1. A Study of the Molecules of Life
Biochemistry
A Study of the Molecules of Life

2. Biochemistry is based primarily on the properties of the carbon atom:
Because of its electron arrangement, carbon can form more compounds than any other element.

4. Carbon Can Form Millions of Compounds
This is a small sample of carbon-based molecules

6. Let’s play Organic or Not!!!

7. Biochemistry also takes place in a water (aqueous) environment
Water has many excellent properties as a solvent

14. Nature uses a few classes of organic molecules to build the structures found in cells
Carbohydrates
Amino acids
lipids
Nucleotides

15. A small molecule that may become chemically bonded to other monomers to form a polymer.
Large molecules consisting of large numbers of repeating units connected by covalent bonds.
Polymer:

16. Carbohydrates: Energy molecules of the cell
Carbohydrates have the general formula [CH2O]n
Glucose (right) has the formula C6H12O6
Other examples are given below:

17. Glucose is the primary fuel for cells
Glucose is broken down in several steps in the cytoplasm and mitochondria of the cell.
In these steps, energy is released that the cell can use.

18. Biological molecules can be linked together to form larger molecules
Glucose molecules (monosaccharide) can be linked together to make longer molecules (polysaccharide). In this example, cellulose is formed

19. Cellulose is the main ingredient in plant fiber

21. General structure of an amino acid
R group H N C OH O R
2.2.2
carboxyl group
amino group
(acidic)
(basic)

22. Different amino acids have different R groups
Their different properties depend on their
R groups
Hydrophobic
(‘Water-hating’) R groups
CH2 H N C OH O
phenylalanine (aromatic)
CH3 H N C OH O
alanine
Do not need to know names or structure of amino acids – interest only

23. Hydrophillic
(‘Water-loving’) R groups
CH2 H N C OH O SH
cysteine
CH2 H N C OH O
serine

24. First isolated from asparagus juice!
CH2 H N C OH O
CH2 H N C OH O
NH2
asparagine (basic)
aspartic acid (acidic)
First isolated from asparagus juice!

25. There are 20 amino acids naturally incorporated into proteins
Alanine
Arginine
Asparagine
Aspartic acid
Cysteine
Glutamic acid
Glutamine
Glycine Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Proline
Serine Threonine
Tryptophan
Tyrosine
Valine
You do NOT need to know their names!

26. These are the essential amino acids:
Humans can synthesize some amino acids by altering other amino acids, however…
…some amino acids cannot be synthesized and are therefore needed in the diet.
These are the essential amino acids:
Arginine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Interest only but see Option A 2.8

27. Formation of a dipeptide: carboxyl group of one amino acid reacts with amino group of second amino acid H N C OH O R2 R1
water molecule formed H N C O R1 OH R2
H2O
2.2.6
a dipeptide
peptide linkage

28. 2 amino acids  dipeptide + water
Formation of a dipeptide produces a molecule of water, therefore… H N C OH O R1 R2
H2O
…this is a condensation reaction H N C O R1 OH R2
Part of 2.2.5
2 amino acids  dipeptide + water

29. dipeptide + water  2 amino acids
Splitting a dipeptide to form two amino acids consumes one molecule of water, therefore… H N C O R1 OH R2
H2O H N C OH O R1 R2
…this is a hydrolysis reaction
Part of 2.2.5
dipeptide + water  2 amino acids

30. Three amino acids linked together
Tripeptide:
Three amino acids linked together
Oligopeptide:
A short chain of a few amino acids
Polypeptide:
A chain of many amino acids
A protein may consist of one or more polypeptide chains
Structure of hemoglobin – a protein consisting of four polypeptides

31. Proteins are tremendously complex structures that perform many functions in cells
The protein shown to the right is called myosin. It is one of many proteins that work to make your muscles contract

32. Some proteins act as chemical signals (hormones) in the body.
Insulin is made by cells of the pancreas. When it is released into the blood, it signals other tissues (e.g. muscle) to take glucose from the blood after a meal.

33. Proteins called enzymes act to speed up chemical reactions in cells
The diagram shows a model of trypsin, an enzyme that speeds up the breakdown of proteins during digestion.

34. Many proteins are important components of cellular structures
Membrane channel proteins allow ions to flow in and out of cells.

35. Proteins can even make the world’s smallest motors
This is a model of the flagellum in a bacterium. At the basal body is a small motor that spins the hook and thus moves the flagellum (made of flagelin) through water.
This motor is no bigger than 50 nanometers!

36.  Lipids: a large and varied group of organic compounds.
 Lipids include:
Triglycerides
Phospholipids
Waxes
Cholesterol and Steroids
Lipids are all non-polar and do not dissolve in water, due
to this. They are INSOLUBLE.

37.  Triglycerides are one of the most common types of lipids
 Triglycerides consist of one molecule of glycerol bonded to three fatty acid molecules
 Each fatty acid is linked to the glycerol molecule by an ester bond C H OH
Glycerol
Hydroxyl groups

38. Carboxyl group
Fatty Acids:
General Formula:
CH3
(CH2)n C O OH
CH3 H C O OH
CH2

39. H C O OH
Can be drawn as: C O OH

40. This is a condensation reaction
Forming a monoglyceride: C O OH C H OH
Hydroxyl group and carboxyl group react
Ester bond C H OH O
+ H2O
This is a condensation reaction

41. A triglyceride: C H O
Glycerol
Fatty acid
Can be drawn as:
Ester bond

42. This is a hydrolysis reaction
To split these ester bonds and separate a fatty acid from glycerol we need to add a molecule of water C H OH O C H OH
+ H2O C O OH
This is a hydrolysis reaction

43. Uses of Lipids in Living Things
1. Long-term energy stores
Human Adipose Tissue
Plant Oils

44. 2. Buoyancy for marine. animals: lipids are less. dense than water so
2. Buoyancy for marine animals: lipids are less dense than water so help animals float
3. Insulation: a layer of fat beneath the skin cuts down heat loss

45. Phospholipids are modified so that a phosphate group (PO4-) is added to one of the fatty acids.
Phospholipids are important components of cell membranes (below).

46. Cholesterol and steroids are also part of the lipid group
Testosterone is an important hormone.
Cortisone and vitamin D play important roles in regulating mineral balances in blood.
Cholesterol is a part of our diet and is used as a starting point to make the other molecules.

47. Lipids are also a useful energy source for the cell.
The products of fatty acid breakdown can produce energy for the cell.
In fact, virtually all biological molecules can produce energy if needed.
Lipids produce the most energy per unit mass.
Energy

49. Homework:
Compare the relative advantages and disadvantages to an organism of using carbohydrates vs. lipids as energy stores.
To be handed in on a separate sheet of paper on Monday (Along with the review packet you’re about to get )