Carbon-based molecules like carbohydrates, lipids, proteins, and nucleic acids are the foundation of life. They have unique structures and functions. Carbohydrates include sugars and starches that can provide energy or be part of cell structure. Lipids include fats, oils, and phospholipids that form cell membranes and can also provide energy. Proteins are made of amino acids linked through peptide bonds and perform important functions like movement and chemical reactions. Nucleic acids like DNA and RNA store genetic information and build proteins.

1. 2.3 Carbon-Based Molecules
KEY CONCEPT
Carbon-based molecules are the foundation of life.

2. 2.3 Carbon-Based Molecules
Objectives:
• Describe the bonding properties of carbon atoms.
• Compare carbohydrates, lipids, proteins and nucleic
acids.

3. 2.3 Carbon-Based Molecules
• Carbon is often called the building block of life because it is
the basis of most molecules that make up living things.

4. 2.3 Carbon-Based Molecules
Carbon atoms have unique bonding properties.
• Carbon forms covalent bonds with up to four other atoms,
including other carbon atoms.
• Carbon-based molecules have three general types of
structures.
– straight chain
– branched chain
– ring

5. 2.3 Carbon-Based Molecules
• Many carbon-based molecules are made of many small
subunits bonded together called monomers.
– Monomers are the individual subunits.
– Polymers are large molecules made of many
monomers.

6. 2.3 Carbon-Based Molecules
Four main types of carbon-based molecules are found in
living things.
• Carbohydrates are made of carbon, hydrogen, and
oxygen.
• Fruits contain six carbon sugar called Fructose.

7. 2.3 Carbon-Based Molecules
Four main types of carbon-based molecules are found in
living things.
• Carbohydrates are made of carbon, hydrogen, and
oxygen.
– Carbohydrates include
sugars and starches.
– Monosaccharide's are
simple sugars.
– Polysaccharides include
starches, cellulose, and
glycogen.

8. 2.3 Carbon-Based Molecules
• Carbohydrates can be broken down to provide
energy for cells.
• Some carbohydrates are part of cell structure.
Polymer (starch)
Starch is a polymer of
glucose monomers that
often has a branched
structure.
Polymer (cellulose)
Cellulose is a polymer
of glucose monomers
that has a straight, rigid
structure
monomer

9. 2.3 Carbon-Based Molecules
Carbohydrate Type Composition and presence
Starches Branched chain
Made and stored in plants
Glycogen Made and stored in animals
Highly branched than plant
starches
Cellulose Straight structure
Present in plant cell
Make cell wall in plants
Present in vegetables like
celery.

10. 2.3 Carbon-Based Molecules
– Many contain carbon chains bonded by hydrogen
atoms called fatty acids.
– Fats and oils contain fatty acids bonded to glycerol.
– Many lipids contain three fatty acids bonded to
glycerol called Triglycerides.
• Lipids are nonpolar molecules that include fats, oils, and
cholesterol.
Triglyceride

11. 2.3 Carbon-Based Molecules

12. 2.3 Carbon-Based Molecules
• Fats and oils have different types of fatty acids.
– saturated fatty acids
– unsaturated fatty acids

13. 2.3 Carbon-Based Molecules
Lipids:
Saturated fatty acids
• All carbon-carbon bonds
are single bonds.
• Maximum number of H-
atoms.
(Oils)
Unsaturated fatty acids
• They have at least one
carbon-carbon double
bond.
• Minimum number of
hydrogen atoms.

14. 2.3 Carbon-Based Molecules
• Lipids have several different functions.
– broken down as a source of energy
– make up cell membranes
– used to make hormones

15. 2.3 Carbon-Based Molecules
• Phospholipids make up all cell membranes. It consists of
glycerol, two fatty acids and one phosphate group.
– Polar phosphate “head”
– Nonpolar fatty acid “tails”
Phospholipid

16. 2.3 Carbon-Based Molecules
Cholesterol:
• Ring structure
• Present in eggs
• Part of cell membrane
• Steroid hormones are made up of lipids.
• Function is body response to stress and others help in
the reproductive system.

17. 2.3 Carbon-Based Molecules
• Proteins are polymers of amino acid monomers.
– Twenty different amino acids are used to build
proteins in organisms.

18. 2.3 Carbon-Based Molecules
– Amino acids differ in side groups, or R groups.
Three parts are same in every amino acids:
•Hydrogen atom
•Amino group NH2
•Carboxyl group COOH

19. 2.3 Carbon-Based Molecules
– Amino acids are linked by peptide bonds.
– Through peptide bonds, amino acids are linked together
to form chain called polypeptide.

20. 2.3 Carbon-Based Molecules
• Proteins differ in the number and order of amino acids.
– Amino acids interact to give a protein its shape.
– Incorrect amino acids change a protein’s structure
and function.
hydrogen bond
Hemoglobi
n

21. 2.3 Carbon-Based Molecules
If a protein has incorrect order of amino acids, the
structure change in the way that prevents the protein
from working properly. Just one wrong amino acid of the
547 amino acids in the hemoglobin causes the disorder
of sickle cell anemia.

22. 2.3 Carbon-Based Molecules
• Nucleic acids are polymers of monomers called
nucleotides.

23. 2.3 Carbon-Based Molecules
– Nucleotides are made of a sugar, phosphate
group, and a nitrogen base.
A phosphate group nitrogen-containing molecule,
called a base
deoxyribose (sugar)
• Nucleic acids are polymers of monomers called
nucleotides.

24. 2.3 Carbon-Based Molecules
– DNA stores genetic
information to make
proteins.
– RNA builds proteins.
DNA
RNA
Two types of nucleic acids:
DNA RNA

25. 2.3 Carbon-Based Molecules
DNA
• Double stranded
• Decoy-ribose sugar
• Stores genetic
information to make
protein.
• Only one type
RNA
• Single stranded
• Ribose sugar
• To build proteins
• 3 different types as
mRNA, tRNA, rRNA

26. 2.3 Carbon-Based Molecules
Functions & Examples:
Molecule Type Functions Examples
CARBOHYDRATE Broken down as a source
of energy
Part of cell structure
Sugars
Starches
Cellulose
LIPID Broken down as a source
of energy
Part of cell structure
Fats
Oils
Phospholipids
PROTEIN Movement
Transport
Chemical catalysts
Enzymes
Hemoglobin
NUCLEIC ACID Stores genetic information
Build proteins
DNA
RNA