Mitochondria

What are the overall functions of mitochondria?

Energy production, respiration, and oxidative phosphorylation.

What is the role of mitochondrial DNA?

Mitochondrial DNA encodes components of the respiratory chain complexes and some ribosomal and transfer RNAs.

How are proteins imported into mitochondria?

They require specific signal sequences to be imported.

What is the role of mitochondria in apoptosis?

Mitochondria play a crucial role by releasing apoptotic factors that activate cell death pathways.

What is the primary function of the endoplasmic reticulum (ER)?

The ER is responsible for protein synthesis, folding, and modification.

What are the two types of endoplasmic reticulum?

Rough ER and Smooth ER.

What happens during oxidative phosphorylation?

ATP is synthesized through the electron transport chain using energy derived from the oxidation of nutrients.

What is apoptosis?

A form of programmed cell death that is controlled and allows for the removal of unnecessary or damaged cells.

What regulates the permeability of the mitochondrial outer membrane?

The Bcl-2 family of proteins regulates permeability by promoting or inhibiting apoptosis.

What is the endosymbiotic theory?

The theory that mitochondria originated from engulfed prokaryotic cells that became symbiotic.

What is the net ATP yield from glycolysis?

The net yield is 2 ATP molecules per glucose molecule.

Where do the citric acid cycle and oxidative phosphorylation occur?

They occur inside the mitochondria.

What is a significant feature of mitochondrial membranes?

Mitochondria have two membranes: an outer membrane and an inner membrane.

What is the primary electron carrier in cellular respiration?

NADH (Nicotinamide adenine dinucleotide) is the primary electron carrier.

What does ATP stand for?

Adenosine triphosphate.

What is the role of the Golgi apparatus in secretion?

The Golgi apparatus modifies, sorts, and packages proteins for secretion.

What are secretory vesicles?

Vesicles that transport proteins from the Golgi to the plasma membrane for secretion.

What is the function of lysosomes?

To digest and break down macromolecules and cellular debris.

What is a signal sequence?

A short peptide sequence that directs the transport of a protein to specific locations within the cell.

What process allows proteins to be secreted outside of the cell?

Exocytosis.

What leads to the conversion of pyruvate to lactate?

Anaerobic conditions where oxygen is limited.

What is the main role of mitochondrial calcium storage?

To regulate cellular processes, including energy metabolism and apoptosis.

What is programmed cell death also known as?

Apoptosis.

What is the primary function of chaperones in the ER?

To assist in the proper folding of proteins and prevent misfolding.

How do proteins end up in lysosomes?

They are tagged with mannose 6-phosphate for transport from the Golgi.

What is constitutive secretion?

Continuous and unregulated secretion of proteins.

What is regulated secretion?

Secretion of proteins in response to specific signals or stimuli.

What is the significance of the cytochrome c in mitochondria?

It plays a role in the electron transport chain and in apoptosis.

What are the components of mitochondrial DNA?

13 protein-coding genes, ribosomal RNAs, and transfer RNAs.

What happens during the electron transport chain?

Electrons are transferred through a series of complexes, driving the production of ATP.

What triggers the inner mitochondrial membrane permeabilization during apoptosis?

Opening of the permeability transition pore complex.

How are proteins modified in the ER?

Through glycosylation and folding processes facilitated by chaperones.

What are the roles of Protein Translocases TOM and TIM?

TOM (Translocase of the Outer Membrane) transports proteins across the outer membrane, while TIM (Translocase of the Inner Membrane) transports proteins across the inner membrane.

What is the typical size of mitochondrial DNA in humans?

Approximately 16 kilobases (kbp).

What is the primary difference between aerobic and anaerobic glycolysis?

Aerobic glycolysis generates more ATP by fully oxidizing pyruvate, while anaerobic glycolysis leads to lactate production with minimal ATP.

What is endocytosis?

The process by which cells take in substances by engulfing them.

What is the function of the ribosome in protein synthesis?

To synthesize proteins by translating mRNA into polypeptide chains.

What is the role of adaptins in vesicle transport?

Adaptins bind cargo receptors and coat proteins to facilitate vesicle formation.

What regulates vesicle docking and fusion with target membranes?

SNARE proteins (V-SNARE and t-SNARE) play primary roles in this process.

What is the role of cytosolic ribosomes?

To synthesize proteins that remain in the cytosol or are directed to the nucleus or mitochondria.

What term describes the breakdown of glucose to produce energy?

Glycolysis.

What are phosphoinositides?

Lipids that play an important role in signaling pathways, especially in vesicular trafficking.

How does glucose enter the glycolytic pathway?

Through phosphorylation by hexokinase, converting glucose to glucose-6-phosphate.

What happens to the electron carriers NADH and FADH2 in the electron transport chain?

They donate electrons to the transport chain, helping to generate a proton gradient.

What is vesicular traffic?

The process of transporting molecules in vesicles between various organelles.

How are membrane proteins synthesized?

On bound ribosomes of the rough ER and then inserted into the ER membrane.

What energy molecule is produced during oxidative phosphorylation?

ATP (Adenosine triphosphate).

What is the physiological role of mitochondrial Ca2+ accumulation?

To stimulate and control oxidative phosphorylation and influence cellular signaling processes.

What is a major source of mitochondrial DNA mutations?

Point mutations and deletions in the mitochondrial genome.

What enzyme dissociates at the end of endocytosis?

Hydrolytic enzymes dissociate lysosomal enzymes from their receptors.

What are the three main types of SNARE proteins involved in vesicle trafficking?

V-SNAREs, t-SNAREs, and SNAP proteins.

What is the mitochondrial permeability transition pore complex?

A complex that facilitates the release of apoptotic factors from the mitochondria.

How are secretory proteins distinguished from ER resident proteins?

Secretory proteins enter the secretory pathway, while ER resident proteins have retention signals.

What is the role of the signal recognition particle (SRP)?

To pause translation and direct ribosomes to the ER membrane.

What type of proteins are synthesized in the rough ER?

Proteins that are either secreted or targeted to membranes.

What can happen if apoptosis is insufficient?

It can lead to diseases such as cancer due to the survival of damaged cells.

What impacts the efficiency of aerobic glycolysis?

The presence of oxygen as the final electron acceptor.

What happens to proteins that cannot be properly folded in the ER?

They are degraded by ER-associated degradation (ERAD).

How is the integrity of mitochondrial membranes preserved during apoptosis?

Bcl-2 family proteins regulate membrane permeability.

What is the consequence of mitochondrial dysfunction?

Potential development of various diseases, including neurodegenerative disorders.

What is the primary role of the Golgi apparatus in glycoprotein processing?

To modify, sort, and package glycoproteins for secretion.

What is a key difference in the structure of the outer and inner mitochondrial membrane?

The outer membrane is more lipid-rich than the inner membrane, which contains more proteins.

What is the role of dynamin in vesicle formation?

Dynamin is involved in the pinching off of vesicles from the membrane.

What is the significance of the unfolded protein response (UPR) in the ER?

To ensure the proper folding of proteins and maintain ER homeostasis.

How does oxidative stress contribute to apoptosis?

It can initiate the apoptotic signaling pathways.

What role does the lysosomal enzyme mannose-6-phosphate play?

It directs lysosomal enzymes to the lysosomes for degradation processes.

What are soluble secretory proteins?

Proteins secreted outside the cell through exocytosis.

What types of proteins exist in the mitochondrial matrix?

Matrix proteins that perform various functions including respiration.

How does the body rely on endocytosis for immune response?

By engulfing pathogens and presenting antigens for immune activation.

What is the primary energy-producing pathway that occurs in mitochondria?

The citric acid cycle and oxidative phosphorylation together produce ATP.

What is the relationship between exocytosis and neurotransmission?

Neurotransmitters are released through exocytosis from neuronal vesicles.

How is mitochondrial biogenesis regulated?

Through signaling pathways that respond to cellular energy needs.

What are the consequences of compromised lysosomal function?

Accumulation of undegraded materials can lead to lysosomal storage diseases.

What types of proteins require post-translational modifications in the ER?

Secretory proteins and membrane proteins.

What are the major roles of mitochondria in cellular metabolism?

ATP production, metabolite exchange, and regulation of metabolic pathways.

What happens to the respiratory chain if one component is inhibited?

It can lead to an accumulation of reduced electron carriers and decreased ATP production.

What triggers the movement of surface receptors during endocytosis?

Binding of ligands such as hormones or nutrients.

What is a major result of mitochondrial dysfunction in cells?

Increased susceptibility to apoptosis or impaired cellular metabolism.

What phenomenon is observed in rapidly dividing cancer cells in relation to glycolysis?

They often utilize aerobic glycolysis despite the presence of oxygen, known as the Warburg effect.

What is the primary structure of the mitochondrial DNA?

Circular and lacking introns.

What is emphasized in the 2013 Nobel Prize awarded for vesicle traffic research?

Understanding the machinery regulating vesicle transport in cells.

Why is it important for mitochondria to maintain a membrane potential?

It is essential for ATP synthesis and maintaining mitochondrial function.

What is the result of insufficient mitochondrial protein import?

Compromised mitochondrial function and potential cell death.

How does calcium accumulation in mitochondria influence cellular processes?

It modulates energy production and apoptosis.

What do the terms 'apoptotic stimulus' refer to?

Factors like oxidative stress or DNA damage that initiate apoptosis.

What is the importance of the cytosolic ribosomes' location?

They determine the fate of nascent proteins based on their localization signals.

What occurs at the contact sites between ER and mitochondria?

They facilitate lipid and calcium exchange between the two organelles.

What is the benefit of vesicle coating in endocytosis?

It ensures selective and efficient transport of cargo to destinations.

How are mitochondrial proteins primarily synthesized?

They are synthesized in the cytosol and imported into mitochondria post-translationally.

What is the turnover of ATP generated from glucose during glycolysis?

Approximately 32 ATP molecules can be generated from one glucose molecule completely oxidized.

What triggers the vesicle fusion in the process of exocytosis?

The interaction of SNARE proteins between the vesicle and target membranes.