Characteristics of Life9/24

Title, date in notebook – required notesParaphrase 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