In the context of phosphorylation, what is a kinase?

• A. A molecule that removes phosphate groups from proteins
• B. A protein that binds to DNA to regulate transcription
• C. An enzyme that adds phosphate groups to proteins
• D. A lipid that forms the cell membrane

Answer: (C)

Verified step by step guidance

1. Understand the role of phosphorylation in cellular processes: Phosphorylation is a biochemical process that involves the addition of a phosphate group to a molecule, often a protein, which can alter the protein's function and activity.
2. Identify the function of a kinase: A kinase is a type of enzyme that catalyzes the transfer of phosphate groups from high-energy donor molecules, like ATP, to specific substrates, usually proteins. This process is known as phosphorylation.
3. Differentiate between kinases and other enzymes: Unlike phosphatases, which remove phosphate groups, kinases specifically add phosphate groups to proteins, thereby modifying their activity, function, or location within the cell.
4. Recognize the importance of kinases in cellular signaling: Kinases play a crucial role in signal transduction pathways, where they help transmit signals by phosphorylating target proteins, leading to a cascade of cellular responses.
5. Connect the concept to broader biological processes: Kinases are involved in regulating various cellular processes, including cell growth, metabolism, and apoptosis, making them essential for maintaining cellular homeostasis and responding to external stimuli.