Nursing Entrance Exam

9.2 Life and Physical Science 9.2.1 Macromolecules For organisms to flourish, they must be able to break down the food they consume to get to the nutrients inside. The nutrients in the food are made up of two or more atoms, or molecules. There are four major classes of macromolecules: carbohydrates, lipids, nucleic acids, and proteins. There are four major macromolecules. They are: 1. Carbohydrates: Carbohydrates are any molecules made of sugar. Organisms use this sugar for energy by turning it into glucose. There are two types of carbohydrates, simple andcomplex. • Simple carbohydrates are made up of a few sugar molecules (e.g., table salt or fruit). • Complex carbohydrates contain lots of sugar molecules that are linked together. When you consume complex carbohydrates, such as breads, legumes, rice, or starchy vegetables, your body uses the sugar for energy and stores the leftover glucose in the liver and muscles as glycogen for later use. 2. Lipids: Molecules that contain hydrocarbons and are not soluble in water. Lipids, such as phospholipids, are used in the cell membrane (the part that protects the cell) to provide a barrier that marks the boundary of the cell. Other types of lipids like fats (typically stored by animals) and oils (typically stored by plants) are used as a secondary energy source. When organisms run out of carbohydrates, they will use lipids for energy. Lipids yield large amounts of energy when broken down. 3. Nucleic acids: Nucleic acids are made of many nucleotides and can be thought of as the building blocks of living organisms because they contain the genetic code of that organism. There are many types of nucleic acids, such as DNA, RNA, mRNA, and tRNA. The order in which the nucleotides store information is what tells the cell how to make a certain protein. 4. Proteins: Comprised of smaller molecules called amino acids, which form polypeptide chains. The body uses protein macromolecules for many different functions depending on its shape. For example, some protein is used to help us grow our hair and nails or repair our skin when we get a cut. One specific type of protein is called an enzyme. Enzymes will catalyze biochemical reactions by speeding up chemical reactions. For example, the enzymes in washing detergents help break down stains on clothes. 9.2.2 Chromosomes, Genes, Proteins, DNA, and RNA The concepts of genes, chromosomes, proteins, RNA, and DNA are all interrelated genetic terms. Chromosomes are made up of genes, the DNA contains the chromosomes, and the RNA interprets and implements the information in the RNA. Here is a breakdown of each of them.

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