CHAPTER 1_functional Group

8/6/2019 CHAPTER 1_functional Group

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MACROMOLECULES

1

By: Hamizah Othman



TOPIC OUTLINES1.1 Functional group

1.2 Water

1.3 Amino acid, peptides and protein1.4 Structure and functions of carbohydrate

1.5 Structure and functions of lipid

1.6 Structure and functions of nucleic acids

2Prepared by: Hamizah Othman



OVERVIEW� Although cells are 7095% water, the rest consists

mostly of carbon-based compounds

� Carbon is unparalleled in its ability to form large,complex, and diverse molecules

� Proteins, DNA, carbohydrates, and other moleculesthat distinguish living matter are all composed of

carbon compounds




Hydrocarbonsy Hydrocarbons are organic molecules consisting of

only carbon and hydrogen

y Many organic molecules, such as fats, havehydrocarbon components

y Hydrocarbons can undergo reactions that release alarge amount of energy

y Most organic compounds contain hydrogen atoms inaddition to carbon atoms




Isomers

y Isomers are compounds with the same molecularformula but different structures and properties:y Structural isomers have different covalent arrangements

of their atoms

y Geometric isomers have the same covalent arrangementsbut differ in spatial arrangements

y Enantiomers are isomers that are mirror images of each

other




(a) Structural isomers

2-meth yl butanePentane




(b) Geometric isomers

cis isomer: The tw o Xs areon the same side.

trans isomer: The tw o Xs areon opposite sides.




(c) Enantiomers

L isomer D isomer

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Prepared by: Hamizah Othman



1.1. FUNCTIONAL GROUPSy Functional groups are the components of organic

molecules that are most commonly involved in

chemical reactionsy The number and arrangement of functional groups

give each molecule its unique properties

y The characteristics of an organic molecule can be

changed dramatically by replacing one of the hydrogen with a f unctional group

y Compounds containing functional groups areh ydrophilic (water-loving) except for methyl group.




y The seven functional groups that are most important in thechemistry of life:

y Hydroxyl group

y Carbonyl group

y Carboxyl group

y Amino group

y Sulfhydryl group

y Phosphate group

y Methyl group




1) Hydroxyl Group

y Consist of a h ydrogen atom bonded to an oxygenatom, which in turns is bonded to the carbon skeleton.

yExample is ethanol.

(R - OH)




y Functional Properties:

- is polar as a result of the electrons spending more

time near electronegative oxygen atom.- can form hydrogen bonds with water molecules,helping dissolve organic compounds such as sugars

- Molecules with this functional group form alcohols

and components of sugars- compounds with hydroxyl group are called alcohols(specific name usually end in ol )




2) Carbonyl Group

y Consist of a carbon atom that linked by a d oubl e bond to an oxygen atom.

y T wo types:

a. Ketone: if the carbonyl group is withinthe the chain

b. Aldeh yde: if the carbonyl group is at theend of the carbon skeleton

(R -C= O)




y Example: Acetone (ketone)

Propanal (aldehyde)




y

Functional Properties:

- is polar as a result of the electronegative oxygen

- is h ydrophilic (having affinity to water) thus its

increase solubility of organic compound in water- ketone and aldehyde may be structural isomers with

different properties

- these two groups (ketone and aldehyde) are also

found in sugars ;giving rise to two major groups of sugars (aldose and ketose)




3) Carboxyl Group

y Consists of a carbon d oubl e-bonded to an oxygen andalso bonded to a h ydroxyl group (OH)

yExample is acetic acid

(R - COOH)





- strongly polar as generally found in ionizes f orm(giving up H+) with a charge of 1-

- compounds with carboxyl group are calledcarboxylic acid

- has acidic properties (source of hydrogen ions/donates H+)




4) Amino Group

y Composed of a nitrogen bonded to two h ydrogenatoms and the carbon skeleton.

y

Example: Glycine (amino acid)

(R -NH2)





- strongly polar and usually act as a base ( pick upH+ from surrounding solution)

- compounds with amino group are called amines

- ionized with a charge of 1+, under cellular conditions

** Note: amino acid like many molecules posses more than one functional

group (at least amino and carboxyl groups in the case of amino acids) 19Prepared by: Hamizah Othman



5)

Sulfhydryl

Group

y Consists of a sulf ur atom bonded to an atom of h ydrogen (resembles hydroxyl group in shape)

y Example: Cysteine (amino acid with SH group)

(R -SH)





- two sulfhydryl groups can react forming covalent bond called disulphide bond

- this cross-linking helps stabilize protein structure

- compounds with sulfyhydryl group are called thiol




6)

Phosphate

Group

y Consists of a phosphorus atom bonded to four oxygen atoms. ( one oxygen is bonded to the carbon

skeleton while another two oxygens carry negativecharges)

y Example: glycerol phosphate

(R -OPO3

2-

)





- strongly polar (ionized in water)- contributes negative charge to the molecules of

which it is a part

- has potential to react with water, releasing energy

- compounds with phosphate group are called asorganic phosphate




7) Methyl Groupy Consists of a carbon bonded to three h ydrogens

y The methyl group may be attached to a carbon or to a

different atomy Example: methyl cytidine (5 methyl cytidine is a

component of DNA that has been modified by addition of methyl group )

(R -CH3)





- methyl group is not reactive

- often acts as a recognizable tag on biological

molecules# Addition of methyl group to DNA or to molecules bound to DNA will affect expression of DNA

# Arrangement of methyl groups in male and female sex hormonesaffect their shape and functions

Testosterone (malesex hormone

Estradiol (femalesex hormone 25

Prepared by: Hamizah Othman



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You Should Be Able To:y Name the major functional groups found in organic

molecules;

y

Describe the basic structure of each functional groupy Outline the chemical properties of the organic

molecules in which they occur


CHAPTER 1_functional Group

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