2.3 Carbon-based Molecules

Key Concept: Carbon-based molecules are the basis of life.

How is carbon different from other atoms?

Why is it essential to living things?

Carbon atoms have unique bonding properties.

Carbon forms covalent bonds (strong bonds) with up to four other atoms, including other carbon atoms

Carbon-based molecules have three general types of structuresStraight chainBranched chain (3-D structures)Ring

Carbon can form single, double, or triple bonds

Carbon forms isomers Isomers are compounds that have the same

chemical formula, but different structural formulas Example: C4H10

Only carbon has these characteristics

Carbon atoms have unique bonding properties.

Many carbon-based molecules are made of many small subunits bonded together.

Monomers are the individual subunits.

Polymers are made of many monomers.

Four main types of carbon-based molecules are found in living things.

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic acids

CarbohydratesMolecule Carbohydrates

Has Carbon  All of the time

Has Hydrogen

All of the time 

Has Oxygen All of the time 

Has Nitrogen  -

Has Phosphorus

 -

Monomer  monosaccharide

Polymer disaccharide (dimer), polysaccharide 

Examples Monosaccharide:  glucose, fructoseDisaccharide: sucrose (table sugar)

Polysaccharide: starch & cellulose (cell wall in plants),

glycogen (in animals)Unique - Provide a quick source of energy

LipidsMolecule Lipids

Has Carbon All of the time Has Hydrogen

All of the time 

Has Oxygen All of the time Has Nitrogen

 Some of the time

Has Phosphorus

Some of the time 

Monomer  glycerol & fatty acids; polar heads & fatty acid tails

Polymer  triglycerides; phospholipidsExamples Fats, oils, cholesterol, steroids, waxes,

phospholipidsUnique - Nonpolar

- Broken down to provide energy- Used to make steroid hormones (control

stress, estrogen, testosterone)- Phospholipids make up all cell

membranes  - Fats and oils contain fatty acids bonded to

glycerol

ProteinsMolecule Proteins

Has Carbon  All of the time

Has Hydrogen

All of the time 

Has Oxygen All of the time 

Has Nitrogen

All of the time 

Has Phosphorus

- 

Monomer Amino acid 

Polymer Polypeptide (protein) 

Examples Enzymes,  hemoglobin (in blood), muscle movement, collagen

Unique - 3D structure makes them active - Peptide bonds hold amino acids together- Have a side group (R) that makes each

amino acid (and therefore protein) different

- Sometimes may contain sulfur

Nucleic acidsMolecule Nucleic acids

Has Carbon  All of the time

Has Hydrogen

All of the time 

Has Oxygen All of the time 

Has Nitrogen All of the time 

Has Phosphorus

All of the time 

Monomer  Nucleotide (5-carbon sugar, phosphate group, & base)

Polymer Nucleic acid 

Examples DNA & RNA 

Unique  - Order of the bases makes every living thing unique

- DNA stores genetic information- RNA builds proteins

Building & Using Carbon-based Molecules

Building (process): dehydration synthesisRemoval of water to make a new product

Using (process): hydrolysisBreaking apart using water

Dehydration Synthesis

Two monomers need to joinOne monomer loses (-OH) and one loses (-H) The two monomers join and the (-OH) and (-H) join,

forming H2O

A-OH + B-H AB + HOH (H2O)

HydrolysisA polymer needs to break apart (the carbs,

proteins, and lipids we ingest are too big for us to use)Water breaks apart into (-OH) and (-H) and splits the

polymer into monomersThe (-OH) and (-H) bond to each monomer to make

them stable molecules

AB + HOH (H2O) A-OH + B-H

What’s in a mixture?

What’s in a molecule?

Macromolecules Gone Wild (Bio Style)Gangnam parody