Mitochondria and Cellular Energy

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Questions and Answers

What is the main function of NADH in the mitochondrion?

To provide electrons for the electron transport chain (correct)

To directly consume oxygen

To oxidize acetyl groups in the matrix

To catalyze the citric acid cycle

Which structural feature of the inner mitochondrial membrane increases its surface area?

Outer membrane

Matrix

Porins

Cristae (correct)

In what form is energy primarily stored during biological oxidation in mitochondria?

As heat

As water

As ATP (correct)

As NADH

Which of the following statements is true regarding the citric acid cycle?

It produces CO2 and NADH in the matrix Signup and view all the answers

What role do cristae play in mitochondrial function?

Facilitate greater ATP production Signup and view all the answers

What triggers the energetically favorable reaction of H2 and O2 to form water in mitochondria?

Passage of electrons through carriers Signup and view all the answers

How does the mitochondrial enzyme activity vary?

It is determined by cell type Signup and view all the answers

What happens during the process of oxidative phosphorylation?

ATP is synthesized from ADP and inorganic phosphate Signup and view all the answers

What drives the flow of H+ through the ATP synthase in mitochondria?

Electrochemical proton gradient Signup and view all the answers

How many net ATP are produced from one molecule of glucose during cellular respiration?

30-32 net ATP Signup and view all the answers

In which part of cellular respiration is NADPH produced?

During the metabolism of citrate in the cytosol Signup and view all the answers

What role do bacteria play in chemiosmotic mechanisms?

They first developed chemiosmotic mechanisms. Signup and view all the answers

What is the main purpose of mitochondria in cell metabolism?

To produce ATP for cellular needs Signup and view all the answers

Which of the following describes strict anaerobes in terms of energy production?

They only use glycolysis for energy. Signup and view all the answers

Which compound is actively transported from the mitochondrion to the cytosol for NADPH production?

Citrate Signup and view all the answers

What type of pathway does ATP synthase create across the inner mitochondrial membrane?

Hydrophilic pathway Signup and view all the answers

What main function do mitochondria serve in eukaryotic cells?

They produce most ATP through specialized membranes. Signup and view all the answers

What is the first electron carrier in the electron-transport chain of mitochondria?

NAD+ Signup and view all the answers

Which process describes the flow of protons through ATP synthase?

Facilitated diffusion of H+ down its gradient. Signup and view all the answers

What establishes the electrochemical proton gradient in mitochondria?

Electron transfer that pumps protons across the membrane. Signup and view all the answers

What is the primary function of NADH in cellular respiration?

To transport electrons to the inner mitochondrial membrane Signup and view all the answers

What is chemiosmotic coupling primarily responsible for?

Synthesis of ATP from ADP and inorganic phosphate. Signup and view all the answers

Which statement is true about the endosymbiotic theory?

Eukaryotic cells gained the ability for aerobic respiration and photosynthesis Signup and view all the answers

Which statement accurately describes the role of NAD+ in mitochondria?

NAD+ takes up electrons and protons to become NADH. Signup and view all the answers

What role do porins play in the outer membrane of the mitochondrion?

They form channels allowing small molecules to pass into the intermembrane space Signup and view all the answers

Why is the plasma membrane primarily reserved for transport processes in eukaryotic cells?

Most ATP is produced in mitochondria, not the plasma membrane. Signup and view all the answers

What best describes the function of the electron-transport chain in mitochondria?

It facilitates the transfer of electrons to produce an ATP gradient. Signup and view all the answers

Which compartment of the mitochondrion contains enzymes for the citric acid cycle?

Matrix Signup and view all the answers

What is a primary difference between mitochondrial DNA (mtDNA) and chloroplast DNA (cpDNA)?

mtDNA is smaller than cpDNA Signup and view all the answers

What role do the electron carriers play in the electron transport chain?

They assist in oxidation-reduction reactions by guiding electrons. Signup and view all the answers

Which process explains how lung bacteria became mitochondria in eukaryotic cells?

Endosymbiotic theory Signup and view all the answers

What is the main function of ATP synthase in oxidative phosphorylation?

To regenerate ATP from ADP using a proton gradient. Signup and view all the answers

How do electrons transfer through the electron transport chain?

By moving from a high energy state to a low energy state Signup and view all the answers

What are the two consequences of H+ movement across the inner mitochondrial membrane?

Creation of a pH gradient and a voltage gradient. Signup and view all the answers

What are the two separate compartments created by the mitochondrion's membranes?

Intermembrane space and mitochondrial matrix Signup and view all the answers

How does the electrochemical proton gradient influence ATP synthesis?

It provides energy for ATP synthase to directly synthesize ATP. Signup and view all the answers

What is the primary function of the protein complexes in the respiratory chain?

To couple electron transfer with H+ movement. Signup and view all the answers

Which statement accurately describes the voltage gradient generated by H+ movement?

It pulls + ions into the matrix while pushing – ions out. Signup and view all the answers

Which of the following accurately represents the relationship between pH and the location of H+ ions?

The matrix has a higher pH compared to the cytosol and intermembrane space. Signup and view all the answers

What drives the pumping of H+ across the inner membrane during oxidative phosphorylation?

The flow of electrons through the electron transport chain. Signup and view all the answers

What is the primary role of the electron transport chain in bacteria?

To establish a proton motive force for ATP synthesis Signup and view all the answers

In some bacteria, how does ATP synthase utilize ATP produced by glycolysis?

To pump H+ ions and create a proton gradient Signup and view all the answers

Which of the following statements is true regarding protons and bacterially maintained gradients?

They help facilitate active transport of nutrients into the bacterium. Signup and view all the answers

What is NOT a characteristic of mitochondria's outer membrane?

Associated with energy production directly Signup and view all the answers

Where is NADH primarily produced within the mitochondria?

Matrix Signup and view all the answers

Which location within the mitochondria contains the respiratory chain?

Crista membrane of the inner mitochondrial membrane Signup and view all the answers

What is a function of the Na+-H+ antiporter in bacteria?

To pump H+ in exchange for Na+ Signup and view all the answers

Which of the following is true about the electrochemical potential for H+ in the intermembrane space?

It is the same as in the cytoplasm. Signup and view all the answers

Study Notes

Mitochondria

Mitochondria are organelles found in eukaryotic cells.
They are responsible for producing most of the ATP (adenosine triphosphate) in the cell.
Mitochondria have a double membrane.
The outer membrane is permeable to small molecules.
The inner membrane has folds called cristae, increasing its surface area.
The fluid-filled space within the inner membrane is the matrix.
The intermembrane space is between the inner and outer membranes.

Life Requires Energy

ATP (adenosine triphosphate) has high-energy bonds.
Cells use ATP energy for various functions
- Synthesizing cellular molecules
- Cellular movements
- Transport against concentration gradients
- Generating electric potentials across membranes
Organisms obtain energy from light (photosynthesis) or high-energy compounds (respiration).

Prokaryotes and Eukaryotes

Prokaryotes produce ATP using their plasma membrane.
Eukaryotes produce most of their ATP in specialized organelles called mitochondria.

Chemiosmotic Coupling

The process of producing ATP occurs in two stages.
- Stage 1 involves transferring high-energy electrons through electron carriers in a membrane, releasing energy to pump protons (H+) across the membrane. This builds an electrochemical proton gradient.
- Stage 2 involves H+ flowing back down its electrochemical gradient through a protein called ATP synthase, driving ATP synthesis from ADP and inorganic phosphate.

Oxidative Phosphorylation

Oxidative phosphorylation is the primary process for ATP generation in mitochondria.
Electrons from food molecules are transferred to the electron transport chain.
The electron transport chain releases energy to pump protons, creating an electrochemical gradient.
ATP synthase uses the energy of the H+ gradient to produce ATP.

Endosymbiotic Theory

Mitochondria and chloroplasts arose from free-living bacteria.
These bacteria were engulfed by larger cells, forming a symbiotic relationship.
Over time, the bacteria lost their ability to function independently.
Evidence supports the idea that these organelles evolved separately from the host cell.

Mitochondrial Structure

Mitochondria have an outer and inner membrane.
The inner membrane is folded into cristae, increasing surface area.
The matrix is the space enclosed by the inner membrane.
The intermembrane space lies between the two membranes.

Mitochondrial function

Mitochondria are responsible for cellular respiration.
Cellular respiration converts energy from food into ATP for cell use.
They produce chemical compounds that are used for energy production and other cellular processes.

Mitochondrial DNA (mtDNA)

mtDNA exists as a double-stranded circular DNA.
It is present in many copies in a single mitochondrion.
It is smaller than chloroplast DNA (cpDNA).

Chloroplast DNA (cpDNA)

cpDNA is double-stranded circular DNA.
It is smaller than mitochondrial DNA (mtDNA).
Genes in cpDNA encode products involved in photosynthesis and translation.

ATP Yield

Glycolysis produces 2 net ATP.
The citric acid cycle produces 2 ATP.
Oxidative phosphorylation produces 30 - 32 ATP per glucose molecule.

Other Mitochondrial Roles

Mitochondria play critical roles in cell metabolism, beyond ATP production.
They use amino acids as fuel during starvation.
They supply the cytosol with reducing power (NADPH), used in biosynthesis.
They also buffer the redox potential in the cytosol.
Bacteria use chemiosmosis, and pumps H+ out of the cell.
The H+ gradient is used in various bacterial processes.

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Description

Explore the fascinating world of mitochondria and their critical role in energy production within eukaryotic cells. This quiz covers the structure of mitochondria, the function of ATP, and the differences between prokaryotic and eukaryotic ATP production. Test your knowledge on how life requires energy!