Mitochondrial Function and Membrane Permeability

Questions and Answers

What will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface?

The surface area will increase.

There will be no effect.

Mitochondria will become more efficient.

Mitochondria will become less efficient. (correct)

What will most likely result from a loss of ion pump function in the cell's lysosomes?

Hydrolytic enzymes will be activated.

Internal pH of lysosomes will increase. (correct)

Lysosomes will become more acidic.

Food digestion will not be affected.

What effect does increasing the permeability of mitochondrial membranes to large molecules have?

ATP production will decrease. (correct)

No change in ATP production.

Controlled chemical reactions will increase.

ATP production will increase.

What will happen if there is no energy supply for the active transport of hydrogen ions through a membrane protein?

H^+ ions will stop moving. Signup and view all the answers

What happens to water transport across the cell membrane if the aquaporin ceases to function?

Water molecules will still move but slower. Signup and view all the answers

What outcome will result from a loss of protein X function in the movement of sodium (Na+) and potassium (K+) ions?

Membrane potential will be disrupted. Signup and view all the answers

Which data would support the alternative hypothesis regarding aquaporins?

Cells with mutated aquaporins exhibit moderate turgor pressure. Signup and view all the answers

What observation would best support the hypothesis about the functions of plant and fungal cell walls?

Both cell walls surround the outside of the cell membrane. Signup and view all the answers

What supports the hypothesis that the new drug will exhibit simple diffusion across the plasma membrane?

The drug is a small nonpolar molecule. Signup and view all the answers

How can an investigator determine if the new membrane protein is involved in membrane transport?

By adding more proteins to the plasma membrane. Signup and view all the answers

What investigation can be used to determine when cells are in an isotonic solution?

Increase the salinity of the environment gradually. Signup and view all the answers

What should be done next to gather data needed for the scientist's objective?

Incubate samples containing 1.0 m/L of ATP at four temperatures other than 25 degrees Celsius. Signup and view all the answers

What provides evidence to best support the claim that a particular organelle originated from a free-living prokaryotic cell?

The organelle has a double membrane. Signup and view all the answers

Which statement best supports the claim that certain organelles evolved from free-living prokaryotic cells?

Some organelles contain their own DNA similar to prokaryotic DNA. Signup and view all the answers

What observation best supports the model of the endosymbiont theory regarding mitochondria?

Mitochondria and some prokaryotes share similar metabolic reactions that produce ATP. Signup and view all the answers

Which areas are described as polar in a membrane model?

Areas 1 and 3. Signup and view all the answers

What explains the orientation of the phospholipid molecules in a plasma membrane model?

Hydrophilic phosphate groups are attracted to the aqueous internal and external environments. Signup and view all the answers

Why is correct protein folding critical in transmembrane proteins?

Interactions of hydrophobic and hydrophilic amino acids anchor the protein in the membrane. Signup and view all the answers

Study Notes

Mitochondrial Function and Efficiency

Changes in the shape of mitochondrial inner membranes impact efficiency; a smooth surface reduces surface area and efficiency.
Loss of ion pump function in lysosomes leads to increased internal pH, hindering hydrolytic enzyme activation and digestion processes.

Membrane Permeability and Transport

Increased permeability of mitochondrial membranes to large molecules decreases ATP production due to uncontrolled reactions.
Active transport of hydrogen ions ceases without energy supply, stopping H^+ ions from moving through protein channels.
Aquaporin failure results in slower water transport across cell membranes, but movement still occurs.

Membrane Potential and Ion Movement

Loss of specific protein functions disrupts membrane potential, leading to increased K+ concentration inside the cell.
Mutations in aquaporins lead to moderate turgor pressure in hypertonic conditions.

Cell Wall Functions in Plants and Fungi

Cell walls of plants (cellulose) and fungi (chitin) support the hypothesis that they provide distinct yet similar functions across different cell types.

Drug Transport Mechanisms

A small nonpolar molecule can passively diffuse across plasma membranes, supporting the hypothesis of simple diffusion for the drug in question.
Testing new membrane proteins requires adding proteins and measuring particle movement rates to identify channel protein functions.

Osmoregulation in Freshwater Organisms

Contractile vacuoles in freshwater organisms help manage water influx; experiments can determine isotonic conditions by adjusting salinity until minimal ATP usage is observed.

Investigative Procedures

Incubating ATP samples at various temperatures will aid data collection for scientific experiments.
Presence of a double membrane supports claims of organelle evolution from free-living prokaryotes.

Evolutionary Evidence of Organelles

Certain organelles possess DNA more similar to prokaryotes than the eukaryotic nucleus, indicating their evolutionary origins.
Mitochondria and some prokaryotes have analogous metabolic functions that contribute to ATP production, supporting the endosymbiont theory.

Structural Features of Membrane Components

Polar areas in membrane models align with water molecules, highlighting the interaction between membrane components and their aqueous environment.
Phospholipid orientation is driven by hydrophilic phosphate groups being attracted to both internal and external aqueous environments.
Proper folding of transmembrane proteins is crucial due to hydrophobic and hydrophilic interactions that anchor them within the membrane.

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Description

Explore critical aspects of mitochondrial function, membrane permeability, and ion movement in cells. This quiz covers changes in membrane efficiency, impacts on ATP production, and transport mechanisms, especially in conditions affecting aquaporins and lysosomes. Understand how these factors contribute to cell health and efficiency.