TOPIC 3.2 MOLECULES 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.

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

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

Table 3.2 Important chemical groups of organic compounds 6

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

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

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 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.

3.2.4

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

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

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

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

Depolymerization Happens by hydrolysis Polymers are broken down into monemers by adding a water. Energy is not used 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 acids Essential fatty acids

Saturated fats vs. Unsaturated fats

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.

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