Chapter 8-9 Cell Bio Lab

Biosynthetic / Secretory Pathway

Proteins are synthesized in the rough endoplasmic reticulum (RER), undergo modifications in the Golgi complex, and are sent to their final destinations.

Constitutive Secretion

Continuous transport of materials to the extracellular space.

Regulated Secretion

Storage and release of materials only upon specific signals (e.g., hormone release in endocrine cells).

Endocytic Pathway

A pathway that allows cells to uptake materials from the exterior to lysosomes through membrane invagination and vesicle budding.

Autoradiography

This technique uses radioactively labeled molecules to visualize their location within cells.

Green Fluorescence Protein

A protein that exhibits green fluorescence when exposed to light in the blue to ultraviolet range. Researchers utilize ___ to track protein movements within living cells, allowing real-time observation of cellular processes.

Endoplasmic Reticulum

A network of membranes that plays a pivotal role in the synthesis and processing of proteins and lipids.

Rough ER

Composed of cisternae, studded with ribosomes responsible for synthesizing secretory and membrane proteins.

Smooth ER

Lacks ribosomes and is involved in lipid and steroid hormone synthesis, drug detoxification, and calcium ion storage.

Golgi Complex

Crucial for post-translational processing of proteins

Cis Golgi Network

Entry point for proteins from the ER

Medial Cisternae

Golgi complex functional zones; mainly for processing enzymes

Trans Golgi Network

Golgi complex functional zones; sorting and dispatching of proteins to their destinations

Lysosomes

Membrane-bound organelles responsible for digesting cellular waste and recycling products. They contain hydrolytic enzymes activated at acidic pH and are crucial for cellular homeostasis.

Vacuoles

These organelles store nutrients, waste products, and help regulate turgor pressure in plant cells; can occupy a significant portion of the cell volume.

Posttranslational Uptake of Proteins

This process involves the import of proteins into organelles like mitochondria, chloroplasts, and peroxisomes after their synthesis is complete in the cytosol, often requiring specialized signals for successful targeting.

Structural Support

Function of the cytoskeleton; provides a dynamic scaffold that helps maintain the cell shape and resists mechanical forces.

Organization of Organelles

Function of the cytoskeleton; It positions organelles in specific locations within cells, particularly in polarized epithelial cells.

Transport Network

Function of the cytoskeleton; It serves as a track for the movement of materials and organelles, for example, during the transport of mRNA and vesicles.

Cell Motility

Function of the cytoskeleton; It drives the movement of cells via mechanisms such as amoeboid movement, cilia, and flagella.

Cell Division

Function of the cytoskeleton; It constitutes key components of the machinery for chromosome separation and cytokinesis during cell division.

Live-Cell Fluorescence Imaging

Revolutionized investigation of cytoskeletons by allowing observation of cellular processes in real time. By using fluorescently labeled cytoskeletal proteins, scientists can track their dynamic behavior in living cells.

Electron Microscopy

Cytoskeleton study; provided static images but lacked dynamic information.

Fluorescence Recovery After Photobleaching

Allow researchers to observe the dynamics of cytoskeletal structures by bleaching a region and monitoring the recovery of fluorescence.

Microtubules

1. Long, hollow, unbranched tubes made of tubulin dimers (α and β-tubulin) arranged in protofilaments (13 protofilaments form a microtubule).

2. Diameter: 25 nm; wall thickness: 4 nm; highly polar with + (β-tubulin end) and - (α-tubulin end) ends.

Microtubules

1. Serve as tracks for motor proteins (kinesins and dyneins) involved in the transport of cellular cargo.

2. Play roles in cell shape maintenance and intracellular organization.

3. Essential for mitotic spindle formation during cell division.

Microfilaments

1. Composed of actin proteins; 8 nm in diameter. Actin monomers (G-actin) polymerize to form helical filaments (F-actin).

2. Polarized with distinct structures at the plus and minus ends.

Microfilaments

1. Essential for cell locomotion and changes in cell shape; also crucial for intracellular transport and phagocytosis.

2. Example activities include the crawling of white blood cells and the expansion of the leading edge of growing axons.

Muscle Contractility

Facilitated by the interaction of actin filaments with myosin motor proteins, resulting in a shortening of muscle fibers.

Nonmuscle Motility

During the process of wound healing where cells migrate to close the gap.

Cytoskeleton

A complex and dynamic network essential for maintaining cell structure and facilitating movement and intracellular transport. Not only is it involved in structural integrity, but it also plays a critical role in many cellular processes, including motility and division.

Intermediate Filaments

1. Solid, unbranched filaments with a diameter of 10-12 nm; exhibit considerable mechanical strength.

2. Composed of a diverse set of proteins (approximately 70 distinct genes).

3. Lack polarity, differing from microtubules and microfilaments.

Intermediate Filaments

1. Provide structural support and durability for cells under mechanical stress, especially in neurons and muscle cells.

2. Function as a supportive framework that connects microtubules and microfilaments in the cytoskeletal network.

Endomembrane system

A dynamic network composed of membranes and various organelles. Its primary function is the transport of materials within the cell, facilitated by small membrane-bounded transport vesicles. These vesicles bud from donor compartments and move along microtubules and microfilaments within the cytoplasm, eventually fusing with specific target membranes to release their cargo.

Anterograde Transport

Movement from the ER to the Golgi.

Retrograde Transport

Movement from the Golgi back to the ER.