TOPIC 3.2MOLECULES OF CELLS
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.
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).
© 2012 Pearson Education, Inc.
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.
© 2012 Pearson Education, Inc.
Table 3.2
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.
© 2012 Pearson Education, Inc.
ORGANIC MOLECULES3.2.2
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
CONDENSATION 3.2.5
HYDROLYSIS 3.2.5
3.2.2
CARBOHYDRATES 3.2.3
FUNCTIONS:
1- main energy source for cells
2- structural elements
STRUCTURE: consist of C, H,O
Monosaccharide, Disaccharides, Polysaccharides
3.2.3. Monosaccharides
Hexoses (6C sugars)
Glucose
Fructose
Galactose
Pentoses (5C sugars)
Ribose
Deoxyribose
They are soluble in water. Why?
3.2.3. Disaccharides
Glucose + Glucose Maltose
Fructose + Glucose Sucrose
Galactose + Glucose Lactose
They are less soluble than monosaccharides.
Polysaccharides 3.2.4
Starch
Glucose + Glucose + Glucose +..... Glycogen
CelluloseChitin 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.
3.2.4
Polymerization by dehydration synthesis
+ + +
+
ATP H2O H2O H2O
monosaccharide, amino acid or nucleotide
polysaccharide, protein or polynucleotide
enzyme
monomers polymer
Polymerization
1. Happens by dehydration synthesis
2. 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
Polymerization
4. Enzymes are used
5. ATP is required
6. 1 H2O molecule is released for each bond made between monomers
+ + +
H2O H2O H2O
monosaccharide, amino acid or nucleotide
polysaccharide, protein or polynucleotide
Depolymerization by hydrolysis
enzyme
monomerspolymer
Depolymerization
1. Happens by hydrolysis
2. Polymers are broken down into monemers by adding a water.
3. Energy is not used
4. Enzymes are required.
Example: digestion
LIPIDS 3.2.6
• Do all living things have lipids?
• Which elements do lipids contain?
• Are lipids hydrophilic?
What are the functions of lipids? 3.2.6
• Storage of energy
• Structural elements (cell membrane, hormones, myelin sheat)
• Thermal insulation. How?
Fatty acidsEssential fatty acids
• 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
• WaxWater proof material around fruits, leaves.
Triglycerides
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)
Phospholipids