Introduction to Biology Overview

Definition: The study of life and living organisms, encompassing various fields and levels of organization.
Branches of Biology:
- Molecular Biology: Study of biological molecules and their interactions.
- Cell Biology: Examination of the structure and function of cells.
- Genetics: Study of heredity, genes, and genetic variation.
- Evolutionary Biology: Understanding the origins and changes in species over time.
- Ecology: Study of interactions between organisms and their environment.
- Physiology: Study of the functions and mechanisms in living organisms.

Cell Theory:
- All living organisms are composed of cells.
- The cell is the basic unit of life.
- All cells arise from pre-existing cells.
Homeostasis:
- The maintenance of stable internal conditions despite external changes.
Metabolism:
- Sum of all chemical reactions in a living organism.
- Divided into anabolism (building up) and catabolism (breaking down).
Evolution:
- Process by which populations change over generations through natural selection and genetic drift.

Taxonomy: The science of classifying organisms.
- Hierarchy: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species.
- Domains: Bacteria, Archaea, Eukarya.

Prokaryotic Cells:
- Lack a nucleus and membrane-bound organelles.
- Examples: Bacteria and Archaea.
Eukaryotic Cells:
- Have a nucleus and membrane-bound organelles.
- Examples: Plants, animals, fungi, and protists.

DNA Structure: Double helix composed of nucleotides (adenine, thymine, cytosine, guanine).
Gene: Segment of DNA that codes for a protein.
Chromosomes: Structures made of DNA and proteins; humans have 46 chromosomes (23 pairs).

Ecosystem: Community of living organisms and their physical environment.
Biomes: Large regions characterized by specific climate and vegetation (e.g., desert, rainforest).
Food Chains and Webs: Show energy flow and feeding relationships in ecosystems.

Systems:
- Nervous System: Controls body functions through signaling.
- Circulatory System: Transports nutrients, gases, and waste.
- Respiratory System: Responsible for gas exchange (oxygen and carbon dioxide).
- Digestive System: Breaks down food for nutrient absorption.

Photosynthesis: Process by which plants convert sunlight into chemical energy (glucose) using carbon dioxide and water.
Cellular Respiration: Process of converting glucose and oxygen into energy (ATP), carbon dioxide, and water.

Biotechnology: Use of biological processes for industrial, medical, and agricultural applications.
Genomics: Study of genomes, including sequencing and functional analysis of genes.
Conservation Biology: Focus on protecting biodiversity and ecosystems.

Charles Darwin: Developed the theory of evolution by natural selection.
Gregor Mendel: Father of modern genetics; known for his work on inheritance patterns in pea plants.
James Watson and Francis Crick: Discovered the structure of DNA.

Study of life and living organisms, encompassing multiple branches and organization levels.
Branches include:
- Molecular Biology: Analyzes biological molecules and their interactions.
- Cell Biology: Investigates cell structure and function.
- Genetics: Focuses on heredity, genes, and genetic variations.
- Evolutionary Biology: Examines origins and changes in species over time.
- Ecology: Studies interactions between organisms and their environments.
- Physiology: Explores the functions and mechanisms of living organisms.

Cell Theory:
- All living organisms consist of cells.
- The cell serves as the basic unit of life.
- Cells originate from pre-existing cells.
Homeostasis:
- The ability to maintain stable internal conditions despite external fluctuations.
Metabolism:
- Total of all biochemical reactions; includes anabolism (building up) and catabolism (breaking down).
Evolution:
- Populations undergo changes through natural selection and genetic drift over generations.

Taxonomy:
- The science dedicated to classifying organisms systematically.
Hierarchical Structure:
- Organization levels: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species.
Three Domains:
- Bacteria, Archaea, and Eukarya.

Prokaryotic Cells:
- Lack a true nucleus and membrane-bound organelles; examples include Bacteria and Archaea.
Eukaryotic Cells:
- Contain a nucleus and membrane-bound organelles; examples are found in plants, animals, fungi, and protists.

DNA Structure:
- Consists of a double helix formed by nucleotides: adenine, thymine, cytosine, and guanine.
Gene:
- A DNA segment that encodes a specific protein.
Chromosomes:
- Composed of DNA and proteins; humans possess 46 chromosomes arranged in 23 pairs.

Ecosystem:
- A community of living organisms interacting with their physical environment.
Biomes:
- Large ecological areas with specific climates and vegetation, like deserts and rainforests.
Food Chains and Webs:
- Illustrate the flow of energy and feeding relationships in ecosystems.

Major Systems:
- Nervous System: Regulates body functions through signaling.
- Circulatory System: Transports nutrients, gases, and wastes.
- Respiratory System: Facilitates gas exchange (oxygen and carbon dioxide).
- Digestive System: Breaks down food for nutrient absorption.

Photosynthesis:
- Plants transform sunlight into chemical energy (glucose) using carbon dioxide and water.
Cellular Respiration:
- Converts glucose and oxygen into energy (ATP), carbon dioxide, and water.

Biotechnology:
- Involves using biological processes for industrial, medical, and agricultural innovations.
Genomics:
- The study of entire genomes, focusing on gene sequencing and functional analysis.
Conservation Biology:
- Aims to protect biodiversity and vital ecosystems.

Charles Darwin:
- Proposed evolution theory via natural selection.
Gregor Mendel:
- Known as the father of modern genetics for his work on inheritance in pea plants.
James Watson and Francis Crick:
- Discovered the structure of DNA, contributing significantly to genetics.