Introduction to Biology

Biology

• Biology is the scientific study of life.
• It explores the structure, function, growth, origin, evolution, and distribution of living organisms.
• Biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the creation and extinction of species.
• Living organisms are open systems that survive by transforming energy and decreasing their local entropy.

Branches of Biology

• Biochemistry examines the fundamental chemistry of life, studying the structure and function of biomolecules.
• Molecular biology studies the interactions between various systems of a cell, including the relationships between DNA, RNA, and protein synthesis.
• Botany is the scientific study of plants.
• Microbiology studies microorganisms including bacteria, archaea, fungi, protists, and viruses.
• Zoology is the study of animals, including their classification, physiology, behavior, and ecology.
• Genetics studies heredity and variation in organisms.
• Ecology studies the interactions of organisms with each other and their environment
• Evolutionary biology studies the processes that have led to the diversity of life on Earth.
• Physiology studies the function of living organisms and their parts.

Cell Biology

• The cell is the basic unit of life.
• Cell theory states that all living organisms are composed of cells, and that all cells arise from pre-existing cells.
• Cells are classified as either prokaryotic (lacking a nucleus) or eukaryotic (possessing a nucleus).
• Key organelles in eukaryotic cells include the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles.
• The plasma membrane surrounds the cell and regulates the movement of substances in and out.
• Cellular processes include cell division (mitosis and meiosis), cellular respiration, and protein synthesis.

Genetics

• Genes are the basic units of heredity and are composed of DNA.
• DNA (deoxyribonucleic acid) is a double-stranded molecule that carries the genetic instructions for all known living organisms.
• RNA (ribonucleic acid) is a single-stranded molecule involved in protein synthesis.
• The central dogma of molecular biology describes the flow of genetic information: DNA -> RNA -> Protein.
• Genetic inheritance follows the principles established by Gregor Mendel, including the laws of segregation and independent assortment.
• Mutations are changes in the DNA sequence and can be spontaneous or induced by external factors.
• Genetic engineering involves the manipulation of an organism's genes to introduce or eliminate specific traits.

Evolution

• Evolution is the change in the heritable characteristics of biological populations over successive generations.
• Natural selection is the primary mechanism of evolution, where individuals with advantageous traits are more likely to survive and reproduce.
• Evidence for evolution includes the fossil record, comparative anatomy, embryology, and molecular biology.
• Charles Darwin proposed the theory of evolution by natural selection in his book "On the Origin of Species."
• Adaptation is the process by which organisms become better suited to their environment through evolution.
• Speciation is the process by which new species arise from existing species through reproductive isolation and genetic divergence.

Ecology

• Ecology is the study of the interactions between organisms and their environment.
• Ecosystems are communities of living organisms interacting with their physical environment.
• Biomes are large-scale ecosystems characterized by specific climate conditions and dominant plant communities.
• Populations are groups of individuals of the same species living in the same area.
• Communities are groups of different species living in the same area and interacting with each other.
• Food chains and food webs describe the flow of energy and nutrients through an ecosystem.
• Trophic levels represent the position of an organism in a food chain or food web.
• Ecological succession is the process of change in the species structure of an ecological community over time.

Plant Biology

• Plants are multicellular, eukaryotic organisms that belong to the Kingdom Plantae.
• Plants use photosynthesis to convert light energy into chemical energy in the form of glucose.
• The main parts of a plant include the roots, stem, leaves, and reproductive structures (flowers, cones).
• Plant tissues include dermal tissue, vascular tissue (xylem and phloem), and ground tissue.
• Plant reproduction can be sexual (involving flowers and seeds) or asexual (vegetative propagation).
• Plant hormones regulate growth, development, and responses to environmental stimuli.

Animal Biology

• Animals are multicellular, eukaryotic organisms that belong to the Kingdom Animalia.
• Animals are heterotrophs, meaning they obtain nutrients by consuming other organisms.
• Animals are classified into various phyla, including chordates (animals with a backbone), arthropods (insects, crustaceans), mollusks (snails, clams), and echinoderms (starfish, sea urchins).
• Animal physiology includes the study of organ systems such as the circulatory, respiratory, digestive, nervous, and endocrine systems.
• Animal behavior is the study of how animals interact with each other and their environment.
• Animal reproduction can be sexual or asexual, and involves various strategies such as external fertilization, internal fertilization, and metamorphosis.

Microbiology

• Microbiology is the study of microorganisms, including bacteria, archaea, fungi, protists, and viruses.
• Microorganisms are ubiquitous and play important roles in various ecosystems and human health.
• Bacteria and archaea are prokaryotic organisms with diverse metabolic capabilities.
• Fungi are eukaryotic organisms that can be unicellular (yeasts) or multicellular (molds).
• Protists are a diverse group of eukaryotic microorganisms that are not plants, animals, or fungi.
• Viruses are non-cellular entities that require a host cell to replicate.
• Microorganisms can be beneficial (e.g., in food production, nutrient cycling) or harmful (e.g., causing diseases).

Human Biology

• Human biology is the study of the human body, including its structure, function, and interactions with the environment.
• The human body is composed of various organ systems that work together to maintain homeostasis.
• The skeletal system provides support and protection.
• The muscular system enables movement.
• The nervous system controls and coordinates bodily functions.
• The endocrine system regulates hormone production.
• The circulatory system transports blood, oxygen, and nutrients.
• The respiratory system facilitates gas exchange.
• The digestive system breaks down food and absorbs nutrients.
• The urinary system eliminates waste products.
• The immune system defends against pathogens.
• Human reproduction involves sexual reproduction and development.

Biochemistry

• Biochemistry explores the chemical processes within and relating to living organisms.
• Key biomolecules include carbohydrates, lipids, proteins, and nucleic acids.
• Enzymes are biological catalysts that speed up chemical reactions in living organisms.
• Metabolism is the sum of all chemical reactions that occur in a living organism, including anabolism (building up molecules) and catabolism (breaking down molecules).
• Cellular respiration is the process by which cells generate energy in the form of ATP (adenosine triphosphate) from glucose and other organic molecules.
• Photosynthesis is the process by which plants use light energy to convert carbon dioxide and water into glucose.
• Protein synthesis involves the transcription of DNA into RNA and the translation of RNA into proteins.
• Nucleic acids (DNA and RNA) carry genetic information and play a crucial role in heredity and protein synthesis.