/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 18 Amino acids are taken up by anim... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 12: Problem 18

Amino acids are taken up by animal cells using a symport in the plasma membrane. What is the most likely ion whose electrochemical gradient drives the import? Is ATP consumed in the process? If \(s o,\) how?

Short Answer

Expert verified
Sodium ions ( Na^+ ) drive the symport, and ATP is consumed indirectly by the sodium-potassium pump.

Step by step solution

01

Understanding the Symport Mechanism

In animal cells, the symport mechanism works by using the electrochemical gradient of a specific ion to drive the uptake of other molecules, such as amino acids, into the cell.
02

Identifying the Ion Involved

Animal cells commonly use sodium ions ( ^+ ) to drive symport processes. The electrochemical gradient of sodium, maintained by the sodium-potassium pump, is often harnessed to transport other molecules against their concentration gradients.
03

Role of ATP in Maintaining Gradients

The sodium-potassium pump actively transports 3 Na^+ ions out of the cell and 2 K^+ ions into the cell, maintaining the sodium gradient. This process directly consumes ATP, but the symport itself does not consume ATP at the moment of amino acid transport.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Electrochemical Gradient
The electrochemical gradient is a fundamental concept in cell biology that refers to the combined effect of a concentration gradient and an electrical gradient. This gradient occurs across a cell's membrane and is essential for various cellular processes. When certain ions, such as sodium ions (Na鈦�), are distributed unequally across a membrane, a potential energy source is created. This energy can be used to power the transport of other molecules into the cell. An electrochemical gradient involves:
  • Concentration Gradient: The difference in the concentration of ions across the membrane.
  • Electrical Gradient: The difference in charge across the membrane.
These two gradients combined form a powerful driving force. This can be used by cells to facilitate the transport of nutrients and waste. In the context of amino acid transport, the electrochemical gradient of sodium helps bring these crucial building blocks into the cell efficiently.
Sodium-Potassium Pump
The sodium-potassium pump is a vital membrane protein in animal cells responsible for maintaining the balance of sodium and potassium ions. This pump moves sodium ions out of the cell while bringing potassium ions into the cell, crucial for several cellular functions. Here's how it works:
  • It actively transports 3 Na鈦� ions out of the cell.
  • It then brings 2 K鈦� ions into the cell.
  • This activity requires energy from ATP, converting ATP into ADP and a phosphate group.
The process helps maintain a lower concentration of sodium ions inside compared to outside the cell and a higher concentration of potassium ions. This ion gradient is critical for the electrochemical gradient used in symport mechanisms. Without this pump, the crucial processes that depend on these gradients, like nerve impulse transmission and muscle contraction, would be impaired.
Amino Acid Transport
Amino acid transport is crucial for acellular function, providing cells with the necessary components for protein synthesis and various metabolic processes. In animal cells, this transport often occurs via a symport mechanism. This means that amino acids and sodium ions are transported into the cell together, using the sodium electrochemical gradient. The process is efficient because:
  • It does not require direct ATP consumption for the symport itself.
  • Instead, it harnesses the energy from the sodium gradient maintained by the sodium-potassium pump.
This method of transport allows cells to efficiently intake amino acids, even if their concentration outside the cell is relatively low compared to the inside. By using existing gradients, cells conserve energy while still actively controlling what enters and exits, maintaining the balance necessary for optimal cellular function.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

In the disease myasthenia gravis, the human body makes-by mistakeantibodies to its own acetylcholine receptor molecules. These antibodies bind to and inactivate acetylcholine receptors on the plasma membrane of muscle cells. The disease leads to a devastating progressive weakening of the muscles of people affected. Early on, they may have difficulty opening their eyelids, for example, and, in an animal model of the disease, rabbits have difficulty holding their ears up. As the disease progresses, most muscles weaken, and people with myasthenia gravis have difficulty speaking and swallowing. Eventually, impaired breathing can cause death. Explain which step of muscle function is affected.

One thousand \(\mathrm{Ca}^{2+}\) channels open in the plasma membrane of a cell that is \(1000 \mu \mathrm{m}^{3}\) in size and has a cytosolic \(\mathrm{Ca}^{2+}\) concentration of \(100 \mathrm{nM}\). For how long would the channels need to stay open in order for the cytosolic \(\mathrm{Ca}^{2+}\) concentration to rise to \(5 \mu \mathrm{M} ?\) There is virtually unlimited \(\mathrm{Ca}^{2+}\) available in the outside medium (the extracellular \(\mathrm{Ca}^{2+}\) concentration in which most animal cells live is a few millimolar), and each channel passes \(10^{6} \mathrm{Ca}^{2+}\) ions per second.

Name at least one similarity and at least one difference between the following (it may help to review the definitions of the terms using the Glossary): A. Symport and antiport B. Active transport and passive transport C. Membrane potential and electrochemical gradient D. Pump and transporter E. Axon and telephone wire F. Solute and ion

List the following compounds in order of decreasing lipidbilayer permeability: RNA, \(\mathrm{Ca}^{2+}\), glucose, ethanol, \(\mathrm{N}_{2}\), water

Acetylcholine-gated cation channels do not discriminate between \(\mathrm{Na}^{+}, \mathrm{K}^{+},\) and \(\mathrm{Ca}^{2+}\) ions, allowing all to pass through them freely. So why is it that when acetylcholine binds to this protein in the plasma membrane of muscle cells, the channel opens and there is a large net influx of primarily \(\mathrm{Na}^{+}\) ions?
See all solutions

Recommended explanations on Biology Textbooks

Genetic Information

Read Explanation

Plant Biology

Read Explanation

Ecological Levels

Read Explanation

Biological Molecules

Read Explanation

Microbiology

Read Explanation

Cell Communication

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.