Biology 2121Chapter 2

Biochemistry Biochemistry 1. Introduction

Biochemistry

2. Macromolecules contain carbon Valance = 4 Bonds with oxygen, hydrogen and

nitrogen

Carbohydrates

1. General characteristicsSoluble in water (decreases with size)Sizes – small single units to larger compounds

2. Function (s)Energy – 4 kcal/gCell membrane – cell to cell recognition

3. Structure Monomer – monosaccharidePolymer – polysaccharide

Carbohydrates

1. MonosaccharidesC6H12O6 - isomers

2. Disaccharides Formed by

dehydrationSplit-up by

hydrolysis

3. PolysaccharidesStarch, Glycogen

1.Glycogen – STORED IN THE LIVER

2.Starches – plants

3.Cellulose - roughage

1.Glycogen – STORED IN THE LIVER

2.Starches – plants

3.Cellulose - roughage

1. General Characteristics Insoluble in water – soluble in other nonpolar

substances (alcohol) Non-polar structure

2. Function(s) Energy – 9 kcal/g Cell membrane, steroids, fat-soluble vitamins

3. Structure Most – fatty acid tail (H-C chain) that is non-

polar

Lipids

STRUCTURE OF A TRIGLYCERIDE

1.Formation – dehydration synthesis

2.Single bonding between carbons – ‘saturated’

• Long FA chains – solid at room temperature

3.CH2 – fatty acid tails

1. Unsaturated and Polyunsaturated TriglyceridesDouble bonding between the carbonsChains ‘bend’ or form kinks

Plant lipids; olive, corn, safflower oil Chains are shorter than saturated fatty acid

triglycerides

PHOSPHOLIPID

1.BILAYER OF A PLASMA MEMBRANE

2.Two FA tails; glycerol; phosphate (polar)

3.Amphipathic – polar and non-polar nature

CHOLESTEROL IS CLASSIFIED AS A STEROL – LIPID. MADE UP OF ‘FUSED’ CARBON RINGS AND SIDE CHAINS OF MOLECULES

A ‘PRECURSOR’ TO OTHER STEROIDS – TESTOSTERONE, VITAMIN D

Side-chains made each steroid different

Proteins1. General Characteristics

Basic structural component of the body C, H, O and Nitrogen!

2. Function(s) Cell functions – transport of material across cell

membrane; hemoglobin; muscle contractile protein Biological Catalysts - enzymes

3. Structure Monomer: amino acids

Peptide bonding via dehydration Polymer: Polypeptide

Formation of a protein

1.Primary Structure• As amino acid form straight

chains via peptide bonding• Occurs during ‘protein

synthesis’ - ribosomes of the cell

2.Secondary Structure• Twist or bends after primary

formation • Hydrogen bonds stabilize

• Between NH and CO

3.Two forms• Beta and alpha-helix

A polypeptide chain may contain both secondary structures!

Other Structures

1.Secondary structures fold up on themselves.

2.Adjacent amino acids interact or form covalent and hydrogen bond. Forms a 3-D Tertiary structure

• Enzymes

3.If two or more tertiary structures (polypeptides) interact – quaternary structure

• Hemoglobin (blood) or myoglobin (muscles)

Proteins – Structural Types

Fiberous – only secondary; insoluble and stable; collagen; keratin

Globular – tertiary structure; soluble; enzymes, antibodies

Enzymes1. What are enzymes?

Biological catalystsSpecific tertiary structure

2. Substrate and active sites

3. Function(s)Drive chemical reactions in cells!

4. How enzymes work (Lowering of energy activation)Activation Energy (animation)

1. “HOW ENZYMES WORK” – ANIMATION (Chapter 12 – Alternate)

2. Biochemical pathways (enzyme mediated)

3. Feedback in Biochemical Pathways

Enzyme Denaturation

1.When enzymes (proteins) stop working.

2.Why?

• Temperature; pH changes

• Bonds and interactions between amino acids fail – unravels and loses 3D shape

Animation1.Denaturation

Activation Energy and Enzymes Activation Energy and Enzymes

Nucleic Acids1. General Characteristics

C, H, O, N and Phosphorus

2. Function(s) DNA – genes – heredity RNA – important in production of proteins

3. Structure Monomer: nucleotide (phosphate - 5 carbon

sugar – nitrogen base Polymer: Deoxyribonucleic Acid and

Ribonucleic Acid

Nucleotides and DNA

1. Phosphates bonded to 5–C deoxyribose sugar via covalent bonding

2. Sugar bonded to nitrogen base (green and yellow) via covalent bonding

3. Bases bonded via hydrogen bonding (weak; unzips)

4. Base pairing rules: A-T; G-C

• Hydrogen bonding between bases

• Base pairing

• Sugar-Phosphate backbone

• Double Helix

ATP – Adenosine Triphosphate 1. Glucose is the fuel that

powers the cell.

2. As glucose is oxidized (anabolic), ATP is built up in the process of cellular respiration – mitochondria of the cell

3. Energy is stored in the bonds of ATP

4. Contains ribose sugar (RNA) and adenine base.

5. Three phosphates – two have unstable bonds and negative charges – repel

6. Bonds are broken – energy released – drives cellular work