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Questions and Answers
What is a main function of the smooth endoplasmic reticulum (SER) in liver cells?
What is a main function of the smooth endoplasmic reticulum (SER) in liver cells?
- Protein synthesis
- Regulation of glycoprotein production
- Hormone secretion
- Glycogen metabolism (correct)
Which organelle is primarily responsible for processing and packaging proteins and lipids?
Which organelle is primarily responsible for processing and packaging proteins and lipids?
- Nucleus
- Mitochondria
- Rough endoplasmic reticulum
- Golgi apparatus (correct)
What type of lysosome is characterized as a homogeneous vesicle that has not yet entered a digestive process?
What type of lysosome is characterized as a homogeneous vesicle that has not yet entered a digestive process?
- Multi-vesicular body
- Primary Lysosome (correct)
- Heterophagosome
- Secondary Lysosome
Which surface of the Golgi stack faces the nucleus?
Which surface of the Golgi stack faces the nucleus?
What is the role of the cytochrome P450 enzymes in the smooth endoplasmic reticulum?
What is the role of the cytochrome P450 enzymes in the smooth endoplasmic reticulum?
In which type of cells is jaundice in newborns attributed to underdeveloped smooth endoplasmic reticulum?
In which type of cells is jaundice in newborns attributed to underdeveloped smooth endoplasmic reticulum?
What is formed by the fusion of a secondary lysosome with solid particles?
What is formed by the fusion of a secondary lysosome with solid particles?
Which of the following structures can be visualized using special stains in light microscopy due to its position in protein-secreting cells?
Which of the following structures can be visualized using special stains in light microscopy due to its position in protein-secreting cells?
What visible characteristic indicates the presence of granules at the apical pole of secretory cells under light microscopy?
What visible characteristic indicates the presence of granules at the apical pole of secretory cells under light microscopy?
What is the primary function of mitochondria in cells?
What is the primary function of mitochondria in cells?
Which of the following structures is NOT part of the mitochondria?
Which of the following structures is NOT part of the mitochondria?
How do new mitochondria originate?
How do new mitochondria originate?
Which of the following best describes the 'intercristae' space within mitochondria?
Which of the following best describes the 'intercristae' space within mitochondria?
Which function is NOT performed by mitochondria?
Which function is NOT performed by mitochondria?
What is one potential consequence of mitochondrial disease?
What is one potential consequence of mitochondrial disease?
What role does the endoplasmic reticulum play in the cell?
What role does the endoplasmic reticulum play in the cell?
What is the fate of indigestible compounds processed by lysosomes?
What is the fate of indigestible compounds processed by lysosomes?
What structures are referred to as lipofuscin in long-lived cells?
What structures are referred to as lipofuscin in long-lived cells?
How are lysosomal enzymes processed after being synthesized in the RER?
How are lysosomal enzymes processed after being synthesized in the RER?
What triggers the autolysis process in cells?
What triggers the autolysis process in cells?
What is the primary function of peroxisomes?
What is the primary function of peroxisomes?
Which of the following statements about lysosomes is true?
Which of the following statements about lysosomes is true?
In lysosomal storage disorders, what happens to specific molecules within the cells?
In lysosomal storage disorders, what happens to specific molecules within the cells?
What distinguishes primary lysosomes from secondary lysosomes?
What distinguishes primary lysosomes from secondary lysosomes?
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Study Notes
Endoplasmic Reticulum (ER)
- Network of interconnected membranes that extends throughout the cytoplasm of eukaryotic cells.
- Two types: Rough ER (RER) and Smooth ER (SER).
- RER: studded with ribosomes, involved in protein synthesis and modification.
- SER: lacks ribosomes, involved in lipid synthesis, detoxification, and calcium storage.
Golgi Complex (Apparatus)
- Processes, packages, and sorts macromolecules (proteins and lipids).
- Composed of flattened sacs called cisternae, arranged in stacks.
- Has two faces: cis face (convex, immature) and trans face (concave, mature).
- Transfer vesicles from RER fuse with the cis face, and secretory vesicles bud from the trans face.
Lysosomes
- Membrane-bound organelles containing hydrolytic enzymes.
- Involved in intracellular digestion of various materials.
- Two types: primary lysosomes (undigested material) and secondary lysosomes (actively digesting).
- Secondary lysosomes include heterophagosomes, multi-vesicular bodies, and autophagosomes.
- Lysosomal storage disorders occur when specific lysosomal enzymes are absent or inactive, leading to accumulation of undigested material within cells.
Peroxisomes (Microbodies)
- Small, membrane-bound organelles containing oxidative enzymes.
- Involved in detoxification of harmful molecules using catalase enzyme, producing hydrogen peroxide (H2O2).
- Participate in lipid metabolism.
Secretory Granules
- Membrane-bound granules containing secretory proteins.
- Formed from RER and transported through Golgi complex.
- Stored in the apical pole of secretory cells.
- Involved in exocytosis, releasing their contents outside the cell.
Mitochondria (The powerhouse of the cell)
- Membranous organelles responsible for energy production (ATP).
- Consists of two membranes: outer smooth membrane and inner folded membrane (cristae).
- Two spaces: outer intermembrane space and inner matrix space.
- Contains mitochondrial DNA, RNA, ribosomes, enzymes, and dense granules rich in calcium ions.
- Originate from existing mitochondria through growth and division (binary fission).
Medical Application of Mitochondria
- Mitochondrial disease: dysfunction of mitochondria, reducing energy production and damages brain, heart, liver, muscles, and kidneys.
- Causes symptoms like muscle weakness, loss of motor control, pain, gastrointestinal disorders, poor growth, cardiac disease, and liver disease.
Functions of the Smooth Endoplasmic Reticulum (SER)
- Lipid synthesis, particularly in steroid-producing cells like adrenal cortex cells.
- Glycogen metabolism: enzymes involved in regulating glycogen metabolism are associated with the SER membrane (e.g., liver cells).
- Regulation of mineral metabolism, like HCL production in the stomach.
- Calcium storage: in skeletal and cardiac muscle fibers to control muscle contraction.
- Drug detoxification: due to cytochrome P450 enzymes present in SER (especially liver cells).
Medical Application of SER
- Underdeveloped SER in liver cells in newborns leads to jaundice.
- Jaundice results from the accumulation of bilirubin, normally metabolized by SER enzymes in liver cells and excreted as bile.
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