The Molecules of Cells

Section 2.3

Macromolecules

• Carbohydrates• Proteins• Lipids• Nucleic Acids• All organic (contain carbon).• Only produced in living things.

Carbohydrates• Contain C, H, O atoms.• Monosaccharides– Immediate energy source– Simple sugars, ex. Glucose used to build polymers

• Disaccharides– Used by plants to store or transport glucose.– Sucrose, maltose, lactose

• Polysaccharides– Long polymers made of glucose monomers– Ex. Amylose, cellulose (plant starches), glycogen (animal starch)

Lipids

• Store energy• 3 Groups– Triglycerides• Animal fats, plant oils

– Phospholipids• Compose cell’s membranes.

– Steroids• Act as hormones (estrogen, testosterone, venom,

cholesterol.

Proteins

• Amino acids are the monomers of proteins.• More than 75% of the dry mass of a cell is

protein.• Cells produce more than 2,000 proteins• 9 Categories, p. 53– Structural, enzyme, transport, contractile,

hormone, antibody, pigment, recognition, toxins

Nucleic Acids• Composed of nucleotides

– Nitrogen base, 5-carbon sugar, phosphate group

• DNA: deoxyribonucleic acid– Double-stranded– Found in nucleus of eukaryotes, and cytoplasm of prokaryotes– Contains our genetic code

• RNA: ribonucleic acid– Single-stranded– Found in cytoplasm of cells– Used to make proteins