Characteristics of Life
9/24
Title, date in notebook – required notes
Paraphrase what is here – your own words!
Available on my website (as are most
PowerPoints/presentations)
Disclaimer!
• These ideas can be organized in different ways
• 8 characteristics (according to your textbook)
• Could combine 2 characteristics to get a list of 7
• Could expand a few to get a list of 10…
• Some characteristics are clear/straightforward; others are a bit “messy”
• Some organisms don’t neatly meet the characteristics!
All living things…
• Write the words, “All Living Things:”
• Record each characteristic and brief notes.
• Paraphrase what we discuss!
Made up of cell(s)
• What is a cell?
• Collection of living matter surrounded by a barrier
• Barrier separates it from its surroundings
• Living organisms are either:
• Unicellular
• One cell (bacteria, some algae)
• Multicellular
• More than one cell (most species)
• All cells contain water
• Complex organisms can have hundreds of types of cells!
Reproduce
(without completely relying on other organisms)
• What is reproduction?
• Creation of new organism(s) that meet all characteristics of life
• Species must be capable of reproduction
• Types of reproduction?
• Asexual –
• One cell/organism “splits”, forms cells that are (mostly) genetically identical
• Sexual –
• Two cells from two parents come together to make a new organism
• Viruses not alive (?)
• Need host organisms to reproduce (this can be a gray area)
Are based on a genetic code
• All living things contain either DNA or RNA (or both)
• DNA/RNA contains the instructions necessary for life processes
• Instructions for proteins
Take in materials/energy,
Produce waste
• Examples?
• Take in: oxygen, sunlight, food, water,
• Produce: Carbon dioxide, methane, oxygen, water
• Living things do not all need oxygen!
• Some are anaerobic – no oxygen
Grow and develop
• At some point in their lives, organisms:
• Grow larger, develop new features
• Not all living things have differentiated tissue (e.g., brain, hearts, lungs)
• Complex organisms experience differentiation  new types of tissues
• Simple organisms  no differentiation (cells/tissues all same)
Respond to their environment
• All living things respond to some (few or many) stimuli in their environment
• Examples?
• Respond to smells, sights, sounds, physical stimuli, environmental conditions
• Totally unresponsive to all stimuli = not living
Maintain an internal balance
• Homeostasis?
• Responding to your environment to keep your internal balance in some stable
range over time.
• Examples?
• 1) exercise, red face to let heat out; cold, shiver to warm up;
• 2) low light, pupils dilate to allow same amount of light in;
• 3) splashing water on face, heart rate lowers
• All living things maintain SOME time of internal balance
• If an object’s internal conditions are always the same as its external environment, not alive!
As a species, evolve over time
• Evidence supports – all living species have changed over time
• Some slowly, some quickly
• Every species evolves over long periods of time
• Evolve: DNA of a species change over time – new characteristics develop
So, were the 7 items alive?
• On the board…we’ll split into 4 categories (based on feedback yesterday)
• Alive
• Show all 8 characteristics
• Nonliving
• Never showed all 8 characteristics
• Dormant
• Has the potential to show all 8 characteristics
• Dead
• One showed, but no longer show, all 8 characteristics