Cells: The Building Blocks of Life What is Life?

An organism is a living thing.

Six characteristics of all living things are: Cellular organization Contain similar chemicals Use energy Grow and develop Respond to their surroundings Reproduce

Cells are the basic building blocks of all living things. The basic unit of structure and function.

Cellular organization Cells Tissue Organs Organ systems

Unicellular An organism with only one cell.

Multicellular An organism with many cells.

Chemicals of Life Water is the most abundant chemical in cells. Proteins and lipids are the building materials of cells. Nucleic acids are the genetic material that direct the cell’s activities. Carbohydrates provide the cell with energy.

Cells use energy for all life processes. Ex: grow, repair cells, Digest food, respond to stimuli, reproduce

Growth- the process of becoming larger. Development- the process of change that occurs during and organism’s life.

Response to Surroundings Stimulus- A change in an organism’s surroundings that causes an organism to react. Example: light, sound, temperature, chemicals, pressure, etc. Response- An action or change in behavior due to a stimulus. Example: blinking, shivering, sweating, jumping, crying, pupils changing shape, etc.

Reproduction Produce offspring that are similar to the parents.

Life Comes From Life Spontaneous Generation-mistaken theory that living things arise from nonliving things.

Experiments to disprove spontaneous generation. Francesco Redi Flies do not spontaneously arise from decaying meat. Louis Pasteur Spontaneous generation does not occur with bacteria.

Redi’s Experiment Manipulated (independent variable) was the covering on the jar.

Pasteur’s Experiment Manipulated (independent variable) was boiling the broth in one flask.

The Needs of Living Things Energy Water Living space Stable internal conditions (homeostasis)

Organisms use food as their source of energy. Autotrophs- (auto means self; troph means feeder ) organisms that make their own food. Heterotrophs- (hetero- means other) organisms that cannot make their own food.

Invention of the microscope made it possible to discover cells. Robert Hooke observed a thin slice of cork and discovered rectangular shaped structures he called cells. Anton van Leeuwenhoek observed pond water and called the small organisms “animalcules”

Scientists responsible for the cell theory. Matthias Schleiden- stated all plants are made of cells. Theodor Schwann- stated all animals are made of cells. Rudolf Virchow- stated all cells come from other cells.

The Cell Theory All living things are composed of cells. Cells are the basic unit of structure and function in living things. All cells are produced from other cells.

Plant cells Onion cell Cork cell Elodea cells

Animal Cells Frog blood cells Blood cells Cheek Cells