Cell membranes consist of lipid, protein, and carbohydrate in relative amounts that vary according to cell type. Describe the relative proportions of these substances in three structures, and relate these differences to cell function where possible.
What will be an ideal response?
(Note to instructor: This may be a good question to use on a comprehensive final exam, as it ties together basic membrane composition with cell functions revealed in later chapters.) See Table 3.1 in the chapter. Red blood cells have nearly equal amounts of protein and lipid, with a small amount of carbohydrate, in this ratio of protein:lipid:carbohydrate: 49:43:8. Myelin is almost all lipid, followed by protein and carbohydrate in this ratio of lipid:protein:carbohydrate: 79:18:3. In later chapters on the nervous system, it will be seen that this preponderance of lipid results in electrical insulation, which is one of the main functions of myelin. The inner mitochondrial membrane is mostly protein, in this ratio of protein:lipid:carbohydrate: 76:24:0. This reflects the function of this membrane in chemical synthesis that relies on a variety of protein enzymes.
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Which of the following lists exclusively contains only variables that determine a person's basal metabolic rate?
A. gender, weight, age, and muscular activity B. age, height, and recent ingestion of food C. environmental temperature variations, body surface area, and emotional state D. gender, age, body surface area, and circulating levels of thyroid hormone E. environmental temperature, muscular activity, and emotional state
_______ _________ is a measure of the force exerted by blood against the blood vessel walls
Fill in the blank(s) with the appropriate word(s).
Which of the following completely encloses the embryo and provides it with a stable environment?
A. Yolk sac B. Amnion C. Chorion D. Chorionic villus E. Allantois
The hormones that maintain the uterine wall during the last 5 to 6 months of pregnancy
are A) placental lactogen and relaxin. B) FSH and LH. C) human chorionic gonadotropin and synthetic estrogen. D) placental estrogen and progesterone.