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What are the major functions of the organelles?
What are the major functions of the organelles?
What is meant by compartmentalization in cell biology?
What is meant by compartmentalization in cell biology?
It refers to the isolation of individual organelles by membranes.
The endomembrane system includes only the nucleus and the Golgi apparatus.
The endomembrane system includes only the nucleus and the Golgi apparatus.
False
Which part of the Endoplasmic Reticulum is studded with ribosomes?
Which part of the Endoplasmic Reticulum is studded with ribosomes?
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Two types of ER are Rough ER and _____ ER.
Two types of ER are Rough ER and _____ ER.
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Proteins are imported into the RER through a process known as __________.
Proteins are imported into the RER through a process known as __________.
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What is the main function of Smooth ER?
What is the main function of Smooth ER?
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The ER membrane is continuous with the nuclear envelope.
The ER membrane is continuous with the nuclear envelope.
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The import of proteins into the Rough ER is a __________ process.
The import of proteins into the Rough ER is a __________ process.
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What does the ER signal sequence do?
What does the ER signal sequence do?
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Study Notes
Membrane Bound Organelles
- Completely surrounded by a phospholipid bilayer akin to the plasma membrane.
- Enables compartmentalization, preventing the mixing of organelle interiors with cytosol.
- Requires a coordinated transport system for inter-organelle communication through vesicular transport, which is an ATP-dependent process.
Functions of Membranous Organelles
- Protein synthesis primarily occurs in the Endoplasmic Reticulum (ER) and Golgi apparatus.
- Energy production is managed by mitochondria.
- Waste management is handled by lysosomes and peroxisomes.
Organelle Duplication and Growth
- Organelle construction is not de novo; information for construction is contained within the organelles.
- During cell division, organelles must be duplicated.
- Cells enlarge existing organelles by incorporating new phospholipids and proteins, facilitating division during cytokinesis.
Endomembrane System
- Comprises a complex and dynamic network that organizes cellular compartments.
- Components include the nucleus, Endoplasmic Reticulum (ER), Golgi apparatus, lysosomes, endosomes, vacuoles, and vesicles.
Protein Trafficking in the Endomembrane System
- Proteins synthesized and processed in the ER and Golgi are destined for secretion, incorporation into the plasma membrane, or lysosomes.
Endoplasmic Reticulum (ER)
- Composed of flattened sacs called cisternae, which are in communication with the nucleus and plasma membrane.
- The internal compartment is known as the lumen, accounting for about 10% of total cell volume.
- Features distinct regions: Rough ER (with ribosomes) and Smooth ER (ribosome-free).
Types of Endoplasmic Reticulum
- Rough ER: Ribosome-studded exterior, involved in protein and phospholipid synthesis, initial processing, and sorting of proteins.
- Smooth ER: Lacks ribosomes; functions primarily in the synthesis of transport vesicles and can be referred to as transitional ER.
Functions of the Endoplasmic Reticulum
- Synthesis: Produces phospholipids, lipids, and proteins.
- Storage: Stores intracellular calcium.
- Transport: Site for transport vesicle production.
Protein Import into Rough ER
- The import of proteins into the Rough ER occurs co-translationally, where proteins enter as they are being synthesized by ribosomes.
- This is different from post-translational import seen in other organelles (chloroplasts, mitochondria, peroxisomes, nucleus).
Co-translational Protein Synthesis
- Proteins entering the ER include transmembrane proteins that remain within the ER membrane and lumen, and proteins destined for Golgi, plasma membrane, lysosome, or secretion.
- Requires an ER signal sequence (16-30 amino acids) at the N-terminal end of the peptide.
Role of the Signal Recognition Particle (SRP)
- A protein complex binds to the ER signal sequence in the cytoplasm.
- The ER membrane contains receptors for both the SRP and the ribosome to facilitate protein transport across the ER membrane.
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Description
This quiz explores the differences between membrane-bound and non-membrane organelles. It delves into the structural aspects of these organelles and their specific roles in cellular compartmentalization. Perfect for students studying animal structure and development.
