30 Questions
Which organelle actively transports H+ protons into the lysosome from the cytosol producing the acidic environment?
H+ -ATPase
Where are lysosomal enzymes synthesized before being transported to the Golgi apparatus for modification?
Rough endoplasmic reticulum
What maintains the low pH within the lysosomes?
H+ -ATPase
What is the main function of lysosomes in the cell?
Intracellular digestion
Which type of enzymes are lysosomal enzymes?
Acid hydrolases
What is the shape of lysosomes?
Spherical
What are the lysosomal enzymes capable of breaking down?
All types of biological polymers
Where are lysosomal enzymes bud from to form primary lysosomes?
Golgi apparatus
What is the diameter range of lysosomes?
Up to 1 μm
What do lysosomes contain to maintain the acidic environment?
More than 50 different hydrolytic enzymes
In which organelle does the synthesis of acetyl CoA take place?
Mitochondrion
What is the waste product when acetyl CoA enters the citric acid cycle?
$CO_2$
Where do the high-energy electrons enter in the electron-transport chain?
Inner mitochondrial membrane
What is the enzyme responsible for the synthesis of ATP from ADP and inorganic phosphate?
ATP synthase
How many molecules of ATP are formed for each NADH in the electron-transport chain?
3
What is the function of mitochondria in the intrinsic pathway of apoptosis?
Storage of calcium ions
What are reactive oxygen species (ROS) produced as by-products of?
Oxygen metabolism
Which type of fat tissue is involved in the production of heat, and contains more vessels and mitochondria than white fat?
Brown fat tissue
How is the human mitochondrial genome inherited?
Maternally
During zygote formation, which genome does a sperm cell contribute to the egg cell?
Nuclear genome
What is the function of lysosomes?
Digest cellular waste and extracellular components
How are autophagosomes and multivesicular bodies (MVBs) related to lysosomes?
Autophagosomes form to digest unnecessary or damaged cell organelles, and MVBs are developed for sorting ingested macromolecules before fusion with lysosomes
How do peroxisomes replicate?
By fission
What is a key function of peroxisomes?
Breakdown of fatty acids, detoxification, and lipid biosynthesis
What is the main function of mitochondria?
Produce ATP using molecular oxygen
What are the four main compartments of mitochondria?
Outer membrane, intermembrane space, inner membrane, and matrix
What is the function of the inner mitochondrial membrane?
Contains specific enzyme complexes and ATP synthase
Where does anaerobic glycolysis take place?
In the cytoplasm
What is the function of the outer membrane of mitochondria?
Contains porin molecules for transport of pyruvate, fatty acids, and other molecules
What is the composition of the intermembrane space of mitochondria?
Chemically similar to the cytosol
Study Notes
Cellular Organelles: Lysosomes, Peroxisomes, and Mitochondria
- Lysosomes are organelles containing hydrolytic enzymes that digest cellular waste and extracellular components, formed from the fusion of primary and secondary lysosomes.
- Autophagosomes form to digest unnecessary or damaged cell organelles, and multivesicular bodies (MVBs) are developed for sorting ingested macromolecules before fusion with lysosomes.
- Peroxisomes are metabolic compartments surrounded by a single membrane, derived from the endoplasmic reticulum (ER), and contain over 60 different enzymes, including catalase and urate oxidase.
- Peroxisomes are involved in processes such as breakdown of fatty acids, detoxification, and lipid biosynthesis, including the synthesis of cholesterol, bile acids, and plasmalogens.
- Peroxisomes replicate by fission and contain integral membrane proteins synthesized in the ER, with a half-life of only 5 days.
- Mitochondria are energy organelles that use molecular oxygen to produce ATP, formed from pre-existing mitochondria by fission or budding.
- Mitochondria have four main compartments: outer membrane, intermembrane space, inner membrane, and inner space filled with matrix, containing specific enzyme complexes and mitochondrial DNA.
- The inner mitochondrial membrane is folded into cristae, contains phospholipid cardiolipin, and houses the enzymes of the respiratory chain and ATP synthase.
- Mitochondria serve as the energy center of the cell, converting energy from food into ATP through a process that includes anaerobic glycolysis, taking place in the cytoplasm.
- The outer membrane of mitochondria is smooth and contains porin molecules that form large aqueous channels for transport of pyruvate, fatty acids, and other molecules.
- The intermembrane space of mitochondria is chemically similar to the cytosol, while the inner membrane is highly specialized, containing specific transport proteins and being impermeable to ions.
- The inner mitochondrial space is filled with the matrix, where specific enzyme complexes metabolize pyruvate and fatty acids to acetyl CoA, and mitochondrial DNA and ribosomes are present.
Test your knowledge of lysosomes, peroxisomes, and mitochondria with this quiz on the functions and characteristics of these cellular organelles.
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