Essential Elements

20-25% of elements

Necessary for life

C, H, O, N make up 96% of living matter

25 in humans

Chapter 5- Macromolecules

Monomers & Polymers

Repeating subunits are bonded to create a large (macro-) molecule

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

Dehydration (condensation) and hydrolysis Demo

Carbohydrates

Carbohydrates

sugars, starches

source of energy & structure

may be: mono-, di- or polysaccharides

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

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.

Fats (cont.)

Trans-fats...

What do you know about these?

Why are they dangerous?

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

Hydrophilichead

Hydrophobictail

WATER

WATER

STEROIDS

Four fused rings

Chemical groups attached determine function

Ex. Cholesterol, hormones, Vitamin D

Proteins

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

**No characteristic C:H:O ratio

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)

Dehydration Synthesis

Primary Structure

sequence of amino acids

linear

peptide bonds

Primary structure

Aminoacids

Amino end

Carboxyl end

Primary structure of transthyretin

Secondary Structure

Alpha helix or beta pleated sheet

hydrogen bonds

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

Quaternary Structure

final structure

determines function

arrangement of 2 or more polypeptides

Hemoglobin

HemeIron

α subunit

α subunit

β subunit

β subunit

Collagen

Quaternary Structure

final structure

determines function

arrangement of 2 or more polypeptides

Structure : Function

Denaturation

Non-optimal temperatures and pH levels can break bonds; change proteins shape

Nucleic Acids

Nucleic Acids

C, H, O, N, P

Monomer: nucleotide

Nucleotides are made of a sugar, phosphate, nitrogen base

Examples- DNA, RNA, ATP

RNA vs. DNA

RNA vs. DNA

Bonding in Nucleic Acids

Phosphodiester bonds form from dehydration synthesis; create polymer

DNA as a polymer

ATP

Adenosine triphosphate

Adenosine diphosphate

pH Presentation

pH Basics

pH = potential hydrogen

Acids give off H+/H3O+ in H2O

Bases give off OH- or accept H+/H3O+

Dissociation

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*

Neutralization

Buffer Solutions

A solution that resists pH change when small amount of acid or base are added.

Ex. Human blood (7.35-7.45)