Active vs. Passive Transport: Compare and Contrast
Updated: November 17, 2024
Summary
Cells maintain internal balance through dynamic homeostasis, adjusting substances like glucose, water, oxygen, and ions. Processes like diffusion move particles from high to low concentration, with small molecules passing through the membrane easily. Facilitated diffusion uses channel proteins for larger molecules, while active transport requires ATP and can move particles against their concentration gradients. Bulk transport, like endocytosis and exocytosis, moves many molecules at once and is crucial for functions like neurotransmitter communication between neurons.
Introduction to Cell Homeostasis
Cells maintain a specific internal environment by adjusting various substances such as glucose, water, oxygen, and ions. This process is known as dynamic homeostasis and involves feedback mechanisms to regulate balance.
Passive Transport: Diffusion
Diffusion is the movement of particles from areas of high concentration to low concentration. Small and non-polar molecules can pass through the membrane without protein channels or ATP usage.
Passive Transport: Facilitated Diffusion
Facilitated diffusion involves the use of channel proteins to allow the passage of larger or polar molecules like water through the membrane. It still follows the concentration gradient without requiring ATP.
Active Transport
Active transport requires ATP input and uses carrier proteins to move molecules across the membrane, including against their concentration gradients. The process can pump particles from low to high concentration, unlike passive transport.
Bulk Transport: Endocytosis and Exocytosis
Bulk transport involves moving a large number of molecules through endocytosis (into the cell) and exocytosis (out of the cell). Neurotransmitters are an example of bulk transport for communication between neurons.
FAQ
Q: What is dynamic homeostasis?
A: Dynamic homeostasis is the process by which cells maintain a specific internal environment by adjusting various substances to regulate balance through feedback mechanisms.
Q: Explain diffusion and how it works.
A: Diffusion is the movement of particles from areas of high concentration to low concentration. Small and non-polar molecules can pass through the membrane without protein channels or ATP usage.
Q: What is facilitated diffusion and how does it differ from simple diffusion?
A: Facilitated diffusion involves the use of channel proteins to allow the passage of larger or polar molecules like water through the membrane. It still follows the concentration gradient without requiring ATP, unlike active transport.
Q: Describe active transport and its energy requirements.
A: Active transport requires ATP input and uses carrier proteins to move molecules across the membrane, including against their concentration gradients. It can pump particles from low to high concentration, unlike passive transport.
Q: What is bulk transport and provide an example of its occurrence in cells?
A: Bulk transport involves moving a large number of molecules through endocytosis (into the cell) and exocytosis (out of the cell). An example of bulk transport is the use of neurotransmitters for communication between neurons.
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