Cell Physiology Flashcards
Describe the function of a receptor protein found in the cell membrane.
Receptor proteins bind to specific extracellular molecules, called ligands, such as hormones or neurotransmitters. This binding triggers a change in the cell, initiating a signal transduction pathway that leads to a specific cellular response.
Explain the difference between channel-mediated and carrier-mediated facilitated diffusion.
Channel-mediated facilitated diffusion involves ions moving through a protein channel in the membrane down their concentration gradient without binding to the protein. In contrast, carrier-mediated facilitated diffusion requires the solute to bind to a specific carrier protein, which then undergoes a conformational change to transport the solute across the membrane.
What is osmotic pressure, and how is it affected by solute concentration?
Osmotic pressure is the pressure required to prevent the movement of water across a semipermeable membrane due to osmosis. It is directly proportional to the solute concentration of a solution; the higher the solute concentration, the higher the osmotic pressure.
Differentiate between a hypertonic solution and a hypotonic solution, and explain how each affects a cell.
A hypertonic solution has a higher solute concentration (lower water concentration) than the inside of the cell, causing the cell to lose water and shrink. A hypotonic solution has a lower solute concentration (higher water concentration) than the inside of the cell, causing the cell to gain water and swell, potentially leading to lysis.
Explain the process of primary active transport and give an example.
Primary active transport uses ATP directly to move substances against their concentration gradient. An example is the Na+/K+-ATPase pump, which uses ATP to pump 3 sodium ions out of the cell and 2 potassium ions into the cell.
Describe the two types of endocytosis.
The two types of endocytosis are phagocytosis and pinocytosis. Phagocytosis is the process of engulfing large particles or cells, often referred to as “cell eating”. Pinocytosis is the process of taking in fluids and dissolved substances, often referred to as “cell drinking”.
Outline the two main steps of protein synthesis.
The two main steps of protein synthesis are transcription and translation. Transcription involves copying a DNA template into messenger RNA (mRNA). Translation involves using mRNA to assemble amino acids into a polypeptide chain, forming a protein.
What is the role of the Golgi complex in protein synthesis?
The Golgi complex is the site of further processing of proteins by carbohydrate and lipid modifications, so that the proteins can be packaged into vesicles and sent to their destinations.
Explain how enzymes catalyze biochemical reactions.
Enzymes increase the rate of biochemical reactions by lowering the activation energy required for the reaction to occur. They do this by binding to the substrates and facilitating the formation of the transition state.
Describe the three stages of cellular respiration, noting which part is aerobic.
The three stages of cellular respiration are glycolysis, the Krebs Cycle, and the Electron Transport Chain. Glycolysis occurs in the cytosol and is anaerobic, while the Krebs Cycle and Electron Transport Chain occur in the mitochondria and are aerobic.
