Cell Structure and Biological Molecules

Cell Structure and Function

• Cells are the basic units of life, exhibiting diverse structures and functions.
• Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells possess both.
• Key cell organelles include the nucleus (controls cell activities), mitochondria (energy production), endoplasmic reticulum (protein synthesis and transport), Golgi apparatus (modifies and packages proteins), and lysosomes (waste breakdown).
• Plant cells have unique features like cell walls and chloroplasts (photosynthesis).

Biological Molecules

• Four major classes of biological molecules include carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates are primarily used for energy storage and structural support (e.g., cellulose in plant cell walls).
• Lipids include fats, oils, and steroids, serving as energy storage, insulation, and structural components of cell membranes.
• Proteins are involved in a wide range of functions, including catalysis (enzymes), transport, support, and defense.
• Nucleic acids (DNA and RNA) store and transmit genetic information.

Cellular Respiration

• Cellular respiration is the process by which cells break down glucose to produce ATP (energy).
• Glycolysis, the Krebs cycle, and electron transport chain are the key stages.
• Aerobic respiration requires oxygen, while anaerobic respiration does not.
• Fermentation is an anaerobic pathway that produces ATP in the absence of oxygen.

Photosynthesis

• Photosynthesis is the process by which plants and some other organisms convert light energy into chemical energy (glucose).
• It occurs in chloroplasts, specifically within the thylakoid membranes (light-dependent reactions) and stroma (light-independent reactions).
• Water, carbon dioxide, and sunlight are the reactants, and glucose and oxygen are the products.
• Photosynthesis is crucial for maintaining atmospheric oxygen levels and providing energy for the food chain.

Genetics

• Genetics explores heredity, the transmission of traits from parents to offspring.
• DNA is the molecule that carries genetic information, organized into genes.
• Genes code for specific proteins, which determine traits.
• Chromosomes are structures that contain DNA and proteins, organizing the genetic material.
• Inheritance patterns, like Mendelian genetics, describe the way traits are passed down through generations.

Evolution

• Evolution is the change in heritable characteristics of biological populations over successive generations.
• Natural selection is a key mechanism of evolution, where organisms better adapted to their environment are more likely to survive and reproduce.
• Genetic variation within a population is essential for evolution to occur.
• Speciation is the process by which new species arise.

Ecology

• Ecology studies the relationships between organisms and their environment.
• Ecosystems include biotic (living) and abiotic (non-living) components.
• Food chains and webs illustrate energy flow within an ecosystem.
• Biodiversity, the variety of life on Earth, is essential for ecosystem health and stability.
• Population dynamics address factors influencing population size and growth.
• Communities are groups of populations interacting within an ecosystem.
• Biomes are large-scale ecosystems characterized by specific climate and vegetation.

Classification of Living Organisms

• Organisms are classified into hierarchical groups, reflecting evolutionary relationships.
• The Linnaean system uses taxonomic ranks (domain, kingdom, phylum, class, order, family, genus, species).
• Phylogenies (evolutionary trees) depict the evolutionary relationships among organisms.
• Modern classification methods use genetic data as well as morphological characteristics.

Homeostasis

• Homeostasis is the maintenance of a stable internal environment in an organism.
• This involves regulating temperature, water balance, and other internal conditions.
• Feedback mechanisms (positive and negative) play crucial roles in maintaining homeostasis.
• Examples include thermoregulation via shivering or sweating.

Explore the fundamental concepts of cell structure and the key biological molecules that sustain life. This quiz covers prokaryotic and eukaryotic cells, their organelles, and the roles of carbohydrates, lipids, proteins, and nucleic acids. Test your knowledge on how these components work together to support living organisms.