Mitochondria and Peroxisomes Overview

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Questions and Answers

What process do mitochondria primarily use to convert energy derived from carbohydrates and fatty acids into ATP?

Oxidative phosphorylation (correct)

Beta-oxidation

Fermentation

Glycolysis

Which of the following statements about mitochondrial proteins is true?

All mitochondrial proteins are synthesized within the mitochondria.

Mitochondrial proteins are synthesized on the ribosomes attached to the mitochondrial membrane.

Most mitochondrial proteins are encoded by the nuclear genome. (correct)

Mitochondrial proteins are imported as incomplete polypeptides.

What is the main function of peroxisomes in the cell?

Breakdown of fatty acids and detoxification (correct)

ATP production

Synthesis of ribosomal RNA

Storage of genetic information

What structural feature of mitochondria increases their surface area?

Cristae Signup and view all the answers

Which type of genetic material is found within mitochondria?

Mitochondrial DNA including tRNA and rRNA Signup and view all the answers

Which of the following best describes how proteins are directed to mitochondria?

They contain specific directing signals for incorporation. Signup and view all the answers

What is the main compartment of the mitochondria where oxidative metabolism takes place?

Matrix Signup and view all the answers

What characteristic of mitochondria contributes to their dynamic nature?

They can undergo both fusion and fission. Signup and view all the answers

What is the role of mobile chaperones Tim9-Tim10 in mitochondrial protein transport?

To escort proteins to the Tim22 translocase Signup and view all the answers

Which complex is responsible for the insertion of outer membrane proteins into the mitochondria?

SAM complex Signup and view all the answers

How are multipass transmembrane proteins typically targeted to the inner mitochondrial membrane?

By internal signals Signup and view all the answers

What type of proteins are predominantly found in the outer mitochondrial membrane?

Barrel β proteins Signup and view all the answers

Where are the majority of lipids found in mitochondrial membranes synthesized?

In the cytosol Signup and view all the answers

Which process is responsible for synthesizing cardiolipin in mitochondria?

Synthesis from phosphatidylserine Signup and view all the answers

What function do the chaperones serve after proteins exit the Tom complex?

Assist in insertion into the outer membrane Signup and view all the answers

What characteristic do many of the inner membrane proteins that do not contain presequences share?

They possess multiple internal signals Signup and view all the answers

What is a potential method to avoid transmitting mitochondrial diseases to offspring?

Mitochondrial replacement Signup and view all the answers

How many proteins are contained within mammalian mitochondria that are encoded by nuclear genes?

1,500 Signup and view all the answers

What is the role of Tom complex in mitochondrial protein transport?

It directs translocation through the outer mitochondrial membrane. Signup and view all the answers

Which sequence primarily directs proteins to mitochondrial import?

Aminoterminal presequences Signup and view all the answers

What must proteins do to be directed to the mitochondrial matrix?

Cross the outer and inner mitochondrial membranes. Signup and view all the answers

What is the function of Tim23 in mitochondrial protein transport?

It assists in crossing the inner mitochondrial membrane. Signup and view all the answers

What establishes the electrochemical potential that aids in mitochondrial protein transport?

Electron transport across the inner membrane Signup and view all the answers

Which of the following techniques involves manipulation or destruction of embryos?

Mitochondrial replacement techniques Signup and view all the answers

Study Notes

Mitochondria

Mitochondria are responsible for generating most cellular energy from the breakdown of lipids and carbohydrates.
They are found in all cells.
Mitochondria have a double membrane structure: an outer and inner membrane.
The inner membrane folds into cristae, increasing surface area available for chemical reactions.
The matrix contains the mitochondrial genetic system plus enzymes for key oxidative metabolic reactions.
The oxidative breakdown of glucose and fatty acids produces ATP.
Mitochondrial proteins are coded and translated by the nuclear genome, then directed to organelles.
Mitochondria contain their own DNA (mtDNA) that encodes tRNA, rRNA, and some mitochondrial proteins.
Mitochondrial membrane structure is maintained by fusion and fission processes.

Peroxisomes

Peroxisomes are small organelles found in all eukaryotic cells.
They are surrounded by a membrane.
These organelles contain enzymes for varied metabolic pathways, including fatty acid breakdown and photorespiration.
Peroxisomes contain enzymes to produce hydrogen peroxide, which is then broken down by catalase.
They play a role in the oxidation of fatty acids in the cellular metabolic processes.
Peroxisomes are involved in lipid synthesis (e.g., plasmalogens)
Peroxisomes have no genome of their own.
Peroxisomal proteins are synthesized on cytosolic ribosomes, but some are from the ER.
Many peroxisomal proteins contain specific targeting signals that allow specific targeting.
Peroxisomes can form through budding or by division from existing peroxisomes.

Mitochondrial and Peroxisomal Protein Import and Formation

Proteins destined for mitochondria and peroxisomes are usually synthesized in the cytosol, then imported into their respective target organelles.
Proteins destined for the mitochondria and peroxisomes are complete polypeptide chains.
Transport into these organelles is through a series of proteins that form import machinery.
The inner membrane of mitochondria contains the import machinery (TOM/TIM) to transport proteins inside

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Description

Explore the essential roles of mitochondria and peroxisomes in cellular metabolism. This quiz covers their structures, functions, and the metabolic processes they facilitate. Test your knowledge of these vital organelles found in eukaryotic cells.