1. TOPIC 3.2 MOLECULES OF CELLS

2. ORGANIC and INORGANIC MOLECULES
3.2.1
ORGANIC MOLECULES: molecules containing C and H in their structure
INORGANIC MOLECULES : molecules which do not have C in its structure.

4. An organic compound has unique properties that depend upon the
A few chemical groups are key to the functioning of biological molecules
An organic compound has unique properties that depend upon the
size and shape of the molecule and
groups of atoms (functional groups) attached to it.
A functional group affects a biological molecule’s function in a characteristic way.
Compounds containing functional groups are hydrophilic (water-loving).
Student Misconceptions and Concerns
General biology students might not have previously taken a chemistry course. The concept of molecular building blocks that cannot be seen can be abstract and difficult to comprehend for such students. Concrete examples from our diets and good images will increase comprehension.
Teaching Tips
A drill with interchangeable drill bits is a nice analogy to carbon skeletons with different functional groups. The analogy relates the role of different functions to different structures.
© 2012 Pearson Education, Inc. 4

5. The functional groups are
A few chemical groups are key to the functioning of biological molecules
The functional groups are
hydroxyl group—consists of a hydrogen bonded to an oxygen,
carbonyl group—a carbon linked by a double bond to an oxygen atom,
carboxyl group—consists of a carbon double-bonded to both an oxygen and a hydroxyl group,
amino group—composed of a nitrogen bonded to two hydrogen atoms and the carbon skeleton, and
phosphate group—consists of a phosphorus atom bonded to four oxygen atoms.
Student Misconceptions and Concerns
General biology students might not have previously taken a chemistry course. The concept of molecular building blocks that cannot be seen can be abstract and difficult to comprehend for such students. Concrete examples from our diets and good images will increase comprehension.
Teaching Tips
A drill with interchangeable drill bits is a nice analogy to carbon skeletons with different functional groups. The analogy relates the role of different functions to different structures.
© 2012 Pearson Education, Inc. 5

6. Table 3.2 Important chemical groups of organic compounds6

7. A few chemical groups are key to the functioning of biological molecules
An example of similar compounds that differ only in functional groups is sex hormones.
Male and female sex hormones differ only in functional groups.
The differences cause varied molecular actions.
The result is distinguishable features of males and females.
Student Misconceptions and Concerns
General biology students might not have previously taken a chemistry course. The concept of molecular building blocks that cannot be seen can be abstract and difficult to comprehend for such students. Concrete examples from our diets and good images will increase comprehension.
Teaching Tips
A drill with interchangeable drill bits is a nice analogy to carbon skeletons with different functional groups. The analogy relates the role of different functions to different structures.
© 2012 Pearson Education, Inc. 7

9. ORGANIC MOLECULES 3.2.2
Monomer: smallest unit of an organic molecules e.g: glucose
Dimer: two monomers
Polymer: many monomers are linked to each other to form macromolecules.
How are they linked to each other? condensation
How are they broken down? hydrolysis

10. CONDENSATION 3.2.5

11. HYDROLYSIS 3.2.5

12. 3.2.2

13. CARBOHYDRATES 3.2.3
FUNCTIONS: 1- main energy source for cells 2- structural elements STRUCTURE: consist of C, H,O Monosaccharide, Disaccharides, Polysaccharides

14. 3.2.3. Monosaccharides Hexoses (6C sugars) Glucose Fructose Galactose
Pentoses (5C sugars)
Ribose
Deoxyribose
They are soluble in water. Why?

16. 3.2.3. Disaccharides Glucose + Glucose Maltose
Fructose + Glucose Sucrose
Galactose + Glucose Lactose
They are less soluble than monosaccharides.

17. Polysaccharides 3.2.4 Starch Cellulose
Glucose + Glucose + Glucose Glycogen
Cellulose
Chitin is a N containing polysaccharide which is found in the exoskeleton of insects and cell wall of fungi.
They are not soluble or slightly soluble.

18. 3.2.4

19. Polymerization by dehydration synthesis
monomers
polymer +
ATP H2O H2O H2O
monosaccharide, amino acid or nucleotide
polysaccharide, protein or polynucleotide
enzyme

20. Polymerization Happens by dehydration synthesis
Monomers are joined by covalent bonds to form polymers
3 different covalent bonds can be formed:
Glycosidic bond between monosaccharides
Peptide bond between amino acids
Phosphodiester bonds between nucleotides

21. Polymerization Enzymes are used ATP is required
1 H2O molecule is released for each bond made between monomers

22. Depolymerization by hydrolysis
monomers
H2O H2O H2O
monosaccharide, amino acid or nucleotide
polysaccharide, protein or polynucleotide
enzyme

23. Depolymerization Happens by hydrolysis
Polymers are broken down into monemers by adding a water.
Energy is not used
Enzymes are required.
Example: digestion

24. LIPIDS 3.2.6 Do all living things have lipids?
Which elements do lipids contain?
Are lipids hydrophilic?

25. What are the functions of lipids? 3.2.6
Storage of energy
Structural elements (cell membrane, hormones, myelin sheat)
Thermal insulation. How?

29. Fatty acids Essential fatty acids

31. Saturated fats vs. Unsaturated fats

32. Triglyceride (oil or fat)
3.2.6
Triglyceride (oil or fat)
Natural fats, found in the fat tissue of animals, seed and fruit of plants.
Phospholipids
Main component of the cell membrane
Steroids
Cholesterol, sex hormones
Wax
Water proof material around fruits, leaves.

34. Triglycerides

35. Cholesterol Essential component of animal cell membranes
Precursor for the synthesis of vitamin D and steroid hormones such as testosterone and estrogen
Important for the metabolism of fat soluble vitamins (A, D, E, K)

37. Phospholipids