Fundamentals of Biology

• Biology is the scientific study of life.
• It explores the structure, function, growth, origin, evolution, and distribution of living organisms.
• Central themes in biology include cell theory, gene theory, evolution, homeostasis, and energy.

Cell Theory

• The cell is the basic unit of life.
• All living organisms are composed of one or more cells.
• All cells arise from pre-existing cells.

Gene Theory

• Genes are the basic units of heredity.
• Genes are composed of DNA.
• Genes provide the instructions for the structure and function of cells.
• Genes are passed from parents to offspring.

Evolution

• Evolution is the change in the heritable characteristics of biological populations over successive generations.
• Natural selection is a primary mechanism of evolution, where traits that enhance survival and reproduction become more common in a population over time.
• Evolution explains the diversity of life on Earth and the relationships between different species.

Homeostasis

• Homeostasis is the ability of an organism to maintain a stable internal environment despite changes in the external environment.
• Homeostasis involves regulatory mechanisms that maintain temperature, pH, and other internal conditions within a narrow range.
• Feedback loops are essential for maintaining homeostasis.

Energy

• All living organisms require energy to carry out life processes.
• The sun is the primary source of energy for life on Earth.
• Photosynthesis is the process by which plants and other organisms convert light energy into chemical energy in the form of glucose.
• Cellular respiration is the process by which cells break down glucose to release energy in the form of ATP.
• ATP (adenosine triphosphate) is the primary energy currency of cells.

Levels of Biological Organization

• Life can be organized into a hierarchy of levels, from atoms to the biosphere
• These levels include: molecules, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, and the biosphere.
• Each level builds upon the previous one and exhibits emergent properties.

Biomolecules

• Organic molecules are the building blocks of life, and they are carbon-based.
• The four major classes of biomolecules are carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates provide energy and structural support e.g. sugars and starches.
• Lipids include fats, oils, and phospholipids; for energy storage, insulation, and cell membrane structure.
• Proteins perform a wide variety of functions, including catalysis, transport, and structural support.
• Nucleic acids (DNA and RNA) store and transmit genetic information.

Cell Structure and Function

• Cells are the fundamental units of life and can be prokaryotic or eukaryotic.
• Prokaryotic cells (bacteria and archaea) lack a nucleus and other membrane-bound organelles.
• Eukaryotic cells (plants, animals, fungi, and protists) have a nucleus and other membrane-bound organelles.
• The nucleus contains the cell's DNA and controls cell activities.
• The cell membrane is the outer boundary of the cell, regulating the movement of substances in and out.
• Organelles such as mitochondria, chloroplasts, ribosomes, and endoplasmic reticulum perform specific functions within the cell.

Genetics

• Genetics is the study of heredity and variation.
• Chromosomes are structures within the nucleus that carry genes.
• DNA is organized into genes, which code for specific traits.
• Genotype refers to the genetic makeup of an organism, while phenotype refers to its observable characteristics.
• Genetic variation arises through mutation, recombination, and other processes.
• Mendelian genetics describes the basic principles of inheritance, including segregation and independent assortment.

Molecular Biology

• Molecular biology focuses on the structure and function of biological molecules, such as DNA, RNA, and proteins.
• DNA replication is the process by which DNA is copied.
• Transcription is the process by which RNA is synthesized from a DNA template.
• Translation is the process by which proteins are synthesized from an RNA template.
• The central dogma of molecular biology describes the flow of genetic information from DNA to RNA to protein.

Evolution and Diversity

• Evolution is the process by which populations of organisms change over time.
• Natural selection is a primary mechanism of evolution, where individuals with advantageous traits are more likely to survive and reproduce.
• Adaptation is the process by which organisms become better suited to their environment through evolution.
• Species are groups of organisms that can interbreed and produce fertile offspring.
• Biodiversity refers to the variety of life on Earth.

Ecology

• Ecology is the study of the interactions between organisms and their environment.
• Populations are groups of individuals of the same species living in the same area.
• Communities are groups of interacting populations of different species.
• Ecosystems are communities of organisms interacting with their physical environment.
• The biosphere is the sum of all ecosystems on Earth.
• Energy flows through ecosystems from producers to consumers to decomposers.
• Nutrient cycles, such as the carbon cycle and nitrogen cycle, involve the movement of nutrients through ecosystems.

Plant Biology

• Plants are multicellular, eukaryotic organisms that are characterized by their ability to perform photosynthesis.
• Plant cells have unique structures, such as cell walls, chloroplasts, and large central vacuoles.
• Photosynthesis is the process by which plants convert light energy into chemical energy in the form of glucose.
• Plant transport systems, such as xylem and phloem, transport water, nutrients, and sugars throughout the plant.
• Plant reproduction can be sexual or asexual.

Animal Biology

• Animals are multicellular, eukaryotic organisms that are characterized by their heterotrophic mode of nutrition.
• Animal cells lack cell walls and have specialized tissues, such as muscle tissue and nervous tissue.
• Animal organ systems, such as the digestive system, circulatory system, and nervous system, perform specific functions within the body.
• Animal reproduction is typically sexual.

Microbiology

• Microbiology is the study of microorganisms, such as bacteria, archaea, viruses, fungi, and protists.
• Microorganisms play important roles in nutrient cycling, decomposition, and disease.
• Bacteria and archaea are prokaryotic organisms that are found in diverse environments.
• Viruses are non-cellular entities that can infect cells and cause disease.
• Fungi are eukaryotic organisms that can be unicellular or multicellular.
• Protists are a diverse group of eukaryotic organisms, including algae and protozoa.

Overview of biology, the study of life, including cell theory, gene theory, evolution, homeostasis, and energy. It covers the structure, function, growth, origin, evolution, and distribution of living organisms. Key principles and concepts in biology are explained.