1. CHE 214: Biochemistry
Lecture one
TODAYS TOPICS
•INTRODUCTION AND COURSE OUTLINE
•CARBOHYDRATES
•LIPIDS
Lecturer: Dr. G. Kattam Maiyoh
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2. CHE 214: BIOCHEMISTRY
Contact information
Dr. Geoffrey Kattam Maiyoh
E-mail: maiyoh07@yahoo.com / jeffkattam@gmail.com Tel: 0713-592879
Website: http://MAIYOH.1faculty.com
Recommended Textbooks/ Lecture Notes
•L. Stryer, Biochemistry
•Lehninger, Principles of Biochemistry
•Any other textbook of Biochemistry
•Power point lecture notes will be available after class (Class
representatives to collect on flash discs).
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3. Examination
–CAT s – 20%
–Practical – 10%
–Final Exam – 70%
–Everyone is required to be present during CATs and Exams
•Examination / CATs Format
•CAT Questions – Both CATs will comprise 30 questions each. There will be 3
sections in each CAT paper (Multiple choice, Structured i.e. “Filling in the blank spaces”
and True/False sections)
• Examination Questions – All Exam questions will be in essay form
•Attendance
–Exams will mostly be based on the material presented during
classes.
–It is in your best interest to attend each lecture.
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4. TOPICS Title
DNA
1. Biological Molecules: Structure, Chemistry and Function of
Carbohydrates and Lipids
2. Biological Molecules: Structure, Chemistry and Function of
Proteins and Nucleic acids
3. Bioenergetics: Pathways of Glucose, Fat and Amino acid
metabolism
CAT ONE
4. Biomembrane Chemistry
5. Introduction to Enzymology
6. Biochemistry Techniques: Preparation of buffers and PH
measurement
7. Biochemistry Techniques: Chromatography, Column, Paper,
Gas-Liquid Chromatography
PROTEIN CAT TWO
8. Biochemistry Techniques: Electrophoresis, Precipitation,
Colorimetry, Spectrophotometry, Flame Photometry
EXAMINATIONS
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5. Cells as chemical reactors
• Living organisms obey the laws of chemistry and
physics
– Can think of cells as complex chemical reactors in
which many different chemical reactions are
proceeding at the same time
• All cells are more similar than different if looked
at on the inside!
– Strip away the exterior and we see that all cells need
to accomplish similar tasks and in a broad sense they
use the same mechanisms (chemical reactions)
– This MAY reflects a singular origin of all living things!
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6. LUCA (Last Universal Common Ancestor)
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7. Some key similarities among all types of cells
• All cells use nucleic acids (DNA) to store
information
– RNA viruses, but not true cells
(incapable of autonomous replication)
– All cells use nucleic acids (RNA) to access
stored information
• All cells use proteins as catalysts
(enzymes) for chemical reactions
– A few examples of RNA based enzymes, which
may reflect primordial use of RNA
• All cells use lipids for membrane
components
– Different types of lipids in different types of
cells
• All cells use carbohydrates for cell walls (if
present), recognition, and energy
generation
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8. • Biologically important macromolecules are
“polymers” of smaller subunits
• Created through condensation reactions
Macromolecule Subunit
Carbohydrates : simple sugars
Lipids : CH2 units
Proteins : amino acids
Nucleic acids : nucleotides (Base,
Sugar and Phosahate)
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9. Where do the subunits come from?
• All cells need a source of the atomic components of the
subunits
– (C, O, H, N, P, and a few other trace elements )
There are several possibilities to acquire them. They
include;
i. Some cells can synthesize all of the subunits given these
atomic components and an energy source
ii. Some cells can obtain these subunits from external sources
iii. Some cells can convert other compounds into these
subunits
• We will discuss further in section on Bioenergetics
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10. Carbohydrates
• All have general formula CnH2nOn (hydrates
(H2O) of carbon)
• A variety of functions in the cell
– Large cross-linked carbohydrates make up the
rigid cell wall of plants, bacteria, and insects
– In animal cells, carbohydrates on the exterior
surface of the cell serve a recognition and
identification function
– A central function is energy storage and energy
production !
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11. Carbohydrates
– Cell structure:
– Cellulose, LPS, chitin
Chitin in exoskeleton
Cellulose in plant cell walls Lipopolysaccharides (LPS)
in bacterial cell wall
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12. Carbohydrate Structure
Monosaccharides may also form part of other biologically important molecules
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13. Carbohydrate Structure
• Complex carbohydrates are built from simple sugars
– Most often five (pentose) or six (hexose) carbon
sugars
– Numerous –OH (hydroxyl) groups can form many
types of “cross links”
– Can result in very complex and highly cross linked
structures ( cellulose, chitin, starch, etc.)
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14. Carbohydrate Structure
A Few Examples
• Triose (3 carbon)
– Glyceraldehyde
• Pentose (5 carbon)
– Ribose
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15. Carbohydrate Structure
Example of two hexoses
– Glucose Galactose
– What’s the difference? Both are C6H12O6
• They are isomers of one another!
• Same molecular formula, but different structure (3D-
shape).
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16. Carbohydrate Structure
• Monosacharides can be joined to one another to form
disaccharides, trisaccharides, ……..polysaccharides
– Saccharide is a term derived from the Latin for sugar (origin = "sweet sand")
• Carbohydrates classified according to the number of
saccharide units they contain.
– A monosaccharide contains a single carbohydrate, over
200 different monosaccharides are known.
– A disaccharide gives two carbohydrate units on hydrolysis.
– An oligosaccharide gives a "few" carbohydrate units on
hydrolysis, usually 3 to 10.
– A polysaccharide gives many carbohydrates on hydrolysis,
examples are starch and cellulose.
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17. Carbohydrate Structure
Pentoses and hexoses are capable of forming ring (cyclic) structures.
An equilibrium exists between the ring and open form.
Linear form Ring (cyclic) form
Fructose
Glucose
The carbonyl group reacts with the –OH group on the second to the last carbon
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18. Condensation reaction
Two simple sugars can polymerize to form a disaccharide. For example, galactose
reacts with glucose to form lactose, which is the sugar found in milk.
Lactose on the other hand can be hydrolyzed to form the two monosaccharodes
the enzyme by lactase
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19. Glycosidic bond
•The type of chemical linkage between the monosaccharide
units of disaccharides, oligosaccharides, and polysaccharides,
which is formed by the removal of a molecule of water (i.e. a
condensation reaction).
•The bond is normally formed between the carbon-1 on one
sugar and the carbon-4 on the other.
•An α-glycosidic bond is formed when the –OH group on
carbon-1 is below the plane of the glucose ring and a β-
glycosidic bond is formed when it is above the plane.
•Cellulose is formed of glucose molecules linked by 1-4 β-
glycosidic bonds, whereas starch is composed of 1-4 α-
glycosidic bonds.
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20. Carbohydrate Structure
They are a special type of isomers of one another. Called anomers
α-isomer β-isomer
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21. Two common small carbohydrates
Glyceraldehyde Ribose
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22. Complex Carbohydrates
• Cellulose
Most abundant carbohydrate on the planet!
– Component of plant cell walls
– Indigestible by animals
• β 1-4 bonds
• Starch
– Energy storage molecule in plants
– Can be digested by animals
• α 1-4 bonds
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24. Complex Carbohydrates
• Glycogen
– Branched chain polymer of glucose
– Animal energy reserve
– Found primarily in liver and muscle
• α 1-4 & α 1-6 bonds
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25. • Glycogen
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26. Cellulose
• Cellulose is a linear polysaccharide
in which some 1500 glucose rings
link together. It is the chief
constituent of cell walls in plants.
• Human digestion cannot break
down cellulose for use as a food,
animals such as cattle and termites
rely on the energy content of
cellulose.
• They have protozoa and bacteria
with the necessary enzymes in their
digestive systems.
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27. Starches
• Starches are carbohydrates in which 300 to
1000 glucose units join together. It is a
polysaccharide used to store energy for
later use.
• Starch forms in grains with an insoluble
outer layer which remain in the cell where
it is stored until the energy is needed. Then
it can be broken down into soluble glucose
units.
• Starches are smaller than cellulose units,
and can be more readily used for energy. In
animals, the equivalent of starch is
glycogen, which can be stored in the
muscles or in the liver for later use.
Has α-1,6 bonds glycosidic linkages
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28. polysaccharides can be linked to other
molecules to form glyco-proteins and glyco-lipids
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29. Glycoproteins
Some examples
• Polysaccharide component of antibodies has major effect
on antibody function
• Polysaccharides attached to proteins on surface of red
blood cells (RBC) determine blood type (A,B,O) .
 See next slide
– Polysaccharides are attached to proteins in the Golgi apparatus
through a process of post-translational modification
• Different types of cells do different post-tranlational modifications
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30. Glycoproteins
Mediate Cell
Recognition
Your ABO bloodtype is
determined by what sugars
you have in a particular
oligosaccharide side chain
on one of the proteins that
lies on the surface of your
red blood cells
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31. Other Functions Of Glycoproteins
Contact Inhibition
Cells stop growing when they contact neighbors
This function is disrupted in some cancers
Protein Turnover
Many glycoproteins have sialic acid residues at the end of the
carbohydrate chain. Loss of these sialic acid residues indicates
the protein is old and ready to be turned over.
Antifreeze
Some fish that live in cold water produce glycoproteins that lower
the freezing point of their body’s water, thereby enabling them
to survive the cold water
Hiding Viruses
Some viruses can modify their cell surface proteins to mimic the
native glycoproteins, thereby hiding from the host’s immune system
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32. Glycolipids
• Polysaccharides can be attached to lipid molecules
•An outer-membrane
constituent of gram
negative bacteria, LPS,
which includes O-antigen,
a core polysaccharide and
a Lipid A, coats the cell
surface and works to
exclude large hydrophobic
compounds such as bile
salts and antibiotics from
invading the cell.
•O-antigen are long hydrophilic carbohydrate chains (up to 50 sugars long) that
extend out from the outer membrane
•While Lipid A (and fatty acids) anchors the LPS to the outer membrane.
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33. Lipids
• Lipids include the following;
– Fatty acids (Polymers of CH2 units)
– Glycerol
– Triglycerides
– Other subunits (phosphate, choline, etc) may be attached
to yield “phospholipids”
• Charged phosphate groups will create a polar molecule with a
hydrophobic (nonpolar) end and a hydrophillic (polar) end
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35. Lipids
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36. Phospholipids
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37. Function
– Energy Storage
• Triglycerides
– Cell membranes and cell compartments
– Bi-layer structure
• Outer or plasma membrane
• Nuclear membrane
• Internal structures
– ER, Golgi, Vesicles, etc.
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38. Phospholipid bilayer
Hydrophillic heads
Hydrophobic tails
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39. Steroids
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