This document summarizes key points from Dr. Ayezah Khalid's second biochemistry lecture. It discusses the essential elements and compounds needed for life, including carbon, nitrogen, oxygen, phosphorus and sulfur. It also explains important biomolecules like lipids, proteins, carbohydrates and nucleic acids - noting they are often polymers made up of repeating monomer units linked by condensation reactions. The document outlines how cells link monomers and break down polymers through dehydration synthesis and hydrolysis. It also summarizes key biomolecular structures and processes like biological membranes, nucleic acids, amino acids, enzymes and the ways life harnesses and transforms energy.

1. BIOCHEMISTRY
SECOND LECTURE
BY DR AYEZAH KHALID

2. Most abundant, essential for all organisms: C, N, O, P, S, H
Less abundant, essential for all organisms : Na, Mg, K, Ca, Cl
Trace levels, essential for all organism: Mn, Fe, Co, Cu, Zn
Trace levels, essential for some organisms: V, Cr, Mo, B, Al, Ga, Sn, Si,
As, Se, I,

3. IMPORTANT COMPOUNDS, FUNCTIONAL GROUPS

4. MANY IMPORTANT BIOMOLECULES ARE POLYMERS
lipids
membrane
phospholipid
fatty acid
proteins
protein complex
protein subunit
amino acid
carbo
cell wall
cellulose
glucose
nucleic acids
chromosome
DNA
nucleotide
monomer
polymer
supramolecular
structure

5. LIPIDS
membrane
phospholipid
fatty acid
monomer
polymer
supramolecular
structure

6. PROTEINS
Enzyme complex
protein subunit
amino acid
monomer
polymer
supramolecular
structure

7. CARBOHYDRATES
cell wall
cellulose
glucose
monomer
polymer
supramolecular
structure

8. NUCLEIC ACIDS
chromatin
DNA
nucleotide
monomer
polymer
supramolecular
structure

9. Common theme:
Monomers form polymers through
Condensations.
Polymers are broken down through
hydrolysis.

11. MOLECULAR ORGANIZATION OF A CELL

12. LINKING MONOMERS
Cells link monomers by a process called dehydration
synthesis (removing a molecule of water)
This process joins two sugar monomers
to make a double sugar

13. BREAKING DOWN POLYMERS
• Cells break down macromolecules by a process called hydrolysis (adding a
molecule of water).
Water added to split a double
sugar

14. MONOSACCHARIDES -POLYSACCHARIDES
Glucose - Cellulose
Glycosidic bonds connecting
glucose residues are in red

15. TRIGLYCERIDE
Glycerol
Fatty Acid Chains

16. STRUCTURE OF A BIOLOGICAL MEMBRANE
A lipid bilayer with associated proteins

17. STEROIDS
•The carbon skeleton of
steroids is bent to form 4
fused rings
•Cholesterol is the “base
steroid” from which your
body produces other steroids
•Estrogen & testosterone are
also steroids
Cholesterol
Testosterone
Estrogen
Synthetic Anabolic Steroids are variants of testosterone

18. NUCLEIC ACIDS
• Store hereditary information
Contain information for making all the body’s proteins
Two types exist --- DNA & RNA

19. AMINO ACIDS

20. PROTEINS AS ENZYMES
Thousands of different enzymes exist in the body
Many proteins act as biological catalysts or enzymes
Enzymes control the rate of chemical reactions by weakening bonds,
thus lowering the amount of activation energy needed for the reaction ->
Catalysator
-> No not interfere with the equilibrium of reaction
Enzymes are reusable !!!!

21. ENZYMES:
• Active site - a cleft or groove in an enzyme that binds the
substrates of a reaction
• The nature and arrangement of amino acids in the active site
make it specific for only one type of substrate.
Egg white lysozyme

22. LIFE NEEDS 3 THINGS
• (1) ENERGY, which it must know how to:
• Extract
• Transform
• Utilize

23. THE ENERGETICS OF LIFE
• Photosynthetic organisms capture sunlight energy
and use it to synthesize organic compounds
• Organic compounds provide energy for all organisms

24. GLYCOLYSIS: THE PREFERRED WAY FOR THE
FORMATION OF ATP

25. LIFE NEEDS (2) SIMPLE MOLECULES,
WHICH IT MUST KNOW HOW TO:
• Convert
• Polymerize
• Degrade

26. LIFE NEEDS (3) CHEMICAL MECHANISMS,
TO:
• Harness energy
• Drive sequential chemical reactions
• Synthesize & degrade macromolecules
• Maintain a dynamic steady state
• Self-assemble complex structures
• Replicate accurately & efficiently
• Maintain biochemical “order” vs outside

27. LIFE USES CHEMICAL COUPLING TO DRIVE
OTHERWISE UNFAVORABLE REACTIONS

28. LIFE USES ENZYMES TO SPEED UP
OTHERWISE SLOW REACTIONS

29. HOW DOES AN ENZYME DO IT,
THERMODYNAMICALLY?