*