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