Biological Classification and Cell Structure

Biological Classification

• Organisms are categorized into various groups based on shared characteristics, reflecting evolutionary relationships.
• The hierarchical system of classification includes domains, kingdoms, phyla, classes, orders, families, genera, and species.
• Domain is the broadest category, encompassing Bacteria, Archaea, and Eukarya.
• Kingdoms are major subdivisions within domains. E.g., Animalia, Plantae, Fungi.
• Each subsequent level refines the characteristics shared by organisms.
• Binomial nomenclature, using genus and species names, is a standardized system for naming organisms.

Cell Structure and Function

• Cells are the basic structural and functional units of life.
• Prokaryotic cells, like bacteria, lack a nucleus and membrane-bound organelles.
• Eukaryotic cells, found in plants, animals, fungi, and protists, possess a nucleus and membrane-bound organelles like mitochondria and chloroplasts.
• Plasma membrane surrounds the cell, controlling what enters and exits.
• Cell walls are found in plant and fungal cells, providing support and structure.
• Cytoplasm is the jelly-like substance inside cells.
• Nucleus contains the genetic material (DNA), controlling cellular activities.
• Mitochondria are the powerhouses of cells, responsible for cellular respiration.
• Chloroplasts are present in plant cells and perform photosynthesis.

Metabolism

• Metabolism is the sum of chemical reactions in an organism to maintain life.
• Catabolism breaks down complex molecules into simpler ones, releasing energy.
• Anabolism builds complex molecules from simpler ones, requiring energy.
• Cellular respiration is a catabolic process that breaks down glucose to produce ATP (energy).
• Photosynthesis is an anabolic process used by plants to produce glucose from sunlight, water, and carbon dioxide.

Genetics

• Genes are segments of DNA that carry the instructions for building proteins.
• DNA replication ensures accurate duplication of genetic material.
• DNA transcription converts genetic information from DNA to RNA.
• Translation uses RNA to synthesize proteins.
• Mutations are changes in DNA sequence, which can lead to altered proteins and potentially new traits.
• Inheritance patterns, such as Mendelian genetics and non-Mendelian genetics, describe how traits are passed from parents to offspring.

Evolution

• Evolution explains how life has changed over time.
• Natural selection is a driving force in evolution, favoring advantageous traits.
• Adaptation is the process where organisms acquire traits that improve survival and reproduction in their environment.
• Common ancestry connects different species, with shared evolutionary origins.
• Speciation is the formation of new species from pre-existing ones.

Ecology

• Ecology studies the interactions between organisms and their environment.
• Key ecological concepts include ecosystems, habitats, populations, communities, and biomes.
• Food chains and food webs describe energy flow through ecosystems.
• Nutrient cycling (e.g., carbon cycle, nitrogen cycle) is essential for ecosystem functions.
• Human impact on ecosystems, such as pollution, deforestation, and climate change, is a major concern.

Biological diversity

• Biodiversity is the variety of life on Earth at all levels, from genes to ecosystems.
• High biodiversity is important for ecosystem health and stability.
• Threats to biodiversity include habitat destruction, pollution, and climate change.
• Conservation efforts aim to protect and preserve biodiversity.