Monomers, polymers, and macromolecules There are 4 categories of macromolecules: Carbohydrates Proteins, Lipids, and Nucleic acids.

Monomers, polymers, and macromolecules

There are 4 categories of macromolecules:Carbohydrates

Proteins,Lipids,

and Nucleic acids

Carbon is the central element

• All biomolecules contain a Carbon chain or ring

• Carbon has 4 outer shell electrons (valence = 4)

• Therefore it’s bonding capacity is great

• It forms covalent bonds –hence, has strong bonds

• Once bound to other elements (or to other

Carbons), it is very stable

Carbon linkages

• Single chains• Rings

Propane

The 4 types of biomolecules often consist of large carbon chains

= C3H8

CH4 =

Carbon binds to more than just hydrogen!!

• To OH groups in sugars

• To NH2 groups in amino acids

• To H2PO4 groups of nucleotides of DNA, RNA, and ATP

Amino acid

OH, NH2, PO4 are called ‘functional groups’!

Fig. 3.1

Functional groups:

Isomers have the same molecular formulas but different structures

• Structural isomerStructural isomer = difference in the C skeleton structure

• StereoisomerStereoisomer = difference in location of functional groups

EnantiomersEnantiomers are special types of stereoisomers

Enantiomers are mirror images of each other

One such enantiomer contains C bound to 4 different molecules and is called a chiralchiral molecule

Chiral molecules rotate polarized light to the right (D formD form) or to the left (L L formform) molecules

Examples: amino acids (L form)

sugars (D form)

Monomers and polymers

• Monomers are made into polymers via dehydration reactions

• Polymers are broken down into monomers via hydrolysis reactions

Fig. 3.3

Carbohydrates (or sugars)

• Simple sugars (monosaccharides)

• Only one 3-C, 5-C, 6-C chain or ring involved

Fig. 3.5

Examples of sugar monomers*

*Remember how C’s are counted within the ring structures (starting from the right side and counting clockwise)

Carbohydrates (sugars)

• Double sugars (disaccharides)

• Two 6-C chains or rings bonded together

Carbohydrates (sugars)

• Complex carbo’s (polysaccharides)– Starch– Cellulose– Glycogen– Chitin

Glycogen to glucose in animals

Fig. 3.9 Polysaccharides

Starch structure vs Glycogen structure

Fig. 3.10

Polysaccharides: Cellulose structure

Proteins• Composed of chains

of amino acids

• 20 amino acids exist

• Amino acids contain– Central Carbon

– Amine group

– Carboxyl group

– R group

Fig. 3.20

The 20 Amino Acids

All differ with respect to their R group

Peptide bondsPeptide bonds occur between amino acids

• The COOH group of 1 amino acid binds to the NH2 group of another amino acid

• Forms a peptide bondpeptide bond!

Fig. 3.21

The chain (polymer) of amino acids forms a variety of loops, coils, and folded sheets from an assortment of bonds and attractions between amino acids within the chain(s)

There are at least 7 functions of proteins

• Enzyme catalysts – specific for 1 reaction• Defense – antibody proteins, other proteins• Transport- Hgb, Mgb, transferrins, etc• Support – keratin, fibrin, collagen• Motion – actin/myosin, cytoskeletal fibers• Regulation- some hormones, regulatory proteins

on DNA, cell receptors• Storage – Ca and Fe attached to storage proteins

Fig. 3.18

There are four levels of protein structure

• Primary = sequence of aa’s

• Secondary = forms pleated sheet, helix, or coil

• Tertiary = entire length of aa’s folded into a shape

• Quaternary = several aa sequences linked together

Fig. 3.23

Motifs and Domains: Important features of 2° and 4° structure

Nucleic acids: DNA and RNA

• DNA = deoxyribonucleic acid

• DNA is a double polymer (chain)

• Each chain is made of nucleotides

• The 2 chains bond together to form a helix

DNA nucleotidesnucleotides• Each nucleotide in

DNA contains:– 5-C sugar

(deoxyribose)

– Phosphate

– Nitrogen base

-adenine (A)

-guanine (G)

-cytosine (C)

-thymine (T)

Fig. 3.14

One polymer of nucleotides on one “backbone” of nucleic acid

Fig. 3.15

The DNA “double helix”

Lipids: Hydrophobic molecules

• Central core of glycerol

• Bound to up to 3 fatty acid chains

• They exhibit a high number of C-H bonds – therefore much energy and non-polar

• When placed in water, lipids spontaneously cluster together

• They help organize the interior content of cells “phospholipids”

Glycerol and fatty acid chains

What specific bonds form between glycerol and each fatty acid chain?

Would you think this to be an hydrolysis or a dehydration synthesis rxn?

Saturated and unsaturated fats

The difference resides in the number of H’s attached to C’s in the fatty acid chains; the amount of “saturation” on the C’s

Saturated vs unsaturated fats and diet• Saturated fatsSaturated fats raise LDL-cholesterol levels in the

blood (animal fats, dairy, coconut oil, cocoa butter)

• Polyunsaturated fatsPolyunsaturated fats leave LDL-cholesterol unchanged; but lower HDL-cholesterol (safflower and corn oil)

• Monounsaturated fatsMonounsaturated fats leave LDL and HDL levels unchanged (olive oil, canola, peanut oil, avocados)

• One variety of polyunsaturated fat (Omega-3 fatty Omega-3 fatty acidsacids) guards against blood clot formation and reduce fat levels in the blood (certain fish, walnuts, almonds, and tofu)

Phospholipids and cell membranes

• P-lipids make up the majority of cell membranes including:– The plasma membrane– Nuclear envelope– Endoplasmic reticulum (ER)– Golgi apparatus– Membrane-bound vesicles

Structure of single P-lipid

The 3 C’s of glycerol are bound to:

2 fatty acid chains

phosphate

Cell environment organizes P-lipid bilayer to proper orientation

Hydrophilic (polar) “heads” of P-lipid oriented to the exterior; hydrophobic (non-polar) “tails” oriented to the interior