Characteristics and Classification of Life Chapter 2 Characteristics and Classification of Life

Chapter 2B Molecules and Life

II. Molecules and Life A. Molecules

Molecules The simplest structural unit of an element or compound.

A. Molecules Made of smaller units called atoms. There are many different types of molecules in each living cell.

A. Molecules Four general categories of molecules in cells: 1. Carbohydrates 2. Lipids (fats) 3. Proteins 4. Nucleic acids

1. Carbohydrates Important storage molecule Made only of carbon, hydrogen, and oxygen atoms Sugars and starches Glucose (most common) Cellulose, starch, glycogen

2. Lipids Important storage, structural, and transport molecule Made only of carbon, hydrogen, and oxygen atoms Energy storage Main component of cell membranes

3. Proteins Building blocks for different parts of a cell. Enzymes: regulate life-supporting processes Composed of amino acids

4. Nucleic Acids Contain all the instructions that living cells need to make proteins and maintain life Composed of nucleotides Examples: DNA and RNA

Nucleic Acids DNA and RNA The arrangement of the nucleotides in DNA forms a code. The DNA code determines the order of amino acids in a protein.

Nucleic Acids DNA and RNA RNA helps make proteins by using the coded instructions in DNA.