High School Biology : DNA, RNA, and Proteins
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Example Questions
Example Question #511 : High School Biology
What is one of the main function of the protein hemoglobin?
To transport oxygen from the lungs to the tissues
To store oxygen for later use
None of these answers
To recognize and fight infections
To transport carbon dioxide from the lungs to the tissues
To transport oxygen from the lungs to the tissues
Hemoglobin is a protein found in red blood cells. It has a high affinity to bind to oxygen, carbon dioxide, and carbon monoxide. In the lungs, where oxygen concentrations are high, hemoglobin will bind to oxygen molecules and carry them through the blood to deliver to the cells of the body. Oxygen can then be used by these cells to gain energy through oxidative phosphorylation and the electron transport chain, which require oxygen as an electron receptor.
Though hemoglobin can bind carbon dioxide, most carbon dioxide waste is dissolved in the blood in the form of bicarbonate and carbonic acid. Hemoglobin's high affinity for carbon monoxide means that, when the gas is present in excess, it can block the binding sites for oxygen. This is the reason for the toxicity associated with carbon monoxide poisoning.
Example Question #61 : Proteins
Which of the following describes a function of proteins?
Structural elements
Cell signaling
All of these answers are correct
Receptors
Enzymes
All of these answers are correct
Proteins have the most diverse functions in biological systems. Their remarkable diversity in function is due to their diversity in structure. Structural proteins, such as tubulin and collagen, have a fibrous structure that aids their function. Enzymes have active sites that allow them to bind specific molecules (substrates) and enact a conformational change to facilitate chemical reactions. Signaling proteins include several types of hormones, known as peptide hormones. Protein receptors are commonly found embedded in the cell membrane and contain active sites to bind substrates, hydrophilic regions to interact with the cell environment and extracellular space, and hydrophobic regions to interact within the lipid bilayer.
Example Question #1 : Understanding Specific Protein Functions
Which type of protein is found in hair?
Fibrin
Collagen
Myosin
Trypsin
Keratin
Keratin
Keratin is a fibrous protein found in hair, nails, and the epidermis of skin. Myosin is one of the major proteins of muscle. Trypsin is an enzyme in the small intestine that helps digest proteins. Collagen is a fibrous protein found in connective tissue, such as bone and cartilage. Fibrin is a clotting protein found in the blood in response to injury.
Example Question #2 : Understanding Specific Protein Functions
The proteins collagen and keratin perform what function in the body?
Provide structure
Defend against foreign particles
Act as catalysts
Relay signals
Facilitate movement
Provide structure
Collagen in skin and keratin in hair and nails provide the body with structure. Actin and myosin are found in muscle and facilitate movement. Antibodies defend the body against microbes. Numerous enzymatic proteins, such as pepsin and lipase, act as catalysts. Peptide hormones, such as insulin and oxytocin, help relay signals in the body.
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