Cell biologyLesson 1 of 3 in the course Mitochondria and cellular respiration

Mitochondrial Structure, Bioenergetics, Signaling, Genetics, and Disease

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

A mitochondrion is enclosed by an outer membrane and an inner membrane, both made from phospholipid bilayers and proteins. The membranes have different compositions and properties, creating distinct environments inside the organelle.

A mitochondrion that has had its outer membrane removed is called a mitoplast.

The outer membrane contains porins, including the voltage-dependent anion channel (VDAC), which allows many small ions and metabolites to move between the cytosol and intermembrane space. Larger proteins generally require targeting signals and specialized import machinery to enter the mitochondrion. The intermembrane space contains proteins such as cytochrome c, which participates in electron transfer and can also signal cell death when released into the cytosol.

All flashcards

What are cristae?
Cristae are folds of the inner mitochondrial membrane. They increase the membrane's surface area, supporting the processes involved in respiration and ATP production.
What is the mitochondrial matrix?
The matrix is the fluid-filled space enclosed by the inner membrane. It contains metabolic enzymes, mitochondrial DNA, ribosomes, and transfer RNAs.
What is a mitoplast?
A mitoplast is a mitochondrion from which the outer membrane has been removed.
What role does VDAC play?
VDAC is a pore-forming channel in the outer membrane that serves as a major route for the movement of nucleotides, ions, and metabolites between the cytosol and intermembrane space.
Why do mitochondria differ among cell types?
Different cells have different energy demands and specialized roles. As a result, their mitochondria can vary in number, size, shape, crista density, and location.

Quiz questions

  1. When cytochrome c is released from mitochondria into the cytosol, what can it help initiate?Answer: Apoptosome formation during programmed cell death.
  2. What is one key function of mitochondria-associated ER membranes (MAMs)?Answer: They support calcium transfer and lipid exchange between the ER and mitochondria.
  3. How can calcium entering the mitochondrial matrix affect energy metabolism?Answer: It can activate enzymes in the citric acid cycle.
  4. Which observation supports the endosymbiotic origin of mitochondria?Answer: Mitochondria have bacterial-like ribosomes and divide by fission.
  5. What can human mitochondrial DNA help researchers trace, given its usual inheritance pattern?Answer: Maternal lineages and aspects of population history.

Based on the Wikipedia article Mitochondria, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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