Question

In eukaryotes, fermentation is completed in the _____. a. nucleus c. plasma membrane b. mitochondrion d. cytoplasin

Short answer

Fermentation in eukaryotes is completed in the cytoplasm.

Step-by-step solution

Understanding the Question

The question asks us to determine where fermentation is completed in eukaryotic cells. Fermentation is an anaerobic process, meaning it does not require oxygen and must take place in a part of the cell that facilitates such a process.

Recognizing the Process

Fermentation typically occurs after glycolysis when oxygen is not available for cellular respiration. Since it's an anaerobic process, it needs to happen in a cell part that doesn't rely on oxygen.

Evaluating the Options

Assess each option: a. Nucleus - primarily for genetic material storage, not involved in energy production processes like fermentation. b. Mitochondrion - involved in aerobic respiration, unsuitable for fermentation which is anaerobic. c. Plasma membrane - associated with cell protection and transport of substances, not directly involved in fermentation. d. Cytoplasm - location for glycolysis and suitable for anaerobic processes.

Choosing the Correct Answer

The best choice based on the understanding that fermentation is an anaerobic process is 'd. cytoplasm'. Fermentation follows glycolysis which takes place in the cytoplasm, and the entire fermentation process is also completed there.

Key concepts

Anaerobic Process

The term "anaerobic" refers to processes that occur without the use of oxygen. In the context of cellular activities, anaerobic processes are crucial because they allow cells to continue generating energy even when oxygen is scarce. Cells often rely on these processes during intense activities when oxygen supply is limited.

Fermentation is a prime example of an anaerobic process. It is crucial in muscle cells during vigorous exercise when the demand for oxygen exceeds the supply. During such times, cells must adapt by switching from oxygen-dependent processes (aerobic) to anaerobic pathways such as fermentation. This ensures they can still produce energy to stay functional.

• Enables energy production without oxygen.
• Vital during high-energy demands.
• Allows survival in oxygen-limited environments.

Cytoplasm

The cytoplasm is a gel-like substance that fills the interior of the cell. It encompasses all cellular contents outside the nucleus and houses various organelles, playing a pivotal role in cellular operations and reactions.

As the site of metabolic activities, the cytoplasm is where glycolysis, the initial step in both aerobic and anaerobic respiration, occurs. This means it actively participates in pathways that either require or do not require oxygen, depending on the cell's conditions. It is the focal point for fermentation processes that follow glycolysis when oxygen isn't present.

• Site of numerous critical cellular processes.
• Hosts key pathways like glycolysis and fermentation.
• Adaptable to both aerobic and anaerobic conditions.

Glycolysis

Glycolysis is the first step in the breakdown of glucose to extract energy for cellular metabolism. It's a ten-step process that takes place in the cytoplasm of the cell, making it suitable for both aerobic and anaerobic conditions.

During glycolysis, one molecule of glucose is converted into two molecules of pyruvate, with a net gain of two molecules of ATP (adenosine triphosphate), the energy currency of the cell. Glycolysis does not require oxygen, and its products can proceed to enter either anaerobic or aerobic pathways depending on the availability of oxygen.

• Occurs in the cytoplasm.
• Produces pyruvate and ATP.
• Oxygen-independent process.

Cellular Respiration

Cellular respiration is the process by which cells convert sugars into energy, utilizing oxygen in the process. It mainly occurs in mitochondria, where it involves a series of metabolic reactions that convert biochemical energy from nutrients into ATP.

While cellular respiration includes glycolysis, the process itself is typically associated with aerobic conditions, as its subsequent steps (Krebs cycle and electron transport chain) require oxygen. This process highlights the importance of oxygen in cells, as it allows for maximal energy extraction from glucose, far greater than anaerobic pathways.

• Involves oxygen-dependent steps.
• Occurs mainly in mitochondria.
• Maximizes energy extraction from glucose.

Fermentation in Eukaryotes

In eukaryotic cells, fermentation follows glycolysis when there is a lack of adequate oxygen for aerobic respiration. It takes place in the cytoplasm and is an essential process that temporarily allows ATP production in the absence of oxygen.

Two primary types of fermentation found in eukaryotes are lactic acid fermentation and alcohol fermentation. Muscle cells, during intense exercise, often undergo lactic acid fermentation, leading to the temporary production of lactic acid. In contrast, yeast cells commonly perform alcohol fermentation, converting sugars into ethanol and carbon dioxide.

• Occurs in the cytoplasm following glycolysis.
• Enables ATP production without oxygen.
• Types include lactic acid and alcohol fermentation.