Introduction to Biology: Core Principles and Chemistry

• Biology is the scientific study of life
• It explores the structure, function, growth, origin, evolution, and distribution of living organisms

Core Principles of Biology

• Cell theory: All living organisms are composed of cells
• The cell is the basic unit of structure and function in organisms
• All cells arise from pre-existing cells
• Gene theory: Characteristics are inherited through genes
• Genes are located on chromosomes and consist of DNA
• Evolution: Life evolves over time through processes like natural selection
• Natural selection is the differential survival and reproduction of individuals due to differences in phenotype
• Homeostasis: Living organisms maintain a stable internal environment
• This is achieved through various regulatory mechanisms

Chemical Basis of Life

• Living organisms are composed of organic molecules
• Carbohydrates, lipids, proteins, and nucleic acids
• Water is essential for life
• It is an excellent solvent, has a high heat capacity, and participates in many biochemical reactions
• Carbon is the backbone of organic molecules
• It can form stable bonds with many other elements, including hydrogen, oxygen, nitrogen, phosphorus, and sulfur

Cell Structure and Function

• Prokaryotic cells lack a nucleus and other membrane-bound organelles
• Bacteria and Archaea
• Eukaryotic cells have a nucleus and other membrane-bound organelles
• Protists, fungi, plants, and animals
• The plasma membrane surrounds the cell and regulates the movement of substances in and out
• The nucleus contains the cell's DNA and controls the cell's activities
• Ribosomes are responsible for protein synthesis
• The endoplasmic reticulum (ER) is involved in protein and lipid synthesis
• The Golgi apparatus modifies, sorts, and packages proteins and lipids
• Mitochondria are responsible for cellular respiration
• They generate ATP, the cell's primary energy currency
• Chloroplasts are responsible for photosynthesis in plants and algae
• They convert light energy into chemical energy
• Lysosomes contain enzymes that break down cellular waste and debris

Energy and Metabolism

• Metabolism is the sum of all chemical reactions in an organism
• Anabolism is the synthesis of complex molecules from simpler ones
• It requires energy
• Catabolism is the breakdown of complex molecules into simpler ones
• It releases energy
• Enzymes are biological catalysts that speed up chemical reactions
• ATP (adenosine triphosphate) is the primary energy currency of cells
• Cellular respiration is the process by which cells break down glucose to produce ATP
• Glycolysis, Krebs cycle, and electron transport chain
• Photosynthesis is the process by which plants and algae convert light energy into chemical energy
• Light-dependent reactions and Calvin cycle

Genetics

• DNA (deoxyribonucleic acid) is the genetic material of all living organisms (except some viruses)
• It is a double helix composed of nucleotides
• RNA (ribonucleic acid) is involved in protein synthesis
• mRNA, tRNA, and rRNA
• Genes are segments of DNA that encode proteins
• The genome is the complete set of genes in an organism
• DNA replication is the process by which DNA is copied
• Transcription is the process by which RNA is synthesized from DNA
• Translation is the process by which proteins are synthesized from RNA
• Mutations are changes in the DNA sequence
• They can be spontaneous or caused by mutagens
• Genetic engineering is the manipulation of genes for practical purposes

Evolution

• Evolution is the change in the genetic makeup of a population over time
• Natural selection is the driving force of evolution
• Adaptations are traits that increase an organism's survival and reproduction
• Speciation is the process by which new species arise
• Allopatric and sympatric speciation
• Evidence for evolution includes the fossil record, comparative anatomy, embryology, and molecular biology

Diversity of Life

• The three domains of life are Bacteria, Archaea, and Eukarya
• Bacteria are prokaryotic organisms that lack a nucleus and other membrane-bound organelles
• Archaea are prokaryotic organisms that are often found in extreme environments
• Eukarya are eukaryotic organisms that have a nucleus and other membrane-bound organelles
• Protists, fungi, plants, and animals
• Viruses are not considered living organisms
• They require a host cell to replicate

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 different populations living in the same area
• Ecosystems are communities of organisms and their physical environment
• The biosphere is the sum of all ecosystems on Earth
• Food chains and food webs describe the flow of energy through an ecosystem
• Trophic levels represent the different feeding levels in an ecosystem
• Producers, consumers, and decomposers
• Biogeochemical cycles describe the movement of elements through ecosystems
• Carbon, nitrogen, and water cycles
• Human activities have a significant impact on the environment
• Pollution, deforestation, and climate change

Plant Biology

• Plants are multicellular, eukaryotic organisms that are autotrophic
• They produce their own food through photosynthesis
• Plant cells have cell walls made of cellulose
• Plants have specialized tissues and organs
• Roots, stems, leaves, flowers, fruits, and seeds
• Vascular plants have vascular tissue
• Xylem and phloem
• Non-vascular plants lack vascular tissue
• Mosses, liverworts, and hornworts
• Plant reproduction can be sexual or asexual
• Plant hormones regulate plant growth and development

Animal Biology

• Animals are multicellular, eukaryotic organisms that are heterotrophic
• They obtain their food by consuming other organisms
• Animal cells lack cell walls
• Animals have specialized tissues and organs
• Epithelial, connective, muscle, and nervous tissues
• Vertebrates have a backbone
• Fish, amphibians, reptiles, birds, and mammals
• Invertebrates lack a backbone
• Insects, worms, and mollusks
• Animal reproduction is typically sexual
• Animal behavior is influenced by genetics and environment

Human Biology

• Humans are mammals with complex organ systems
• The human body is composed of cells, tissues, organs, and organ systems
• The digestive system breaks down food and absorbs nutrients
• The respiratory system exchanges gases with the environment
• The circulatory system transports blood, oxygen, and nutrients throughout the body
• The nervous system controls and coordinates body functions
• The endocrine system produces hormones that regulate body functions
• The immune system protects the body from disease
• Human reproduction is sexual
• Human health is influenced by genetics, environment, and lifestyle factors

Microbiology

• Microbiology is the study of microorganisms
• Bacteria, archaea, viruses, fungi, and protists
• Microorganisms play important roles in the environment
• Decomposition, nutrient cycling, and bioremediation
• Microorganisms can cause disease
• Pathogens
• The human microbiome is the collection of microorganisms that live in and on the human body

An overview of biology, the study of life, covering core principles like cell theory, gene theory, evolution, and homeostasis. It also explores the chemical basis of life, including organic molecules and the importance of water.