Biochemistry

BIO 3 b, cOBJECTIVE:• TSW investigate and understand the

chemical and biochemical principles essential for life.

Key concepts include-• b) the structure and function of

macromolecules• c) the nature of enzymes.

• Most life processes are a series of chemical reactions influenced by environmental and genetic factors.

Metabolism• the sum of all biochemical

processes

2 Metabolic Processes

• Anabolism- the building up of complex molecules

•Catabolism- the breaking down of complex molecules

• Most cells function best within a narrow range of temperature and pH.

• At very low temperatures, reaction rates are too slow.

• High temperatures or extremes of pH can irreversibly change the structure of proteins and alter their function.

–The main components of a living cell are: • Carbon• Hydrogen• Nitrogen• Oxygen

-Phosphorus-Sulfur

• Inside every cell is a concentrated mixture of thousands of different macromolecules forming a variety of specialized structures that carry out cell functions, such as:– energy production– transport– waste disposal– synthesis (creation) of new molecules– storage of genetic material.

Organic Compounds

• Compounds that contain CARBON are called organic.

• Macromolecules are large organic molecules.

Carbon (C)• Carbon has 4 electrons in outer shell

• Carbon can form covalent bonds with as many as 4 other atoms (elements)

• Usually with H, O, N, or C

• Example: C6H12O6 (sugar)

Macromolecules• Large organic molecules.• Also called POLYMERS.• Made up of smaller “building blocks” called

MONOMERS.• Examples:

1. Carbohydrates2. Lipids3. Proteins4. Nucleic acids (DNA and RNA)

1. Carbohydrates• Small sugar molecules to large sugar

molecules.

• Examples:A. monosaccharideB. disaccharideC. polysaccharide

1. CarbohydratesA.monosaccharide: one sugar unit• Examples: glucose (C6H12O6 blood sugar)

deoxyriboseribosegalactose (milk sugar)fructose (honey)

glucose

B. disaccharide: two sugar unit• Example: sucrose = glucose + fructose

fructoseglucose

C. polysaccharide: many sugar units• Examples: starch (bread, potatoes)

glycogen (beef muscle)

cellulose (lettuce, corn)

chitin (exoskeletons)glucoseglucose

glucoseglucose

glucoseglucose

glucoseglucose

cellulose

• The primary functions of carbohydrate macromolecules are to:– provide and store energy.

2. Lipids• General term for compounds which are not

soluble in water.• Lipids are soluble in hydrophobic

solvents.• Remember: “stores the most energy”

2. Lipids• Examples: 1. Fats

2. Phospholipids3. Oils4. Waxes5. Steroid hormones6. Triglycerides

• 5 functions of lipids:1. Long term energy storage (fat)2. Protection against heat loss (insulation)3. Protection against water loss & germs (oils & waxes)4. Chemical messengers

(hormones & steroids)5. Major component of membranes

(phospholipids)

• Triglycerides: composed of 1 glycerol and 3 fatty acids.

HH-C----O

H-C----O

H-C----O

H

glycerol

OC-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

=

fatty acids

OC-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

=

OC-CH2-CH2-CH2-CH =CH-CH

2 -CH2 -CH

2 -CH2 -CH

3

=

• There are two kinds of fatty acids you may see on food labels:1. Saturated fatty acids: no double bonds (bad)2. Unsaturated fatty acids: double bonds (good)

OC-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

=

saturatedOC-CH2-CH2-CH2-CH =CH-CH

2 -CH2 -CH

2 -CH2 -CH

3

=

unsaturated

3. Proteins (Polypeptides)• Amino acids (the building blocks of

protein)• 2 kinds of amino acids - essential & non-essential amino acids

- Essential amino acids cannot be synthesized by our body & need to be obtained through our diet

• 7 functions of proteins:

1. Storage: albumin (egg white)2. Transport: hemoglobin3. Regulatory: hormones4. Movement: muscles5. Structural: membranes, hair, nails6. Enzymes: cellular reactions7. Defense: antibodies

• A protein’s structure depends on its specific job

• The sequence of amino acids and the shape of the chain are a consequence of attractions between the chain’s parts.

• Four levels of protein structure:

A. Primary Structure (1°)B. Secondary Structure (2°)C. Tertiary Structure (3°)D. Quaternary Structure (4°)

A. Primary Structure (1°)• Amino acids bonded together by

peptide bonds.

aa1 aa2 aa3 aa4 aa5 aa6

Peptide Bonds

Amino Acids (aa)

B. Secondary Structure (2°)

• 3-dimensional folding arrangement of a primary structure into coils and pleats held together by hydrogen bonds.

B. Secondary Structure (2°)Two examples:

Alpha Helix

Beta Pleated Sheet

Hydrogen Bonds

Alpha Helix

Beta Pleated Sheets

C. Tertiary Structure (3°)• Secondary structures bend and fold into

a more complex 3-D arrangement.

• Called a “subunit”.

C. Tertiary Structure (3°)

Alpha Helix

Beta Pleated Sheet

D. Quaternary Structure (4°)• Composed of 2 or more “subunits”.• Example: enzymes (hemoglobin)

3° subunits

Subunits

Enzymes: Special Proteins

4. Nucleic acids• Nucleic acids (DNA and RNA) control cell

activities by controlling protein synthesis

4. Nucleic acids• Two types:

1. deoxyribonucleic acid (DNA-double helix)2. ribonucleic acid (RNA-single strand)

• Nucleic acidsare composed of long chains of

nucleotides

4. Nucleic acids• Nucleotides:

phosphate groupsugar (5-carbon)nitrogenous bases

adenine (A)thymine (T) - uracil (U)

RNAcytosine (C)guanine (G)

Nucleotide

OO=P-O O

Phosphate Group

NNitrogenous base (A, G, C, or T)

CH2

O

C1C4

C3 C2

5

Sugar(deoxyribose)

DNA - double helix

P

P

P

O

O

O

1

23

4

5

5

3

3

5

P

P

PO

O

O

1

2 3

4

5

5

3

5

3

G C

T A