Biochemistry

Functional Groups

Carbon—The Backbone of Biological Molecules

All living organismsAre made up of chemicals based mostly on

carbon due to its bonding abilityAll life considered “carbon based life-forms”

Chapter 4• Organic chemistry

–the study of carbon compounds

• Organic compounds have carbon in them (& usually H)–Exception: CO2 is considered INORGANIC

–Range from simple to big molecules

Organic? • For a long time, the term organic was

strictly associated with the chemistry of life. Until scientists gained the ability to synthesize carbon compounds, the only “factories” making carbon compounds were living organisms, hence the connection to “all natural”.

Formation of Bonds w/ Carbon

• Carbon atoms– forms diverse molecules

–b/c carbon has 4 valence electrons bind to to 4 other atoms

–can form 4 covalent bonds with itself or other atoms very important in living things!

• Carbon has bonding versatility –allows it to form many diverse

molecules, including carbon skeletons (carbon “chains”)

The electron configuration of carbon

Gives it covalent compatibility with many different elements

H O N C

Hydrogen

(valence = 1)

Oxygen

(valence = 2)

Nitrogen

(valence = 3)

Carbon

(valence = 4)

Figure 4.4

Molecular Diversity Arising from Carbon Skeleton Variation

Carbon chainsForm skeletons of most organic molecules

Vary in length and shape

StraightBranchedRings

Hydrocarbons

• Organic molecules consisting of only C and H

• Ex: petroleum; lipid ‘tails’

• Found in many of cell’s organic molecules

• Ex: fat molecules

• Covalent bonding btw C-H nonpolar (hydrophoic)

• High energy storage

Example of a Hydrocarbon

(a) A fat molecule (b) Mammalian adipose cells

100 µm

Fat droplets (stained red)

Figure 4.6 A, B

Functional Groups

• Functional groups –parts of organic molecules involved in chemical rxns (i.e.-chemically reactive groups)

–each functional group behaves in a consistent fashion from 1 organic molecule to the next

–# & arrangement of groups helps give molecules unique, distinctive chemical properties

6 functional groups important in chemistry of life

1.Hydroxyl2.Carbonyl3.Carboxyl4.Amino5.Sulfhydryl6.Phosphate7.Methyl (yes…another one)

Functional GroupsAttachments replace 1+ of H’s bonded

to C skeleton of the hydrocarbonEach GROUP are HYDROPHILIC

increase organic molecule solubility in water

1. Hydroxyl Group (-OH) –H bonded to O –Make alcohols, sugars–polar (b/c of oxygen electronegivity)

–soluble in water (attracts H20)

Ethanol and Sugar

• Ethanol:

• Sugar:

Functional Groups2. Carbonyl Group (C=O)

–C double bond to O–Aldehyde (at the end of C skeleton)–Ketone (INSIDE Carbon skeleton)–Ex: Acetone, Propanal

• Ketone

• Aldehyde– **Think: all the way

at the end!

Functional Groups cont’d3. Carboxyl Group (-COOH)

• O double bonded to C to hydroxyl• Carboxylic acids (organic acids)• Covalent bond between O and H• Polar

Functional Groups cont’d4. Amino Group (-NH2)

• N to 2 H atoms• Makes Amines • Acts as a base (+1) • Also makes AMINO ACIDS Have both amino and

carboxyl groups

Functional Groups cont’d

5. Sulfhydral Group (-SH)

• sulfur bonded to H

Functional Groups cont’d6. Phosphate Group (-OPO3

-)• Organic

phosphates

Functional Groups cont’d7. Methyl Group

(-CH3)• Usually not as

reactive as other groups

• Used in gene expression

Male or Female!!

Only one little itty bitty difference that separates the sexes