Chapter 3: The Molecules of Cells

Building Maltose, a Double Sugar

Lipids

1. Lipids are diverse compounds that are grouped together because they are hydrophobic.
2. A fat molecule is composed of two types of smaller molecules: glycerol and fatty acids.
3. A fatty acid consists of a carboxyl group and a long hydrocarbon chain.
4. Unsaturated fatty acids have one or more double bonds in their hydrocarbon chains and are usually found in vegetable oils.
5. The hydrocarbon chains of saturated fatty acids are not kinked, and thus pack closely together, making animals fats solid at room temperature.
6. Phospholipids are a major component of cell membranes. They form a bilayer with their hydrophobic tails mingling together and their hydrophilic heads facing the watery environment on both sides of the membrane.
7. Steroids are lipids with a structure consisting of four fused rings. Many sex hormones are made from this type of lipid.

DNA Structure

Part A: Which of the following is the largest unit of DNA organization? – Genome

Part B: A sugar, a phosphate, and a base are the components of a nucleotide.

Part C: A page is to a book as a gene is to the genome.

Part D: How many polynucleotides are found in one molecule of DNA? – two

Part E: Which of the following make up the back bone of a polynucleotide strand? – sugar and phosphate

Nucleic Acid

1. Nucleic acids are polymers of nucleotides.
2. The monomers of nucleic acids consist of a phosphate group, a five-carbon sugar, and a nitrogenous base.

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