Cell Structure and Function

Cell Structure and Function

• Cells are the basic units of life, exhibiting diverse shapes and sizes, specialized for specific functions.
• Prokaryotic cells (bacteria and archaea) lack a nucleus and membrane-bound organelles; eukaryotic cells (animals, plants, fungi, and protists) possess a nucleus and various organelles.
• Animal cells include the plasma membrane, nucleus, cytoplasm, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, ribosomes, and cytoskeleton.
• Organelles perform specific tasks in maintaining cellular balance. Mitochondria produce energy; the endoplasmic reticulum synthesizes and transports proteins and lipids.
• Plant cells have unique features—a cell wall, chloroplasts, and a large central vacuole—adapted for photosynthesis and water regulation.
• Cell membranes, composed of phospholipids, proteins, and carbohydrates, control substance entry and exit.
• Cell communication involves signaling pathways allowing cell interaction and response to stimuli, vital for organismal function.

Cellular Processes

• Cellular respiration breaks down glucose to release energy as ATP (adenosine triphosphate).
• Stages include glycolysis, the Krebs cycle, and the electron transport chain.
• Photosynthesis, unique to plant cells, uses light energy to convert carbon dioxide and water into glucose and oxygen.
• Photosynthesis occurs within chloroplasts, employing chlorophyll to capture light energy.
• DNA replication copies genetic material (DNA) ensuring accurate transmission during cell division.
• Transcription synthesizes RNA from a DNA template, initiating protein synthesis.
• Translation uses RNA information to synthesize proteins.
• Meiosis produces gametes (sperm and egg) via two divisions reducing chromosome number by half.
• Mitosis creates two identical daughter cells with the same chromosome number as the parent cell, crucial for growth, repair, and asexual reproduction.
• The cell cycle, consisting of interphase and the mitotic phase, governs cell division, essential for organismal health.

Biological Molecules

• Four major biological macromolecules are carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates provide energy and structural support. Examples include monosaccharides (simple sugars), disaccharides (double sugars), and polysaccharides (complex carbohydrates).
• Lipids store energy, insulate, and form cellular structures. Types include fats, oils, phospholipids, and steroids.
• Proteins perform various functions in cells as enzymes, hormones, structural elements, and transport proteins.
• Nucleic acids store and transmit genetic information: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Evolution and Diversity of Life

• Evolution is the gradual change in heritable traits of biological populations over generations.
• Natural selection, driven by environmental pressures, favors traits enhancing survival and reproduction.
• Taxonomy categorizes organisms into hierarchical groups based on shared traits and evolutionary relationships.
• Diverse species exhibit unique adaptations and ecological roles.
• Phylogenetic trees illustrate evolutionary relationships, displaying branching patterns based on common ancestry.
• Speciation, extinction, and adaptation are fundamental concepts of life's diversity.

Ecology

• Ecology studies interactions between organisms and their environment.
• Key ecological concepts are population dynamics, community structure, and ecosystem function.
• Organisms interact in various levels forming food webs, affecting energy and nutrient flow.
• Biomes are large-scale ecological communities with specific climates and vegetation.
• Human impacts like pollution and habitat destruction affect ecological dynamics and biodiversity.