Introduction to Biology

scientific study of life. What is Biology? Biology is the scientific study of life.

Earth: Unity of Diversity Scientist believe there are between 5 million and 30 million species on earth. To date: only ~1.5 million species have been identified.

Characteristic of Living Things A. Have a complex organization B. Able to reproduce C. Able to grow and develop D. Can transform energy 1. Autotrophic - ex. Plants (light →chemical and cellular energy) 2. Heterotrophic - ex. Animals (chemical → cellular energy) E. Respond to environmental stimuli F. Adapt to the environment and evolve

Biological Levels of Organization 1. Atoms 2. Molecules/Macromolecules: atoms bond to form molecules. Macromolecules include proteins, carbohydrates, lipids, nucleic acids 3. Organelles: macromolecules form cell organelles, such as mitochondrion, and nucleus.

3. Biological levels continued 4. Cells: the basic structural unit of living things. 5. Tissues: Similar cells with the same structure and function form tissues. 6. Organ: A group of different tissues working together form organs. For example the heart.

3. continued 7. Organ Systems: Organs and tissues form the body systems, i.e circulatory, respiratory and the digestive system. 8. Organisms: species: organisms that can breed together to produce fertile offspring (i.e. the babies can also breed with each other)

3. continued 9. Populations: localized groups of organisms belonging to the same species. 10. Community: populations of species living in the same area. 11. Ecosystem: community interactions 12. Biomes: large scale communities (tundra, prairie, rain forest etc) 13. Biosphere: the sum of all earth’s ecosystems.

The Cellular Basis of Life Cells are the lowest level of structure capable of all activities of life.

The Cell Theory A. Cells are the basic structural unit of life. All living things are made of cells.

The Cell Theory B. Cells are the basic functional unit of life. All life processes occur at the cellular level.

The Cell Theory C. Cells arise from pre-existing cells (through the processes of mitosis, meiosis).

The Cell Theory D. In a multicellular organism, the activity of the organism depends on the total activity of each cell.

The Cellular Basis of Life Two major cell types: 1. Prokaryotic Cells: a. no membrane bound organelles b. no nuclear membrane (DNA is circular) 2. Eukaryotic Cells: a. have membrane bound organelles b. have a nuclear membrane (DNA is linear)