30 Questions
Which organelles are membrane bound?
Nucleus, Endoplasmic reticulum, Golgi apparatus
What is the main function of the nucleus?
Store genetic information and act as a control center
What is the composition of the nuclear envelope?
Double membrane with inner and outer nuclear membrane
What is found in the nuclear interior?
Nucleoplasm, Chromatin, Nuclear bodies
Which organelle disassembles during cell division?
Nucleus
Which organelle is involved in the exchange of molecules between the perinuclear space and the nuclear interior?
Inner nuclear membrane
Which proteins enable the fusion of vesicles with correct target membranes?
SNARE proteins
What is the function of COPI vesicles in vesicle transport?
Transport from GA back to ER
What is the primary role of Clathrin-coated vesicles?
Endocytosis and transport to lysosomes
What are v-SNAREs and t-SNAREs involved in?
Fusion of vesicles with correct target membranes
What is the function of COPII proteins in vesicle transport?
Transport from ER to GA
What is the main function of lysosomes?
Cellular digestion
What is the function of the nuclear lamina?
Maintains the shape and stability of the nuclear envelope, binds DNA, and regulates nuclear processes
What is the role of the nuclear pore complex?
Enables the translocation of macromolecules into and out of the nucleus
What is the function of the nucleolus?
Site of intense rRNA transcription and processing, and ribosomal subunit assembly
Where are genes for 5.8S, 18S, and 28S rRNAs located?
In the short arm of acrocentric chromosomes and transcribed by RNA polymerase I
What happens to nucleoli at the beginning of mitosis?
They disassemble
What is the role of the perinuclear space?
Continuous with the endoplasmic reticulum lumen and measures 20 to 40 nm
What is the main function of rough endoplasmic reticulum (ER)?
Protein synthesis and processing
Where are most cell lipids, including phospholipids and cholesterol, synthesized?
Smooth endoplasmic reticulum (ER)
What is the function of the sarcoplasmic reticulum?
Storage and release of calcium ions
Where does mRNA relocate to after leaving the nucleus?
Cytoplasm
What is the main function of smooth endoplasmic reticulum (ER)?
Synthesizing lipid molecules
Which organelle is the largest in most cells, representing about 10% of the total cell volume?
Endoplasmic reticulum (ER)
What is the main function of Smooth Endoplasmic Reticulum (SER)?
Detoxifying compounds in specialized cells like liver cells
What is the role of Sarcoplasmic Reticulum (SR) in muscle cells?
Storing Ca2+ ions for muscle contraction
What triggers Ca2+ release from Sarcoplasmic Reticulum (SR) during muscle contraction?
Acetylcholine binding to receptors in the sarcolemma
What is the main function of Golgi Apparatus (GA) in the cellular secretory pathway?
Acting as a sorting station in the cellular secretory pathway
How are the Golgi stacks linked together within the Golgi Apparatus (GA)?
By tubular connections
What occurs at the cis-face of Golgi Apparatus (GA) in the processing pathway?
Vesicles containing proteins and lipids enter and undergo modification
Study Notes
Cellular Organelles and Their Functions
- Lipid flippases and floppases are ATP-dependent membrane proteins that maintain phospholipid distribution in the bilayer.
- Smooth Endoplasmic Reticulum (SER) detoxifies compounds in specialized cells like liver cells and increases detoxification enzymes in response to drugs or alcohol.
- Sarcoplasmic Reticulum (SR) is specialized endoplasmic reticulum in muscle cells, storing Ca2+ ions for muscle contraction.
- SR consists of terminal cisternae communicating with T-tubules and plays a crucial role in muscle contraction and relaxation.
- Muscle contraction is mediated by acetylcholine binding to receptors in the sarcolemma and triggering Ca2+ release from SR.
- Muscle relaxation occurs when Ca2+ is pumped back to the SR by Ca2+-ATPase pumps, allowing the muscle fiber to relax.
- Golgi Apparatus (GA) serves as a sorting station in the cellular secretory pathway and is involved in processing and delivering cellular components.
- GA is composed of flat sacs (cisternae) forming the Golgi stack, linked together by tubular connections.
- The Golgi stacks are linked by microtubules, stabilizing the position of GA within the cell and enabling transport of vesicles among cisternae.
- The Golgi apparatus has a horseshoe shape with distinct cis and trans faces, playing different roles in the processing pathway.
- The cisternae of the Golgi serve as chambers for different chemical reactions, including glycosylation and assembly of molecules.
- Vesicles containing proteins and lipids enter the cis-face of GA, undergo modification, and are delivered to specific intracellular or extracellular locations.
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