2.3 Carbon-Based Molecules

KEY CONCEPTCarbon-based molecules are the foundation of life.

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

2.3 Carbon-Based Molecules

The Importance of the Carbon Backbone

• The carbon backbone allows large molecules to form, which make up life!

– Organisms use these molecules to build their bodies.– Carbon atoms can bind to each other or to other

atoms in an endless variety of shapes.– The different shapes that carbon can create are the

molecules necessary for life - Shape determines function!

2.3 Carbon-Based Molecules

Macromolecules

• Carbohydrates, lipids, proteins, and nucleic acids are referred to as macromolecules because of their large size.– Also called polymers

- They are made up of monomers.

2.3 Carbon-Based Molecules

• Macromolecules are made of many small subunits bonded together.– Monomers are the individual subunits.– Polymers are made of many monomers.

How are polymers formed??

13.1 Ecologists Study Relationships

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.

Simple carbs = sweet- tasting sugars

Complex carbs = starch, cellulose, chitin

2.3 Carbon-Based Molecules

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

• Carbohydrates’ function is to provide a quick source of energy for living things

Classification:

A. Monosaccharides– simple sugars– glucose, fructose,

galactose, ribose, deoxyribose

2.3 Carbon-Based Molecules

B. Disaccharides- Two monosaccharides chemically bonded together by

dehydration synthesis- Maltose, sucrose, lactose.

C. Polysaccharides - Complex carbohydrates

- polymers of monosaccharides formed by dehydration synthesis

- starch, glycogen, cellulose, chitin

13.1 Ecologists Study Relationships

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

2.3 Carbon-Based Molecules

Plants and animals each have different carbohydrates used for energy storage and structure

Carb. used to store energy:

Carb. used for structure:

Found in Plants:

Starch Cellulose

Found in Animals:

Glycogen Chitin (insects and crustaceans)

13.1 Ecologists Study Relationships

2.3 Carbon-Based Molecules

• Why is cellulose nondigestible in humans?

2.3 Carbon-Based Molecules

Lipids

• Lipids are nonpolar molecules that include fats, oils, and cholesterol.

• Insoluble in water due to hydrocarbon chains.

Classification:• Fats and Oils (Triglycerides)

– Contain glycerol and fatty acids- Glycerol- Contains three OH- groups.- Fatty acid- consists of long hydrocarbon chain.

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– Fats and oils contain fatty acids bonded to glycerol.

Triglyceride

2.3 Carbon-Based Molecules

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• Fats and oils contain different types of fatty acids. – saturated fatty acids

– unsaturated fatty acids

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Types of Fats and Fatty Acids

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Coronary Arteries and Plaque

2.3 Carbon-Based Molecules

• Phospholipids– Polar phosphate “head” (hydrophilic)– Nonpolar fatty acid “tails” (hydrophobic)

Phospholipid

2.3 Carbon-Based Molecules

Phospholipids

Cell membranes are made of phospholipids

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Lipids

• Steroids– Have skeletons of four fused carbon rings.

- Cholesterol, testosterone, estrogen

• Waxes– Long-chain fatty acid bonds with a long-chain

alcohol.- High melting point- Waterproof- Resistant to degradation- Made by insects

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• Lipids have several different functions.

– Long-term energy storage – broken down as a source of energy – make up cell membranes– used to make hormones

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Proteins

• Functions– Support– Enzymes– Transport– Defense– Hormones– Motion

2.3 Carbon-Based Molecules

• Proteins – are polymers of amino acid monomers.– Twenty different amino acids are used to build proteins

in organisms.

One amino acid

2.3 Carbon-Based Molecules

– Amino acids differ in side groups, or R groups.

• Proteins are polymers of amino acid monomers.

– Twenty different amino acids are used to build proteins in organisms.

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– Amino acids are linked by peptide bonds.

• Proteins are polymers of amino acid monomers.

2.3 Carbon-Based Molecules

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Proteins

• Protein Structure– Primary - Sequence of amino acids.– Secondary - Polypeptide coils or folds in a particular

fashion.– Tertiary - Folding and twisting that results in final

three-dimensional shape of a polypeptide.– Quaternary - Consists of more than one polypeptide.

2.3 Carbon-Based Molecules

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• 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

Hemoglobin

2.3 Carbon-Based Molecules

DEOXYRIBONUCLEIC ACID

RIBONUCLEIC ACID

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.

AG CorT

2.3 Carbon-Based Molecules

– DNA stores genetic information.

• Nucleic acids are polymers of monomers called nucleotides.

– Nucleotides are made of a sugar, phosphate group, and a nitrogen base.

– RNA builds proteins.

DNA

RNA

2.3 Carbon-Based Molecules

DNAComplementary base-pairing

2.3 Carbon-Based MoleculesATP: Adenosine triphosphate•A special nucleotide that contains A LOT of chemical energy•Energy is stored in the phosphate bonds•It is the “energy currency” for all living things