IB Biology 2.1

1. 2.1 Molecules to
Metabolism

2. Understandings
 Molecular biology explains living processes in terms of the chemical
substances involved.
 Carbon atoms can form four covalent bonds, allowing a diversity of
stable compounds to exist.
 Life is based on carbon compounds, including carbohydrates, lipids,
proteins, and nucleic acids.
 Metabolism is the web of all enzyme-catalyzed reactions in a cell or
organism.
 Anabolism is the synthesis of complex molecules from simpler
molecules, including the formation of macromolecules from
monomers by condensation reactions.
 Catabolism is the breakdown of complex molecules into simpler
molecules including the hydrolysis of macromolecules into
monomers.
Applications/Skills
 A: Urea as an example of a compound that
is produced by living organisms but can
be artificially synthesized.
 S: Drawing molecular diagrams of glucose,
ribose, a saturated fatty acid, and a
generalized amino acid.
 S: Identification of biomolecules such as
sugars, lipids, or amino acids from
molecular diagrams.

3. Guidance
Only the ring forms of D-ribose, alpha-D-glucose, and beta-D-glucose are expected in
drawings.
Sugars include monosaccharides and disaccharides.
Only one saturated fat is expected, and its specific name is not necessary.
The variable radical of amino acids can be shown as R. The structure of the individual R-
groups does not need to be memorized.
Students should be able to recognize from molecular diagrams the triglycerides,
phospholipids, and steroids are lipids. Drawings of steroids are not expected.
Proteins or parts of polypeptides should be recognized from molecular diagrams
amino acids linked by polypeptide bonds.

4. Carbon
 Carbon has 4 electrons in outer shell.
 Carbon can form covalent bonds with as many as 4 other atoms (elements).
 Usually with C, H, O or N.
 Example:CH4(methane)
http://i3.cpcache.com/product/1389305943/periodic_table_carbon_tile_coaster.jpg?height=460&width=460&qv
http://winking-falcon.com/engineering%20web/2manufacturing/electronics/carbon.jpg

5. Macromolecules
 Large organic molecules.
 Also called POLYMERS.
 Made up of smaller “building blocks” called MONOMERS.
 Examples:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids (DNA and RNA)
http://bio1151b.nicerweb.net/Locked/media/ch05/05_07bStarch-L.jp

6. Dehydration Synthesis
 Also called “condensation reaction”
 Anabolic
 Forms polymers by combining monomers by removing a molecule of water.
HO HO HH
H2O
HO H

7. Hydrolysis
 Separates monomers by adding a molecule of water
 Catabolic
HO H
H2O
HO HO HH

8. Metabolism
 Sum of all chemical reaction in a cell or
organism
 Involves a variety of enzymes
http://academic.pgcc.edu/~kroberts/Lecture/Chapter%205/05-
01_Metabolism_L.jpg

9. Molecule Monomer Subcategory Examples
Carbohydrates Monosaccharides Monosaccharides,
disaccharides,
polysaccharides
Glucose, fructose,
lactose, starch,
glycogen
Proteins Amino Acids Enzymes, antibodies,
some hormones
Lipids Fatty acids w/
glycerol/phosphate
group
Triglycerides,
phospholipids,
Adipose tissue,
phospholipid bilayer,
some hormones
Nucleic acids Nucleotides DNA, RNA, ATP

10. Structure of glucose and ribose
http://homebrewsake.com/wp-content/uploads/2010/04/glucose.gif http://wps.prenhall.com/wps/media/objects/3085/3159329/blb2509/25-

11. Structure of a fatty acid
http://www.charleszaremba.com/images/triglycerides2.jpg

12. Structure of an amino acid
http://www.nutrientsreview.com/wp-content/uploads/2014/10/Amino-Acid-Structure.jpg

13. Homework
Vocab
Metabolism
Catabolism
Anabolism
Hydrolysis
Condensation reaction
Vitalism
Other
 Challenge yourself #2
 Exercises 1-3
 Nature of science: Explain the idea of
vitalism. Describe why it is no longer
accepted as a scientific theory.