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

Saturated fats vs.

Unsaturated fats

• 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