Ch 3.2 - The Cytoplasm & Cellular Organelles

What is the Cytoplasm?

• the entire contents within the cell membrane, excluding the nucleus. It includes the cytosol and various organelles (specialized structures that perform specific functions, analogous to organs within the body).

What is a Nucleus?

• the membrane-bound organelle that contains the cell's genetic material (DNA) and is responsible for regulating gene expression and maintaining the integrity of genes. It serves as the control center for cellular activities.

What are the organelles of the Endomembrane System?

• a group of membranous structures that work together to modify, package, and transport lipids and proteins within the cell. This includes the endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles.

What is the Endoplasmic Reticulum?

• a network of membranous tubules and sacs that is involved in the synthesis of proteins and lipids, and plays a key role in cellular transport. It is divided into rough and smooth types, with rough ER associated with ribosomes.

What is Rough ER

• a type of endoplasmic reticulum that is studded with ribosomes on its cytoplasmic surface, giving it a "rough" appearance. It is primarily involved in the synthesis of proteins that are either secreted from the cell, incorporated into the cell's plasma membrane, or sent to an organelle.

What is Smooth ER

• a type of endoplasmic reticulum that lacks ribosomes, giving it a smooth appearance. It is involved in the synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons.

What is Golgi Apparatus?

• a cellular organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles. It consists of stacked, flattened membranes and plays a key role in processing and distributing cellular products.

  • It has a cis face (receiving side, near ER) and a trans face (shipping side), with medial cisternae in between.

What are Lysomes?

• Spherical membrane-bound organelles containing enzymes that digest macromolecules, old cell parts, and microorganisms. They play a crucial role in cellular waste disposal and recycling.

What is Mitochondria

• double-membraned organelles known as the powerhouses of the cell, responsible for producing ATP through cellular respiration. They are involved in energy metabolism and cell signaling.

Structure of Mitochondria?

• They have an outer membrane (smooth and permeable) and a highly folded inner membrane (forming cristae, which increase surface area). The space between the membranes is the intermembrane space, and the inner compartment is the mitochondrial matrix.

What are Peroxisomes?

• Organelles that contain enzymes for oxidizing fatty acids and detoxifying harmful substances. They play a vital role in lipid metabolism and the breakdown of hydrogen peroxide.

What is a Cytoskeleton?

• A network of protein filaments and tubules that provide structural support, shape, and transportation within the cell. It plays a crucial role in cell division, movement, and intracellular transport.

  • Made up of microfilaments, intermediate filaments, and microtubules.

What are Microtubles

• Cytoskeletal structures made up of tubulin proteins, providing support and shape to cells. They play crucial roles in cell division, intracellular transport, and maintaining cell structure.

What are Intermediate Filaments?

• Fibrous proteins supercoiled into thicker cables. They are intermediate in thickness between microtubules and microfilaments. They provide tensile strength and stability to cells, anchoring organelles and cells together.

What are Microfilaments (Actin Filaments)?

• The thinnest components of the cytoskeleton, solid rods made of actin protein. They are involved in cellular movement, muscle contraction (interacting with myosin), amoeboid movement, formation of microvilli (increasing surface area), and cleavage furrow formation during cytokinesis.