Fundamentals of Biology

• Biology explores the structure, function, growth, origin, evolution, and distribution of living organisms

Core Principles

• Cell theory states all living organisms are composed of cells
• Gene theory states hereditary information is encoded in genes and passed on to offspring
• Populations of organisms change over time through natural selection
• Homeostasis is how living organisms maintain a stable internal environment

Levels of Biological Organization

• Atoms combine to form molecules, such as DNA and proteins
• Cells, the basic unit of life, contain organelles and molecules
• Tissues are groups of similar cells performing a specific function
• Organs are structures composed of different tissues working together
• Organ systems are groups of organs that cooperate to perform major bodily functions
• Organisms are individual living entities consisting of one or more organ systems
• Populations are groups of individuals of the same species living in a specific area
• Communities are assemblages of different populations interacting with each other
• Ecosystems are communities of organisms interacting with their physical environment
• The biosphere is the sum of all ecosystems on Earth

Cell Biology

• Cells are the fundamental units of life, categorized as prokaryotic or eukaryotic
• Prokaryotic cells lack a nucleus and other membrane-bound organelles (e.g., bacteria)
• Eukaryotic cells possess a nucleus and membrane-bound organelles (e.g., plant and animal cells)
• Key organelles include the nucleus, mitochondria, ribosomes, endoplasmic reticulum (ER), golgi apparatus, and lysosomes
  • The nucleus contains the cell's genetic material (DNA)
  • Mitochondria generate energy through cellular respiration
  • Ribosomes synthesize proteins
  • The endoplasmic reticulum (ER) is involved in protein and lipid synthesis
  • The Golgi apparatus modifies, sorts, and packages proteins and lipids
  • Lysosomes contain enzymes for intracellular digestion
• The cell membrane is a selectively permeable boundary that controls the movement of substances in and out of the cell
• The cell wall, present in plant, bacterial, and fungal cells, is a rigid outer layer that provides support and protection

Genetics

• Genes are units of heredity made of DNA, carrying instructions for building proteins
• DNA (deoxyribonucleic acid) is a double-stranded molecule composed of nucleotides (adenine, guanine, cytosine, and thymine)
• RNA (ribonucleic acid) is a single-stranded molecule involved in protein synthesis (adenine, guanine, cytosine, and uracil)
• Chromosomes are structures within the nucleus made of tightly coiled DNA

Gene expression

- Transcription is where DNA is transcribed into mRNA
- Translation is where mRNA is translated into a protein at the ribosome

• Mutations are changes in the DNA sequence that can lead to genetic variation
• Inheritance is the passing of genes from parents to offspring
• Mendelian genetics includes the laws of segregation and independent assortment and are based on the work of Gregor Mendel
• Genetic engineering is the manipulation of an organism's genes through techniques like recombinant DNA technology

Evolution

• Evolution is the change in the genetic makeup of a population over time
• Natural selection is the process by which individuals with advantageous traits are more likely to survive and reproduce
• Adaptation consists of inherited traits that enhance an organism's survival and reproduction in a specific environment
• Mechanisms of evolution:
  • Mutation introduces new genetic variation
  • Gene flow is the movement of genes between populations
  • Genetic drift involves random changes in allele frequencies due to chance
  • Natural selection means differential survival and reproduction based on traits

Evidence for evolution:

- The fossil record shows the history of life on Earth
- Comparative anatomy includes similarities in anatomical structures among different species
- Embryology shows similarities in embryonic development among different species
- Molecular biology shows similarities in DNA and protein sequences among different species
- Biogeography includes the geographic distribution of species

• Speciation is the process by which new species arise from existing ones

Ecology

• Ecology is the study of the interactions between organisms and their environment
• Populations are groups of individuals of the same species living in a specific area
• Communities are assemblages of different populations interacting with each other
• Ecosystems are communities of organisms interacting with their physical environment
• Biosphere represents the sum of all ecosystems on Earth

Key ecological concepts:

- Food chains and food webs illustrate the flow of energy and nutrients through ecosystems
- Trophic levels refer to an organism's position in a food chain (e.g., producers, consumers, decomposers)
- Nutrient cycles are the movement of essential elements (e.g., carbon, nitrogen, phosphorus) through ecosystems
- Population dynamics are factors that influence population size and growth
- Community structure is the composition and organization of species within a community
- Succession is the process of ecological change in a community over time

• Biomes are large-scale ecosystems characterized by specific climate conditions and dominant vegetation types

Botany

• Botany is the scientific study of plants
• Plant cells are eukaryotic cells with unique structures like chloroplasts and cell walls
• Photosynthesis is the process by which plants convert light energy into chemical energy (glucose)

Plant tissues:

- Dermal tissue is the outer protective layer
- Ground tissue fills the interior of the plant and performs various functions (e.g., photosynthesis, storage)
- Vascular tissue transports water and nutrients throughout the plant (xylem and phloem)

Plant organs:

- Roots anchor the plant and absorb water and nutrients
- Stems support the plant and transport water and nutrients
- Leaves are the primary site of photosynthesis
- Flowers are involved in reproduction

Plant reproduction:

- Sexual reproduction involves the fusion of gametes (pollen and ovule)
- Asexual reproduction does not involve the fusion of gametes (e.g., vegetative propagation)

• Plant classification is based on evolutionary relationships (e.g., bryophytes, ferns, gymnosperms, angiosperms)

Zoology

• Zoology is the scientific study of animals
• Animal cells are eukaryotic cells lacking cell walls and chloroplasts

Animal tissues:

- Epithelial tissue covers body surfaces and lines internal organs
- Connective tissue supports, connects, and separates different types of tissues and organs in the body
- Muscle tissue is responsible for movement
- Nervous tissue transmits electrical signals

Animal organ systems:

- The digestive system breaks down food and absorbs nutrients
- The respiratory system exchanges gases (oxygen and carbon dioxide)
- The circulatory system transports blood, oxygen, and nutrients throughout the body
- The excretory system removes waste products
- The nervous system coordinates bodily functions and responses to stimuli
- The endocrine system produces hormones that regulate bodily functions
- The skeletal system provides support and protection
- The muscular system enables movement
- The reproductive system is involved in reproduction
- The immune system protects the body from pathogens

• Animal classification is based on evolutionary relationships (e.g., invertebrates, vertebrates)

Microbiology

• Microbiology is the study of microorganisms, including bacteria, archaea, viruses, fungi, and protozoa
• Bacteria are prokaryotic cells with diverse metabolic capabilities
• Archaea are prokaryotic cells that are genetically and biochemically distinct from bacteria
• Viruses are non-cellular entities that require a host cell to replicate
• Fungi are eukaryotic heterotrophs that obtain nutrients by absorption
• Protozoa are eukaryotic unicellular organisms with diverse feeding strategies

Importance of microorganisms:

- Nutrient cycling is how they decompose organic matter and recycle nutrients
- Biotechnology uses them in the production of antibiotics, biofuels, and other products
- Human health is impacted as some are beneficial (e.g., gut microbes) while others are pathogenic (disease-causing)

Human Biology

• Human biology focuses on the structure, function, and evolution of the human body
• Anatomy studies the structure of the human body
• Physiology studies the function of the human body

Key organ systems:

- The skeletal system provides support and protection
- The muscular system enables movement
- The nervous system coordinates bodily functions and responses to stimuli
- The endocrine system produces hormones that regulate bodily functions
- The cardiovascular system transports blood, oxygen, and nutrients
- The respiratory system exchanges gases (oxygen and carbon dioxide)
- The digestive system breaks down food and absorbs nutrients
- The urinary system removes waste products
- The immune system protects the body from pathogens
- The reproductive system enables reproduction

• Human genetics studies genes, heredity, and genetic variation in humans
• Human evolution refers to the evolutionary history of humans, including our relationship to other primates and the origins of modern humans