Mitochondria Functions and Metabolism Quiz

Cell Biology - STBP1023

• Course taught by Dr. Nurul Yuziana Mohd Yusof
• Focuses on the structure and function of cells.

Structure & Functions of Cells

• Organelles, non-organelles, and other subcellular components are examined.
• The different types of cells are reviewed in Part 1.
• Part 2 details the organelles, including the nucleus, mitochondrion, Endoplasmic Reticulum, Golgi Apparatus, Lysosome & Peroxisome, Vacuole, and Chloroplast.
• Part 3 covers non-organelles: Cell Wall, Cytoskeleton, Ribosomes, cell coats, and cell junctions.
• Three different kingdoms – Eukarya, Bacteria, and Archaea.

Types of Cells

• Eukaryotic cells contain a nucleus and other membrane-bound organelles.
• Prokaryotic cells lack a nucleus or membrane-bound organelles.
• Archaea: Structurally similar to prokaryotic cells, but have several genes and biochemical pathways similar to eukaryotes. Extremophiles (e.g., methanogens, halophiles, acidophiles, thermophiles).

Prokaryotic Cell

• Lack a nucleus and membrane-bound organelles.
• Key components: plasma membrane, cell wall, DNA (nucleoid), ribosomes, capsule, and flagella.

Archaeal Cell

• Similar in size to prokaryotic cells.
• Two membranes.
• Contain DNA and ribosomes.
• Have some metabolic pathways similar to those in eukaryotic cells.
• Often found in extreme environments (extremophiles).

Eukaryotic Cells (Animal and Plant)

• Eukaryotic cells are characterized by a nucleus and membrane-bound organelles.
• Diagrams illustrating the different organelles and their locations within animal and plant cells are included.

Subcellular Components (Organelles and Non-Organelles)

• Organelles (membrane-bound): nucleus, mitochondrion, endoplasmic reticulum (rough and smooth), Golgi complex, vacuoles, peroxisomes, lysosomes, chloroplast
• Non-organelles (non-membrane-bound): plasma membrane, cell wall, cytoskeleton (microtubules, microfilaments, intermediate filaments), cytosol, ribosomes

Homeostasis

• A state of balance among all body systems needed for survival and function.
• Involves regulation through systems to maintain optimal conditions.
• The relationship with cell organelles is crucial.
• Cell organelles are specialized for maintaining specific aspects of cellular balance.
• The integrated network of organelles allows coordinated responses and understanding these relationships is helpful for medical research, disease treatment, and cell engineering.

The Nucleus

• Structure: double membrane (nuclear envelope), nucleoplasm, nucleolus, chromatin, nuclear pores
• Function: stores genetic information (DNA—chromosomal organization), DNA replication, regulation of gene expression, control of protein synthesis.
• Role in Homeostasis: coordination of cellular responses, maintenance of genetic integrity.

The Mitochondrion

• Structure: outer and inner membranes (cristae), matrix
• Function: ATP production through cellular respiration (oxidative phosphorylation, electron transport chain, proton gradient), role in metabolic pathways (citric acid cycle, fatty acid oxidation, amino acid metabolism).
• Role in Homeostasis: energy supply for cellular processes, regulation of ATP availability, and adjustment of metabolic rate.

The Endoplasmic Reticulum

• Structure: smooth ER versus rough ER; structural differences and distribution in cells, continuous membrane system, connection to the nuclear envelope; transport mechanisms; spatial organization.
• Function: Protein synthesis and folding (rough ER—ribosome attachment, protein translocation, quality control); Lipid synthesis and detoxification (smooth ER—membrane lipid production, steroid hormone synthesis, drug metabolism).
• Role in Homeostasis: Quality control of proteins; unfolded protein response; protein trafficking, ER stress management; modulation of lipid levels, membrane composition regulation, lipid distribution, and cellular stress response.

Golgi Apparatus

• Structure: stacked cisternae; structural organization; membrane composition; vesicle formation; polarized structure (cis & trans faces)
• Function: Modification of proteins and lipids (glycosylation, protein processing, sorting signals), packaging for secretion and/or delivery; vesicle formation; protein targeting; quality control.
• Role in Homeostasis: regulation of cellular transport, membrane traffic control, protein distribution, vesicle targeting, maintenance of cellular communications, secretory pathway regulation, signal molecule processing , and membrane composition control.

Secretory Vesicles

• Contains proteins and substances processed by the Golgi complex.
• Vesicles move from the Golgi to the plasma membrane and discharge their contents into the extracellular space.

Lysosomes and Peroxisomes

• Structure: membrane-bound vesicles; single membrane; specific protein composition
• Function: breakdown of macromolecules (protein, lipid, carbohydrate processing), autophagy (cellular recycling), role in stress response.
• Peroxisomes: breakdown of fatty acids, hydrogen peroxide production, detoxification processes.
• Role in Homeostasis: cellular cleanup, recycling, waste management, material recycling, quality control, and regulation of metabolic byproducts (toxin elimination, ROS management)

Vacuoles

• Structure: membrane (tonoplast); selective transport proteins
• Function: storage (water retention, turgor pressure maintenance), nutrient/ion storage (Ca2+, K+, NO3-), waste products; secondary metabolites, detoxification; defense function (alkaloids, tannins, protease inhibitors)
• Role in Homeostasis: turgor pressure regulation(cell expansion and growth, structural support); pH and ion balance (cytoplasmic pH regulation, ion concentration control, metal ion sequestration, salt stress management).

Chloroplasts

• Structure: membrane systems, internal compartments (stroma, thylakoid membrane)
• Function: Photosynthesis (light-dependent reactions, electron transport chain, ATP synthesis, NADPH production; carbon fixation, Calvin cycle, sugar synthesis, starch production, photorespiration).
• Role in Homeostasis: energy balance; glucose production, ATP generation, NADPH supply, energy storage as starch; maintenance of redox state (ROS management, antioxidant production, photoprotection mechanisms)

Cell Walls

• Structure: varies across cell types (plant, fungal, bacterial)
• Function: provides structural support (mechanical strength, shape maintenance, growth regulation), protection (physical barrier, stress resistance, environmental protection, selective permeability), and plays a role in cell-cell communication and interaction (recognition, transport regulation).
• Note: cell wall is rigid and encases the plant cell.

Cytoskeletons

• Structure: composed of microtubules, microfilaments, and intermediate filaments.
• Function: maintains and establish cell shape; important roles in cell movement and cell division; positioning of organelles within cytoplasm; influence in cell motility and cytoplasmic streaming; structural support.
• Role in Homeostasis: structural homeostasis, transport homeostasis, mechanical response, and force distribution.

Ribosomes

• Structure: prokaryotic and eukaryotic ribosomes, differing in size (70S and 80S)
• Function: Protein synthesis
• Role in Homeostasis: protein homeostasis; regulation of translation; energy balance and efficiency; resource allocation

Cell Coats and Junctions

• Cell Coats (glycocalyx): trans-membrane adsorbed glycoproteins, glycolipid with attached carbohydrate, function as cell markers and source of energy
• Cell-to-cell junctions: strengthen the cell surface and hold cells together , important in cell recognition, and intercellular communications (gap junctions, tight junctions and desmosomes)