Cellular Functions Explained: The Basics of Chapter 3

The cell membrane is a complex structure made of phospholipids arranged in a bilayer.Each phospholipid has a hydrophilic head that loves water, and hydrophobic tails that avoid water.The membrane is selectively permeable, meaning it allows some molecules to pass through while blocking others.Small molecules like water and oxygen can pass directly through the membrane.While larger molecules or charged particles are blocked.Passive transport requires no energy and moves molecules from high to low concentration.Like tea diffusing in water, molecules naturally move from areas of high concentration to low concentration.This process continues until equilibrium is reached.Active transport, unlike passive transport, requires energy in the form of ATP.Transport proteins use ATP energy to move molecules against their concentration gradient.This allows cells to maintain necessary concentrations of important molecules, even when they must move against the natural gradient.This control over molecular movement is essential for maintaining cellular function and homeostasis.Inside the mitochondria, cells break down glucose to produce ATP through a complex series of chemical reactions.The process begins with glycolysis, which occurs in the cell's cytoplasm.During glycolysis, one glucose molecule is split into two pyruvate molecules, producing a net gain of two ATP.The pyruvate molecules then enter the Krebs cycle, which occurs in the mitochondrial matrix.The Krebs cycle is a series of chemical reactions that generate more ATP and produce high-energy electron carriers.Finally, these high-energy electrons enter the electron transport chain in the inner mitochondrial membrane.As electrons move through the protein complexes, their energy is used to pump hydrogen ions and ultimately produce most of the cell's ATP.Let's summarize the ATP production from each stage of cellular respiration.In total, one glucose molecule can yield up to 38 ATP molecules through the complete process of cellular respiration.Cells communicate through an intricate system of chemical signals and receptor proteins.The signaling cell releases chemical messengers, such as hormones or neurotransmitters.Target cells have specific receptor proteins on their surface that recognize these signals.When chemical signals reach the target cell, they bind to these receptors, triggering a response.This binding initiates a cascade of molecular events inside the cell.The cell can respond in various ways, including activating genes, producing proteins, changing its metabolism, or initiating cell division.This communication system helps maintain homeostasis through feedback loops.Let's review the key points about cell communication.Thanks for learning about cell communication with Spark.E!