Studying Life: What does it mean to be alive?

Objectives: 1. Describe some

characteristics of living things

2. Explain how life can be studied at different levels

Question:1. What does it mean to be

alive?2. What do all living things

have in common?3. Are there any non-living

objects that have living characteristics? Is this fire alive???

1. Cells All living things are made

up of cells Cells are the smallest units

of an organism that can be considered alive

Cells can grow, respond, and reproduce

Despite their small size, they are complex and highly organized

Unicellular organisms = 1 cell

Multicellular = many cells

Stem Cells

2. Reproduction All living things produce

other living things There are 2 types of

reproduction

=Sexual: cells from 2 different parents unite to form first cell

=Asexual: New organism as a single parent

3. Based on a Genetic Code

Offspring resemble their parents

Asexual reproduction results in offspring with identical traits

Sexual reproduction creates variety with similar features

DNA: carries directions for inheritance

4. Growth and Development

All living things grow at some point in their lives

For many single-celled organisms growth is simply an increase in size

For multi-cellular organisms they develop from one cell into many through cell division

As the cells develop they take on different rolls

Nerve Cell Skin Cells

Blood Cells

5. Materials and Energy Organisms need materials

and energy to stay alive Metabolism: process of

breaking down materials for energy that is needed to make other vital materials

Autotrophs: use sunlight as their source of energy

Heterotrophs: consume other organisms for energy

Autotroph or Heterotroph?

6. Response to Environment Organisms detect and

respond to stimuli in the environment

7. Maintain Internal Balance Homeostasis: process of

maintaining a stable internal environment (Temperature)

8. Evolution Change of a species over

time

Individuals do not evolve Groups of organisms can

change