Cell Biology: Cytoplasm and Organelles

Cytoplasm

• Cytoplasm is the area within the plasma membrane, but outside the nucleus.
• The cytoplasm carries out most cellular functions.
• Composed of cytosol, organelles, and inclusions.

Cytosol

• Cytosol is a jelly-like fluid that suspends other cytoplasmic components.
• It's primarily water with dissolved ions and crucial enzymes.
• Some enzymes break down nutrients (sugars, amino acids, lipids) to provide energy and building blocks for cellular processes.
• Makes up approximately half the cytoplasm's volume in many cell types.

Cytoplasmic Organelles

• Organelles are specialized compartments that divide the cell's biochemical activities.
• Prevention of interfering reactions between biochemical reactions.
• Organelles are typically membrane-bound (similar composition to plasma membrane, but lack glycocalyx).
• Organelle abundance varies depending on the cell type and its specific functions.
• Examples: ribosomes, ER (smooth and rough), Golgi apparatus, lysosomes, mitochondria, peroxisomes, cytoskeleton, centrioles.

Ribosomes

• Ribosomes are protein production sites.

• Small, dark-staining granules.

• Not membrane-bound—composed of proteins and ribosomal RNA (rRNA).

• Two subunits (like an acorn).

• Ribosomes create proteins needed for internal and external cellular functions.

• Free ribosomes: Located in the cytosol; produce proteins for use within the cell.

• Bound ribosomes: Attached to the rough endoplasmic reticulum; produce proteins for export from the cell or membrane integration.

• Protein assembly (translation) is guided by the cell's DNA instructions transferred via messenger RNA (mRNA).

This quiz covers key concepts of cytoplasm and its components, including the roles of cytosol and various organelles. Understand how these cellular structures contribute to overall cell function and organization. Test your knowledge on the specific functions and characteristics of organelles.