4.6 Organic Chemistry and Macromolecules Flashcards
- Denaturation of proteins involves disruption of the
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Covalent bonding
Answer is C: Protein “tertiary structure” is held together by the relatively weak attraction between different parts of the protein molecule known as “hydrogen bonding”. This structure is the most easily disrupted.
- One of the following is NOT a function of lipids in the body. Which one?
A. Function as coenzymes
B. Used in phospholipids
C. Used to make prostaglandins
D. Steroids are produced from them
Answer is A: Coenzymes are proteins (not lipids).
- Amino acids are the building blocks of all proteins. As more amino acids are added, the protein chain tends to fold upon itself in a characteristic way. This characteristic of a protein is called the:
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure
Answer is C: The shape produced by folding is the tertiary structure. Primary struc- ture is the sequence in which the amino acids are joined. Secondary structure is any repetition of the primary structure. Quaternary structure does not exist.
- Which of the following is the correct combination for the nucleic acid DNA?
A. Phosphate, ribose, uracil
B. Phosphate, deoxyribose, uracil C. Phosphate, ribose, adenine
D. Phosphate, deoxyribose, adenine
Answer is D: “Deoxyribose” supplies the “D” in DNA. The base uracil occurs in RNA (not DNA) where it substitutes for the thymine that occurs in DNA.
- To which of the following class of biological compounds do all enzymes belong?
A. Hormones
B. Proteins
C. Carbohydrates
D. Lipids
Answer is B: All enzymes are proteins.
- The twisting of a polypeptide chain into a characteristic shape such as a helix is an example of which of the following?
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure
Answer is C: The shape of the protein molecule is the tertiary structure of the protein.
- Which one of the following is NOT a steroid compound?
A. Stearic acid
B. Estrogen
C. Cholesterol
D. Testosterone
Answer is A: Stearic acid is a fatty acid. The sex hormones estrogen and testosterone are derived from cholesterol.
- Which of the following carbohydrates are able to pass through the plasma membrane?
A. Disaccharides
B. Sucrose
C. Glycogen
D. Monosaccharides
Answer is D: For example, glucose maybe absorbed from the gut by passing through the plasma membrane of the cells lining the gut. Glucose is also absorbed by cells for respiration inside mitochondria.
- Which of the following foods when catabolised in the body produces the highest yield of energy?
A. 100 g of fat
B. 100 g of chocolate
C. 100 g of carbohydrate D. 100 g of protein
Answer is A: Fat is higher in energy (kilojoules) than either protein or carbohydrate. Chocolate has sugar (carbohydrate) as well as fat as an ingredient.
- Fructose is a simple sugar or carbohydrate. What is it an example of? A:
A. Monosaccharide
B. Disaccharide
C. Polysaccharide
D. Oligosaccharide
Answer is A: Fructose is a simple sugar or monosaccharide – it cannot be converted to a simpler sugar by hydrolysis.
- Cells use glucose as an energy source but store it as glycogen. When needed the glycogen is broken down by a process called:
A. Glycolysis
B. Glycogenesis
C. Gluconeogenesis
D. Glycogenolysis
Answer is D: Glycogen – o – lysis refers to the lysis (splitting) of glycogen into smaller glucose units.
- A lipid such as oleic acid contains a number of double bonds in the carbon chain. Because of this, what term is applied to it?
A. Monounsaturated
B. Diunsaturated
C. Polyunsaturated
D. Saturated
Answer is C: “Unsaturated” because addition hydrogen atoms may be attached to the carbon bonds if the double bond was replaced by a single bond. “Poly-” because there is more than one instance of a double bond between adjacent carbon atoms.
- What are the structural components of proteins?
A. Amino acids
B. Fatty acids
C. Peptides
D. Monosaccharides
Answer is A: Peptides are used for several amino acids joined together.
- Which of the following chemical formulae represents a typical carbohydrate?
A. Ca10(PO4)6(OH)2
B. N2C5H12O4
C. C120H240O120
D. C57H110O6
Answer is C: A carbohydrate is composed of carbon, hydrogen and oxygen atoms. Usually there are twice as many H atoms as C atoms. Choice D, having relatively few O atoms, is typical of a lipid.
- Proteins perform a wide range of functions in the body including which one of the following?
A. They are our major source of energy.
B. They act as enzymes.
C. They are used to make sex hormones.
D. They are necessary for the absorption of vitamins A, D, E and K.
Answer is B: All enzymes are proteins. Carbohydrates should be the major energy source. Choice D lists the fat soluble vitamins.
- Which of the following refers to a carbohydrate?
A. Diglycerol
B. Adenosine diphosphate
C. Disaccharide
D. Dipeptide
Answer is C: A disaccharide is a sugar (hence a carbohydrate) that can be simplified into simpler sugars.