Cell Biology and Health Quiz

Health and Disease

• Health, according to WHO, is defined as a state of complete physical, mental, and social well-being, not just the absence of disease.
• Cells play a crucial role in health and disease development; molecular alterations can lead to organelle damage and dysfunctional cell functions.

Lysosomes

• Lysosomes are membrane-bound vesicles rich in hydrolase enzymes like proteases and lipases, critical for digesting materials within cells.
• They digest external materials via endocytosis and are involved in phagocytosis through phagocytes, leading to the formation of phagolysosomes.

Autophagy and Proteasome Functions

• Autophagy allows cells to degrade their own proteins or organelles, particularly those that are damaged or aging, to recycle materials for new molecule production or disposal.
• Proteasomes degrade denatured proteins, especially under stress conditions, playing a vital role in antigen presentation via MHC class 1 molecules.

Cellular Damage and Reactive Oxygen Species (ROS)

• Exposure to environmental factors, like UV or certain metals, can enhance ROS production, leading to cellular injury and potentially contributing to aging and tumorigenesis.
• ROS can cause necrosis or apoptosis, resulting from mitochondrial respiration or specific enzymatic reactions.

Superoxide and ROS Regulation

• Superoxide is generated during infections or mitochondrial respiration and can damage tissues; it is neutralized by superoxide dismutase (SOD) and catalase.
• SOD catalyzes the conversion of superoxide to less harmful hydrogen peroxide, which can be further degraded by catalase into water and oxygen.

Cell Proliferation Signaling

• Certain molecules can continuously signal from the membrane to the nucleus, leading to cell proliferation even in normal growth factor concentrations.
• Oncosuppressor genes, like TP53, play a critical role in regulating the cell cycle and preventing tumor formation through DNA damage response mechanisms.

p53 and Its Role

• p53, known as the "genome guardian," orchestrates cell cycle arrest or apoptosis upon DNA damage, preventing the propagation of mutations.
• It is activated by conditions such as hypoxia, oxidative stress, and telomere shortening, influencing cell fate decisions.

Macrophages and Neutrophils

• Macrophages and neutrophils are key phagocytic cells, with neutrophils having a short lifespan and rapid responses while macrophages are longer-lived and produce high levels of cytokines.
• Macrophages develop from monocytes, with various specialized forms residing in different tissues (e.g., Kupffer cells in the liver).

Lymphocyte Maturation and Function

• B-cells mature in the bone marrow, while T-cells require maturation in the thymus before becoming memory cells that recirculate and mount a rapid immune response upon reinfection.
• Activated lymphocytes migrate to inflamed tissues to fight infections and produce antibodies and cytokines.

Immune System Molecules

• Immune functions are mediated by membrane receptors (specific and non-specific) and soluble molecules like cytokines, which are critical during both normal and inflammatory conditions.
• Chemokines attract immune cells to infection sites, and growth factors are essential for lymphocyte proliferation and differentiation.

Inflammation and Immune Response

• Cytokines and chemokines orchestrate the immune response, facilitating the movement of immune cells to sites of infection or injury.
• The immune system relies on various molecules to maintain homeostasis and react effectively to pathogens, ensuring proper immune function.