Introduction to Biology

• Biology is the scientific study of life and living organisms.
• It explores the structure, function, growth, origin, evolution, and distribution of living things.
• It is a broad field comprising many specialized disciplines such as anatomy, botany, zoology, and microbiology.

Core Principles

• Cell theory states that the cell is the basic unit of life.
• Genes, made of DNA, are the basic units of heredity.
• Evolution explains the unity and diversity of life.
• Homeostasis refers to maintaining a stable internal environment.

Branches of Biology

• Biochemistry studies the chemical processes within and relating to living organisms.
• Molecular biology studies the structure and function of macromolecules essential to life.
• Genetics studies heredity and variation of inherited characteristics.
• Microbiology studies microorganisms, including bacteria, viruses, fungi, and protozoa.
• Botany studies plants, including their physiology, structure, genetics, and ecology.
• Zoology studies animals, including their behavior, physiology, structure, and classification.
• Ecology studies the interactions between organisms and their environment.
• Anatomy studies the structure of organisms and their parts.
• Physiology studies the functions and mechanisms in a living system.

Cell Biology

• Cells are the fundamental units of life, capable of carrying out all life processes.
• Eukaryotic cells have a nucleus and other membrane-bound organelles.
• Prokaryotic cells lack a nucleus and other membrane-bound organelles.
• The plasma membrane is a selective barrier that regulates the passage of substances in and out of the cell.
• The nucleus contains the cell's genetic material (DNA).
• Ribosomes are responsible for protein synthesis.
• Mitochondria are the powerhouses of the cell, producing ATP through cellular respiration.
• Chloroplasts (in plant cells) are the sites of photosynthesis.
• The endoplasmic reticulum (ER) is involved in protein and lipid synthesis.
• The Golgi apparatus processes and packages proteins.
• Lysosomes contain enzymes for intracellular digestion.

Genetics

• Genes are the units of heredity composed of DNA.
• DNA (deoxyribonucleic acid) is the molecule that carries genetic information.
• Chromosomes are structures within cells that contain DNA.
• Genotype refers to the genetic makeup of an organism.
• Phenotype refers to the observable characteristics of an organism.
• DNA replication is the process of copying DNA.
• Transcription is the process of synthesizing RNA from a DNA template.
• Translation is the process of synthesizing proteins from an RNA template.
• Mutations are changes in the DNA sequence.
• Mendelian genetics describes the principles of inheritance.

Evolution

• Evolution is the change in the heritable characteristics of biological populations over successive generations.
• Natural selection is the process by which organisms better adapted to their environment tend to survive and reproduce more successfully.
• Adaptation is the process by which organisms become better suited to their environment.
• Speciation is the process by which new species arise.
• Evidence for evolution includes fossil records, comparative anatomy, and molecular biology.

Ecology

• Ecology is the study of the interactions between organisms and their environment.
• An ecosystem is a community of living organisms and their physical environment.
• A population is a group of individuals of the same species living in the same area.
• A community is a group of interacting populations of different species.
• The biosphere is the global sum of all ecosystems.
• Trophic levels describe the position of an organism in a food chain or food web.
• Energy flow describes the transfer of energy through an ecosystem.
• Nutrient cycles describe the movement of essential elements (e.g., carbon, nitrogen, phosphorus) through an ecosystem.
• Biomes are large geographic areas characterized by specific climate conditions, animal populations, and plant species.

Plant Biology

• Plants are multicellular, eukaryotic organisms in the kingdom Plantae.
• Photosynthesis is the process by which plants convert light energy into chemical energy.
• Plant cells have cell walls made of cellulose.
• Vascular tissues (xylem and phloem) transport water and nutrients throughout the plant.
• Roots anchor the plant and absorb water and nutrients from the soil.
• Stems provide support and transport materials between roots and leaves.
• Leaves are the primary sites of photosynthesis.
• Flowers are the reproductive structures of angiosperms (flowering plants).
• Plant hormones regulate growth and development.

Animal Biology

• Animals are multicellular, eukaryotic organisms in the kingdom Animalia.
• Animal cells lack cell walls.
• Animals are heterotrophic, meaning they obtain nutrients by consuming other organisms.
• 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 working together to perform a major function.
• Animals exhibit a wide range of body plans and adaptations.
• Reproduction can be sexual or asexual.
• Nervous systems coordinate bodily functions and responses to stimuli.
• Endocrine systems regulate physiological processes through hormones.

Microbiology

• Microorganisms are microscopic organisms, including bacteria, viruses, fungi, and protozoa.
• Bacteria are prokaryotic cells.
• Viruses are noncellular entities that require a host cell to replicate.
• Fungi are eukaryotic organisms with cell walls made of chitin.
• Protozoa are unicellular, eukaryotic organisms.
• Microorganisms play important roles in nutrient cycling, decomposition, and disease.
• Some microorganisms are used in biotechnology and industrial processes.

Biochemistry

• Biochemistry is the study of the chemical processes within and relating to living organisms.
• Carbohydrates are the primary source of energy for cells.
• Lipids (fats) are important for energy storage, insulation, and cell membrane structure.
• Proteins are involved in a wide range of functions, including enzyme catalysis, structural support, and transport.
• Nucleic acids (DNA and RNA) carry genetic information.
• Enzymes are biological catalysts that speed up chemical reactions.
• Metabolism is the sum of all chemical reactions that occur in an organism.

Scientific Method

• Observation: Observing a phenomenon or identifying a problem.
• Hypothesis: Formulating a testable explanation for the observation.
• Experimentation: Designing and conducting experiments to test the hypothesis.
• Data Analysis: Analyzing the results of the experiment.
• Conclusion: Drawing conclusions based on the data and determining whether the hypothesis is supported or refuted.
• Communication: Sharing the findings with the scientific community.

Tools and Techniques

• Microscopy: Using microscopes to visualize cells and other microscopic structures.
• Cell culture: Growing cells in a controlled environment.
• DNA sequencing: Determining the nucleotide sequence of DNA.
• Gel electrophoresis: Separating molecules based on size and charge.
• Spectrophotometry: Measuring the absorbance and transmission of light through a sample.
• Polymerase chain reaction (PCR): Amplifying specific DNA sequences.

Important Concepts

• Homeostasis: Maintenance of a stable internal environment.
• Cellular respiration: Process of converting glucose into ATP (energy).
• Photosynthesis: Process of converting light energy into chemical energy (glucose).
• Enzyme: A biological catalyst that speeds up chemical reactions.
• Gene expression: The process by which information encoded in a gene is used to synthesize a functional gene product (protein or RNA).
• Biodiversity: The variety of life in the world or in a particular habitat or ecosystem.