Cell Structure and Function

Cell Structure and Function

• Cells are the basic units of life, varying greatly in shape and size.
• All cells share fundamental features: a plasma membrane, cytoplasm, and genetic material (DNA).
• Prokaryotic cells (bacteria and archaea) lack a nucleus and membrane-bound organelles.
• Eukaryotic cells (animals, plants, fungi, and protists) possess a nucleus and various membrane-bound organelles, including mitochondria, endoplasmic reticulum, Golgi apparatus, and chloroplasts (in plant cells).

Cellular Processes

• Cellular respiration breaks down glucose to produce ATP, the cell's primary energy source.
• Photosynthesis, unique to plant cells, converts light energy into glucose.
• DNA replication ensures accurate genetic material duplication during cell division.
• Protein synthesis involves transcription (DNA to RNA) and translation (RNA to protein).
• Cell division (mitosis and meiosis) is crucial for growth, repair, and reproduction. Mitosis creates identical daughter cells, while meiosis forms genetically diverse gametes.

Principles of Inheritance

• Genes are DNA segments directing protein production.
• Alleles are different forms of a gene.
• The principle of segregation dictates each gamete receives one allele per gene.
• The principle of independent assortment means alleles for different genes segregate independently.
• Mendel's laws explain trait inheritance from parents to offspring.
• Mutations are DNA sequence changes causing trait variations.

Diversity of Life

• Organisms are classified into three domains: Bacteria, Archaea, and Eukarya.
• Each domain encompasses various kingdoms.
• Biological diversity is the variety of life forms across all levels, from genes to ecosystems.
• Evolution is species change through time, driven by natural selection.

Ecology

• Organisms interact intricately with their environments.
• Ecosystems comprise biotic (living) and abiotic (non-living) factors.
• Food webs illustrate energy and nutrient flow in ecosystems.
• Biodiversity is life variety within a specific region or ecosystem.
• Predation, competition, and symbiosis shape ecosystems.

Physiology

• Organisms maintain homeostasis through physiological processes.
• Examples include regulating human body temperature, blood pressure, and pH.
• The human circulatory system transports oxygen and nutrients.
• The nervous system enables communication and coordination.
• The respiratory system facilitates gas exchange.

Mechanisms of Disease

• Disease arises from pathogens (bacteria, viruses, fungi), genetic defects, and environmental factors.
• The immune system defends the body against pathogens.
• Injury response involves inflammation and repair processes.

Plant Biology

• Plants perform essential functions, including photosynthesis and maintaining the environment.
• Root, stem, and leaf structures perform specialized roles.
• Plant reproduction involves flower, seed, and fruit formation.