1. An Introduction to Life

2. Objectives:
Explain the basic characteristics shared by all living things.
Identify the levels of organization found in living organisms.
Explain the system of classification used for living organisms.

3. A living thing is called an:
Organism

4. Unity and Diversity of Life
Organisms:
Share characteristics that distinguish them from non living things (Unity of Life)
Show tremendous differences in form and function (Diversity of Life)

5. All Living Things: Are Organized Acquire Materials and Energy
Respond to changes in their environment
Reproduce and Develop
Have Adaptations
Have Nucleic Acids as a way to control activities.

6. All living things: Are made up of one or more cells.
The cell is the smallest unit that can be said to be alive

7. All cells are complex, highly organized, and contain many different types of chemicals or molecules.
These chemicals are made up of smaller units – atoms

8. Unicellular organisms have only one cell.
Multicellular Organisms have more than one cell.

9. In Multicellular Organisms:
Similar cells form tissues
Tissues combine to form organs
Organs work together in organ systems
Organ systems form a complex organism.

10. Levels of Organization:

11. All Living Things: Acquire Materials and Energy
Metabolism is the sum of all the chemical reactions in an organism
During metabolism an organism will build up molecules or break them down
Energy is needed to carry on all life functions

12. All Living Things: Acquire Materials and Energy
Source of most energy on Earth:
The SUN
Plants create nutrients from the sun’s energy during photosynthesis
Other organisms consume plants and animals to get their nutrients.

13. All living things: Maintain an internal balance
Homeostasis – attempt by the organism to maintain its internal conditions as the external environment changes
Temperature, water, acidity and level of nutrients need to be regulated

14. All Living Things Respond to their Environment
External changes: light, temperature, moisture, gravity
Internal changes: sugar levels, salt concentration, carbon dioxide levels, temperature
Includes behavior and instinct

15. All Living Things Reproduce and Develop
Asexual reproduction – One parent
Sexual reproduction – Two parents

16. All Living Things Have Adaptations
Modifications that allow them to survive in their environment

17. All Living Things Have Adaptations
Modified over time by natural selection
Preserves genetic changes
Makes them better suited for their environment.

18. All Living Things Have Adaptations
Evolution is descent with modification, driven by natural selection
One species can be an ancestor to many species
Explains diversity and unity

19. All Living Organisms Have Nucleic Acids to control activities
DNA (deoxyribonucleic acid) or
RNA (ribonucleic acid)
Contain instructions for the cell
Carry hereditary information to next generation

20. Organizing Life
Because living things are diverse, taxonomy was created to group organisms into categories and to understand their evolutionary relationships.
Least inclusive
Most inclusive
Domain Kingdom Phylum Class Order Family Genus Species

21. Organizing Life - Domains
Three domains:
Archaea
Bacteria
Eukarya
Based on Cell Structure and Function
Prokaryotic cells do not have a true nucleus
Eukaryotic cells have a membrane around their nucleus

22. Organizing Life - Domains
Archaea and Bacteria are both comprised of prokaryotic bacteria.
Archaea bacteria live in extreme environments.
Anoxic (no oxygen)
High salinity
High temperature
Bacteria Domain includes most pathogenic bacteria

23. Organizing Life - Domains
Eukarya consists of all non-bacterial organisms.
Eukarya is divided into four kingdoms.
Protista
Fungi
Plantae
Animalia

24. The four kingdoms of Eukarya

25. Organizing Life – Scientific Names
Unique scientific names are used to identify and classify organisms.
The scientific name is called the binomial name and consists of a genus and species.
Peas: Genus = Pisum; species = sativa
Pisum sativa
Humans: Genus = Homo; species = sapiens
Homo sapiens

26. Can you:
Explain the basic characteristics shared by all living things?
Are Organized
Acquire Materials and Energy
Respond to changes in their environment
Reproduce and Develop
Have Adaptations
Have Nucleic Acids as a way to control activities

27. Identify the levels of organization found in living organisms?
Can you:
Identify the levels of organization found in living organisms?
Atoms
Molecules
cells
tissues
organs
organ systems
complex organism

28. Explain the system of classification used for living organisms?
Can you:
Explain the system of classification used for living organisms?
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Largest group
Smallest group