Cell Structure and Function Quiz

Cell Structure and Function

• Cell Membrane Structure: Composed of a phospholipid bilayer with hydrophilic heads and hydrophobic tails. Proteins, glycolipids, and glycoproteins are embedded within the bilayer. The membrane has a dynamic structure and is selectively permeable.

Cellular Components

• Mitochondria: Organelles with an outer and inner membrane; the inner membrane is folded into cristae, increasing surface area for energy production. The matrix houses the enzymes of the Krebs cycle and the electron transport chain.

• Golgi Apparatus: A stack of flattened sacs (cisternae). The cis face receives proteins, while the trans face packages and sorts them for transport. Functions in protein modification and packaging.

• RER (Rough Endoplasmic Reticulum): Network of interconnected membranes with ribosomes attached. Site of protein synthesis and modification, particularly for proteins destined for secretion or insertion into membranes.

• Lysosomes: Membrane-bound organelles containing digestive enzymes. Primary lysosomes contain undigested material or pathogens; secondary lysosomes contain material that is being digested.

• Centrioles: Cylindrical structures involved in cell division. Found in pairs, they form the centrosome.

• Cilia: Hair-like projections from the cell surface, involved in movement of substances across the cell surface. Basal bodies, similar to centrioles, anchor cilia.

• Microvilli: Finger-like projections of the cell membrane, increasing surface area for absorption. Internal support is provided by actin filaments anchoring them to the cell membrane.

• Nucleus: Contains the cell's genetic material (DNA) organized into chromosomes. Contains a nucleolus, site of ribosome assembly.

Epithelial Tissues

• Simple Squamous Epithelium: Single layer of flattened cells; found in lung alveoli and blood capillaries, facilitating diffusion and filtration.

• Simple Cuboidal Epithelium: Single layer of cube-shaped cells; found in kidney tubules, involved in secretion and absorption.

• Simple Columnar Epithelium: Single layer of column-shaped cells; found in the digestive tract, involved in absorption and secretion.

• Pseudostratified Columnar Epithelium: Appears layered but all cells contact the basement membrane; found in the respiratory tract (trachea), involved in secretion and movement of mucus.

• Stratified Squamous Epithelium (Keratinized): Multiple layers of flattened cells; found in skin, protecting against abrasion.

• Stratified Squamous Epithelium (Non-Keratinized): Multiple layers of flattened cells; found in oral cavity, moist environment protection.

• Transitional Epithelium: Cells that can change shape; found in the urinary bladder, accommodating stretching.

Connective Tissues

• Reticular Connective Tissue: Thin reticular fibers form a supportive network; found in lymph nodes and bone marrow.

• Mucoid Connective Tissue: Gelatinous matrix; found in umbilical cord.

• Adipose Connective Tissue: Fat cells (adipocytes); stores energy, provides insulation, and cushioning. White adipose (unilocular) and brown adipose (multilocular).

Blood Cell Types

• Neutrophils: Granulocytes; phagocytic cells, involved in fighting infections.

• Eosinophils: Granulocytes; involved in allergic reactions and parasitic infections.

• Basophils: Granulocytes; release histamine and other mediators in allergic reactions.

• Lymphocytes: Involved in the specific immune response.

• Monocytes: Macrophages; phagocytic cells in tissues.