Chapter 3 Flashcards
(17 cards)
Polar molecules
a. dissolve in lipids.
b. are hydrophobic.
c. contain covalent bonds.
d. contain ionic bonds.
d
Which match is correct?
a. monosaccharide–sucrose
b. polysaccharide–maltose
c. disaccharide–lactose
d. disaccharide–glycogen
c
Which of the following statements is false?
a. In starch breakdown, water is formed.
b. In chitin, glucoses are linked as in cellulose.
c. Peptide bonds determine primary peptide structure.
d. Disulfide bridges are formed by covalent bonds.
a
Which of the following is not composed of repeating subunits?
a. starch
b. protein
c. nucleic acid
d. lipid
d
Which of the following statements is false?
a. Carbohydrates are the most efficient energy-storage molecules by weight.
b. Lipids are not soluble in water.
c. Nucleotides may act as energy-carrier molecules.
d. Very acidic or salty solutions may denature proteins.
a
In organic molecules made of chains of subunits, each subunit is called a(n)______, and the chains are called_______. Carbohydrates consisting of long chains of sugars are called_______. These sugar chains can be broken down by_______reactions. Three types of carbohydrates consisting of long glucose chains are________,_________, and__________.
monomer, polymers; polysaccharides; hydrolysis; (any three) cellulose, starch, glycogen and chitin
Fill in the following with the specific bond(s): Maintain(s) the helical structure of many proteins:_________; link(s) polypeptide chains and can cause proteins to bend:________and________; join(s) the two strands of the double helix of DNA:_________; link(s) amino acids to form the primary structure of proteins:_________.
hydrogen bond, hydrogen and disulfide bonds, hydrogen bond and peptide bond
Proteins are synthesized by a reaction called_______synthesis, which releases________. Subunits of proteins are called_________. The sequence of protein subunits is called the__________ structure of the protein. Two regular configurations of secondary protein structure are ________ and ____________. When a protein’s secondary or higher-order structure is destroyed, the protein is said to be__________. .
dehydration, water; amino acids; primary; helix, pleated sheet and denatured
A nucleotide consists of three parts:________, _________, and _________. A nucleotide that acts as an energy carrier is ________. The four bases found in _________ deoxyribose nucleotides are _________ , ________ ,________, and ________. Two important nucleic acids are _________ and _________. The functional group that joins nucleotides in nucleic acids is ________. .
ribose sugar, base, phosphate; adenosine triphosphate (ATP); adenine, guanine, cytosine, thymine; deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and phosphate
What does the term “organic” mean to a chemist?
“Organic” describes molecules with a carbon backbone that usually also contain hydrogen and oxygen.
Fill in the following with the appropriate type of lipid: Unsaturated, liquid at room temperature:_________; bees use to make honeycombs:__________; stores energy in animals:_________; sex hormones are synthesized from these:_________; the LDL form of this contributes to heart disease:_________; a major component of cell membranes that has polar heads:_________. .
oil, wax, fat, steroids, cholesterol and phospholipid
List the four principal classes of biological molecules, and give an example of each.
Carbohydrates—glucose, sucrose, starch, glycogen, cellulose, chitin
Lipids—oil, fat, waxes, cholesterol
Proteins—keratin, silk, hemoglobin
Nucleic acids—DNA, RNA
What roles do nucleotides play in living organisms?
ATP serves as a short-term energy storage molecule; cyclic AMP is an intracellular messenger. The nucleotides adenine, guanine, cytosine and thymine are subunit monomers used in assembling the nucleic acids DNA and RNA.
How are fats and oils similar? How do they differ, and how do their differences explain whether they are solid or liquid at room temperature?
Fats and oils both consist of a glycerol molecule with each of its carbons bonded to a fatty acid “tail.” They differ in that oils have fewer hydrogen atoms bonded to the carbons in their fatty acid tails, causing double bonds between the carbons, which cause the tails to kink. This keeps the molecules from packing closely together, so oil remains liquid at room temperature. Fats are saturated with hydrogen atoms, their tails are straight, and they pack closely, so fat remains solid at room temperature.
Describe and compare dehydration synthesis and hydrolysis. Give an example of a substance formed by each chemical reaction, and describe the specific reaction in each instance.
Dehydration synthesis forms polymers by removing a water molecule from two monomers that then become bonded together. A hydroxyl group is removed from one monomer and a hydrogen atom from the other. For example, dehydration synthesis links glucose and fructose to form sucrose. Hydrolysis breaks polymers into monomer subunits by adding water to split the bonded monomers apart. For example, sucrose is hydrolyzed into glucose and fructose.
Describe the synthesis of a protein from amino acids. Then describe the primary, secondary, tertiary, and quaternary structures of a protein.
Proteins are produced by dehydration synthesis of amino acids to form polypeptides linked by peptide bonds. Primary structure is the sequence of amino acids; secondary structure involves bending the polypeptide into helices or pleated sheets, stabilized by hydrogen bonds between amino acids; tertiary structure is the folding of a polypeptide into a complex, three-dimensional structure involving hydrogen and sometimes disulfide bonds between amino acids in different parts of the molecule; and quaternary structure is the association of more than one polypeptide into a closely packed arrangement, usually maintained by hydrogen bonds, disulfide bonds, and/or attractions between oppositely charged polar portions of amino acids.
Where in nature do we find cellulose? Where do we find chitin? In what way(s) are these two polymers similar? How are they different?
Cellulose is found in plant cell walls. Chitin is found in the exoskeletons of animals and in many fungal cell walls. They are similar in that they are composed of glucose subunits; however, in chitin, a hydroxyl group in the glucose subunits is replaced by a nitrogen-containing functional group.
