Protein assignment
The primary structure of proteins is the amino acid_____of the protein chain. The primary structure is formed by the_____bonds between amino acids in the protein chain.
Sequence, peptide bonds
As protein molecules unfold and become entangled, coagulation occurs, and the protein molecules have aggregated to become a ______.
Solid
When the pH of a solution is changed dramatically, the acid or base will change the charge of the protein, interfering with the ______ structure of the protein.
Teritary
Disulfide bridges, salt bridges, hydrogen bonds, and hydrophobic interactions are features of the ______ structure of proteins.
Tertiary
Fibrous proteins are typically_____in water; globular proteins are typically_____in water.
Insoulble, Soluble
-------are the most abundant macromolecules in the cell and can act to catalyze reactions, transport materials, and regulate functions.
Proteins
Which of the following are properties of collagen?
-Collagen is used in cosmetic procedures and also in the preparation of artificial skin for burn patients. -Collagen is rich in glycine amino acids. Every third amino acid is glycine. -Collagen gives mechanical strength to bone, tendon, skin, and blood vessels. -Collagen is the most abundant protein in humans.
What statements correctly describe fibrous proteins?
-Fibrous proteins such as α-keratins are insoluble in water. -Fibrous proteins are structural proteins. -Fibrous proteins are arranged in fibers or sheets.
Select all the statements that correctly describe the oxygenation of hemoglobin.
-Hemoglobin has four heme groups and can bind four oxygen molecules. -Oxygenation of hemoglobin is dictated by the partial pressure of oxygen in the lungs and blood.
Identify the feature(s) of a β-sheet.
-Polypeptide chains can have two orientations: parallel and antiparallel. -Hydrogen bonding occurs between two regions of the protein chain.
Identify factors associated with sickle cell anemia.
-Red blood cells with sickle cell hemoglobin become elongated and crescent shaped. -Sickle cell anemia results from the change of a single amino acid in hemoglobin. -Sickle cell anemia is a genetic disorder that must be inherited from both parents. -Red blood cells with sickle cell hemoglobin can cause damage to organs, including bone and kidney.
Identify the feature(s) of an α-helix.
-The carbonyl oxygen is hydrogen-bonded to the amide hydrogen four amino acids away in the chain. -Every amide hydrogen and carbonyl oxygen along the peptide backbone is involved in a hydrogen bond.
Indicate the type of intermolecular force that is generally present between the side chains of the following amino acids.
-Thiol-containing R groups: Disulfide bond -Nonpolar R groups: London dispersion forces -Polar R groups: Hydrogen bonds -Oppositely charged R group: Ionic bonds
Select the statements that correctly describe the naming of peptides.
-When naming C-terminal amino acid in a peptide, the entire name of the amino acid is used. -To name a peptide, start at the N-terminus and end with the C-terminus. -Peptides are named as derivatives of the C-terminal amino acids.
Which of the following are features of α-keratins?
-α-Keratins have three α-helices coiled into a protofibril that becomes a part of a microfibril. -α-Keratins are the proteins found in hair and nails. -α-Keratins are mainly composed of α-helices coiled in bundles of three helices.
Select the statement that best describes the term "zwitterion."
A zwitterion contains equal numbers of positive and negative charges.
Match the type of blood protein with the correct description.
Albumin: Most abundant protein in the blood; transports metabolites that are not soluble in water α-globulins: Class of proteins that includes glycoproteins, high-density lipoproteins, haptoglobin, and prothrombin β-globulins: Class of proteins including transferrin and low-density lipoprotein γ-globulins: Immunoglobulins; synthesized in the B lymphocytes Fibrinogen: Protein involved in coagulation
What is produced by the hydrolysis of proteins?
Amino acid
What is produced by the hydrolysis of proteins?
Amino acid, smaller peptides
What type of biomolecule contains two functional groups; a protonated amino group (NH3+) and a carboxylate group (COO-)
Amino acids
Identify the component(s) present in every amino acid.
An α-carbon A carboxylate group A protonated amino group
What statement correctly describes the effect of temperature on a protein?
As temperature increases, it is chiefly the nonbonding interactions in the protein that are broken, disrupting the structure.
Which of the following amino acids have R groups that are not ionized at pH 7?
Asparagine Glutamine Serine
Which of the following amino acids are negatively charged at a pH of 7?
Aspartic Acid Glutamic acid
What are the dietary purposes of proteins?
Biosynthesis of nitrogen compounds Energy source Biosynthesis of new proteins
In a protein, the amino acid with free amino group is known as the N-terminus and the amino acid with the free_____group is known as the C-terminus. The structure of a protein is written with the N-terminus on the_______
Carboxyl group, left
Identify the functional group(s) present in every amino acid.
Carboxylate group Protonated amino group
Protein molecules in solution can unfold and aggregate to become a solid. At this point, the protein is no longer in solution. This is known as _____.
Coagulation
The most abundant protein in the human body is_____ and is used in a variety of ways due to its tensile strength, flexibility, and transparency.
Collagen
Match the protein classification with the correct description.
Complete protein: Protein derived from animal sources or soy; provides all essential and nonessential amino acids Incomplete protein: Protein derived from most vegetable sources; lacks sufficient amounts of one or more essential amino acids
The process that alters organized structures of a protein such as the secondary and tertiary structure without altering the primary structures is called______
Denaturation
When ______ interact with proteins, they primarily disrupt hydrophobic interactions, causing the protein chain to unfold.
Detergent
Isoleucine, threonine, and valine are______amino acids because they cannot be synthesized by the body.
Essential
Match the class of amino acids to the correct description.
Essential amino acids: Amino acids that cannot be synthesized by the body Nonessential amino acids: Amino acids that can be synthesized in the body
In the tertiary structure of a protein, each individual polypeptide chain is called a subunit of the overall protein. (T/F)
False
T/F Proteins are linear polymers of amino acids in which the carboxyl group of one amino acid is linked to the carboxyl group of another amino acid.
False
T/F There is free rotation about the -N-C-C- single bonds of the peptide backbone.
False
A fetus receives its oxygen from its mother by simple diffusion, but the ______ hemoglobin of the fetus has a higher affinity for oxygen than the mother's hemoglobin.
Fetal
Blood plasma contains 60-80 g/L of proteins that are separated into five classes. Which of the following are among the five classes?
Fibrinogens Albumins α-Globulins
Identify the amino acid that does not have a chiral α-carbon.
Glycine
Many receptor proteins on cell surfaces are_____proteins with sugar groups covalently attached.
Glycoproteins
A molecule of ______ is produced during the formation of a peptide bond.
H2O
How do heavy metals affect the conformation of a protein?
Heavy metals can bind to negatively charged side chains, interfering with salt bridges. Heavy metals can bind to sulfhydryl groups.
Which of the following statements correctly describes features of hemoglobin?
Hemoglobin transports oxygen to wherever it is needed in the body.
Match hemoglobin and myoglobin with the correct description.
Hemoglobin: This protein consists of four polypeptide chains and four heme units. Myoglobin: This protein consists of a single polypeptide chain and one heme unit.
Fetal hemoglobin has a ______ affinity for oxygen than adult hemoglobin, allowing for ______ efficient transfer of oxygen to the fetal blood.
Higher, more
Polar organic solvents denature proteins by disrupting the ______ within the protein, and the conformation of the protein is affected by the ______ region of the solvents.
Hydrogen bonds, nonpolar
The secondary structure of proteins is formed by the_____bonding between the amide hydrogen atoms and the carbonyl_____of the peptide bonds.
Hydrogen, Oxygens
Amino acids are liberated by the _____ of dietary proteins.
Hydrolysis
______ is a process that breaks the amide bonds that comprise the primary structure of a protein.
Hydrolysis
Match the term with its definition
Hydrophobic amino acids: Amino acids found buried in the interior of proteins Hydrophilic amino acids: Amino acids found on the surfaces of proteins
Select the statements that correctly describe the digestion of proteins in the body.
In the small intestine, enzymes degrade proteins and peptides into amino acids that can be absorbed. In the stomach, the enzyme pepsin hydrolyzes some of the peptide bonds of the protein, creating smaller peptides.
When the temperature of a protein increases, at first the rate of molecular movement ______. Eventually, the weaker interactions that maintain the protein structure are ______.
Increase, disrupted
Almost all of the α-amino acids isolated from proteins in nature are members of the -------family.
L
What stereoisomer(s) of amino acids predominantly exist(s) in nature?
L-amino acids
Select all the statements that correctly describe the effect of pH on protein structure.
Large changes in pH affect the charge of the protein and interfere with the salt bridges and hydrogen bonds that stabilize the tertiary structure. The charged R groups on the surface of the protein interact with ions and water molecules to keep the protein in solution.
The Fischer projection of an L-amino acid has the -NH3+ group on the------- side of the diagram when the carboxyl group is drawn at the top and the R group at the bottom.
Left
A protein is a ------formed by joining amino acid subunits together using------ bonds.
Linear polymers, Peptide bond
Identify which of the following amino acids are positively charged at a pH of 7.
Lysine Arginine Histidine
When egg whites are whipped into a stiff meringue, the proteins in the egg are denatured due to ______ stress.
Mechanical
What is the major property of fibrous proteins that contain coiled α-helices?
Mechanical strength
Select the statement that correctly describes complete and incomplete proteins.
Most high-protein vegetables do not have all the essential amino acids needed for daily intake.
What accounts for efficient transfer of oxygen from the bloodstream to the cells of the body via myoglobin?
Myoglobin has a great attraction for oxygen.
Match the term with its definition
N-terminal amino acid: Amino acid in a peptide with a free amino group C-terminal amino acid: Amino acid in a peptide with a free carboxyl group
Hydrophobic amino acids have side chains that are _____ and prefer to remain buried in the protein structure, isolated from water. Hydrophilic amino acids have side chains that are _____ and are attracted to water molecules.
Nonpolar, polar
How do polar organic solvents disrupt protein structures?
Polar organic solvents disrupt the hydrogen bonds within a protein. The nonpolar regions of an organic solvent interfere with hydrophobic interactions in the interior of a protein.
Denaturation of a protein causes the protein to lose its characteristic three-dimensional shape but does not affect the________structure.
Primary
Match the level of protein structure with its correct description.
Primary structure: The particular sequence of amino acids that are joined together by peptide bonds Secondary structure: The three-dimensional arrangement of localized regions of a protein. Tertiary structure: The three-dimensional shape adopted by the entire peptide chain Quaternary structure: The shape adopted when two or more folded polypeptide chains come together into one protein complex
Match the features listed below with the appropriate level of protein structure.
Primary structure: This level of structure is formed by peptide bonds joining together by amino acids. Secondary structure: This level of structure is formed by hydrogen bonds along the peptide backbone. Tertiary structure: This level of structure is stabilized by London dispersion forces, hydrogen bonds, electrostatic attractions, and disulfide bonds formed between the side chains of amino acids.
Functional proteins often involve the binding to a nonprotein group called a ______ group. For example, each subunit of hemoglobin is bound to an iron-containing heme group.
Prosthetic
Enzymes, antibodies, and antigens are all examples of ______.
Protein
Why are proteins an important class of food molecules?
Proteins are the only dietary source of nitrogen and sulfur for an organism.
Which of the following statements describe the role of a protein?
Proteins carry materials from one place to another in the body. Proteins regulate the body's metabolism. Proteins give structure and support to tissue and cells.
In some cases, the ______ structure of a functional protein involves binding to a nonprotein group known as a prosthetic group.
Quaternary
The association of several polypeptides to produce one functional protein is known as the_________ structure of the protein.
Quaternary structure
Glycoproteins frequently act as______ proteins on the cell surface, to bind to specific substrates. A glycoprotein has a______ group covalently attached to the protein.
Receptor, sugar
D-amino acids have the -NH3+ group on the -------- side in a Fischer projection with the carboxyl group drawn at the top and the R group at the bottom.
Right hand
A peptide bond is formed by reacting ______.
The amino group of one amino acid with the carboxylate group of another amino acid.
Amino acids differ from one another by ______.
The identify of the R group
What statement correctly describes the rotation of bonds and the conformations in a peptide or protein?
The number of peptide conformations is limited by the rigid peptide bond.
Which of the following statements correctly describes the primary structure of a protein?
The primary structure of a protein is the sequence of amino acids joined together by peptide bonds.
Which of the following statements correctly describes the secondary structure of a protein?
The secondary structure of a protein is the folding of the protein into regularly repeating structures.
The prefixes D and L are used to designate ______.
The spatial arrangement of the groups on the chiral center of amino acids
Which of the following statements correctly describes the tertiary structure of a protein?
The tertiary structure of a protein is the three-dimensional shape adopted by the entire polypeptide chain.
How are the names of amino acids abbreviated?
Three-letter abbreviation One-letter abbreviation
Hemoglobin is an oxygen______protein found in red blood cells, whereas myoglobin is the oxygen______protein in skeletal muscle.
Transport, storage
T/F The β-pleated sheet arrangement is favored by amino acids having small R groups like alanine, serine, and glycine.
True
Which of the following illustrates the denaturation of proteins via mechanical stress?
Whipping egg whites
What common type of secondary structure is a coiled, helical conformation?
a-helix
Human hair is an example of a(n) ______, a fibrous protein part of an array known as a microfibril.
a-keratin
Many cellular proteins are soluble in the cell cytoplasm and are usually _____.
globular proteins
The addition of ______ to proteins interferes with salt bridges and may bind to sulfhydryl groups.
heavy metals
When detergents interact with proteins, the detergents disrupt _____ interactions, causing the protein chain to unfold.
hydrophobic
