1

Molecular basis of life (1)

2

Chemical basis of molecular interactions

Polar and nonpolar moleculesWater

Universal solvent

O-H bonds are polarizedPartial positive and negative charges

3

Chemical basis of molecular interactions

Polar and nonpolar moleculesWater is polar blank

4

Chemical basis of molecular interactions

Polar and nonpolar molecules

Hydrocarbons are nonpolar

Properties are conferred by functional groups

A functional groupBehaves as a unit

Confers physical properties, chemical reactivity, & solubility

blank

5

Chemical basis of molecular interactions

Noncovalent bondsNot based on electron sharing

Attractive forces – readily broken and reformed

Major classesIonic bonds

Hydrogen bonds

Hydrophobic interactions and van der Waals forces

6

Chemical basis of molecular interactions

Classification of Bio-Molecules by functionMacromolecules

Four major categoriesCarbohydrates

Lipids

Proteins

Nucleic Acids

Metabolic intermediates (metabolites)

7

Classification of Bio-Molecules

CarbohydratesSimple sugars (monosaccharides)

Small chains (oligosaccharides)

Long chains (polysaccharides)

8

Classification of Bio-Molecules

CarbohydratesSimple sugars (monosaccharides)

Linking simple sugars by covalent glycosidic bonds – form :

Small chains (oligosaccharides)

Long chains (polysaccharides)

9

CarbohydratesLinking simple sugars by covalent glycosidic bonds

10

CarbohydratesGlycogen

Branched polymer containing only one type of monomer – glucose

Starch – in plants Amylose

Unbranched, helical

Amylopectin

Blank

11

Classification of Bio-Molecules

LipidsImportant categories

Fats

Steroids

phospholipids

12

Lipids

Fats – StructureGlycerol molecule + 3 fatty acids (ester bonds)

Triacylglycerol

13

Lipids

Fats – Fatty AcidsLong, unbranched hydrocarbon chains

Single terminal carboxyl group

Each end has very different structure and properties

Hydrocarbon chain is hydrophobic

Carboxyl end group is hydrophilic

Termed amphipathic

14

Lipids

Fats A Fat molecule may have the same FA or mixed FA

High energy reserve

One gram of fat contains over twice the energy of one gram of carbohydrate – lack water.

Stored in specialized cells – adipocytes

15

Lipids

Steroids Built around a characteristic four ring hydrocarbon skeleton

Cholesterol

Precursor for steroid hormones

16

Blank

Blank

Lipids

Phospholipids A diacylglycerol structure

Third hydroxyl group on the glycerol is covalently bonded to a phosphate group – then linked to a small polar group (eg. Choline)

17

Nucleic AcidsMacromolecules – long strand of monomer nucleotides

Primary function – storage and transmission of genetic information

Also structural and catalytic roles

Two typesDeoxyribonucleic acid – DNA

Ribonucleic acid - RNA

Classification of Bio-Molecules

18

Nucleic AcidsRNA – will serve as the example

19

Nucleic AcidsRNA

Each nucleotide has three partsA five-carbon sugar – ribose

A nitrogenous base (having N in the ring structure of the molecule)

A phosphate group

20

Nucleic AcidsRNA

Each nucleotide has three partsPhosphate linked to the 5’ carbon of ribose

The nitrogenous base is linked to the 1’ carbon of ribose

Blank

21

Nucleic AcidsRNA

During the assembly of the nucleic acid strand

The OH group on the 3’ carbon of ribose on one nucleotide is linked by an ester bond to the phosphate group of its neighbor

The nucleotides are connected by sugar-phosphate linkages

22

Nucleic AcidsRNA

Nitrogenous basesTwo groups

Pyrimidines – smaller – single ring

Purines – larger – two rings

23

Nucleic AcidsRNA

Nitrogenous basesTwo groups

Pyrimidines – smaller – single ring

cytosine and uracil

Purines – larger – two rings

adenine and guanine

DNAThymine replaces uracil

24

Nucleic AcidsComplementary Base Pairing

Hydrogen bonding

25

Nucleic AcidsRNA

Consist of a single continuous strand

Often folded back on itself

Blank

26

Nucleic AcidsNucleotides not involved in building nucleic acids

Adenosine triphosphate (ATP) – energy storage

Guanosine triphosphate (GTP) – signal cascade