BACTERIA & PROTISTS
HAVE CHARACTERISTICS
OF LIVING THINGS, WHILE
VIRUSES ARE NOT ALIVE
SINGLE –CELLED ORGANISMS
AND VIRUSES
SINGLE-CELLED
ORGANISMS & VIRUSES
• SINGLE-CELLED ORGANISMS HAVE ALL
THE CHARACTERISTICS OF LIVING
THINGS
• BACTERIA ARE SINGLE-CELLED
ORGANISMS WITHOUT NUCLEI
• VIRUSES ARE NOT ALIVE BUT AFFECT
LIVING THINGS
• PROTISTS ARE A DIVERSE GROUP OF
ORGANISMS
SINGLE-CELLED ORGANISM
• Living things come in
many shapes & sizes
• Living things share
common
characteristics
• Living things need
energy, materials, &
living space
• Viruses are not alive
Living things come in many
shapes & sizes
• One of the largest living organisms is the honey
mushroom fungus living mostly underground
(about 3 miles or over 1600 football fields)
• Any living thing is called an organism
• Microorganisms are very small organisms, and
made of just one cell. (need microscope to see)
• Scientists divide the organisms they identify into
groups called KINGDOMS.
Common Characteristics
• ORGANIZATION: cells are the basic unit of all
living things. Cells are able to get energy from
and sense their environment and move.
• GROWTH: living things increase in size. All
living things need energy & materials to build or
repair its structures.
• REPRODUCTION: reproduce to form other
organisms like themselves. Binary fission =
material from 1 cell, splits in 2. Some single
celled organisms use this to reproduce.
• RESPONSE: respond to changes in environment
(light, temperature, touch, etc. lets them find food
or do other tasks needed for survival).
NEEDS
• Living things need ENERGY, MATERIALS &
LIVING SPACE
• FOOD: supplies you with energy (to move, grow
& develop). Animals break down food to usable
forms, plants transform sunlight to usable energy.
• WATER: most activities of living things take
place in water (all of cell’s reactions)
• AIR: CO2 & O2 (oxygen) are some things in air
that most organisms use to capture & release
energy through. Some organism (in
hydrothermal vents) use other chemicals to
capture & release energy.
VIRUSES ARE NOT ALIVE
• VIRUS has genetic material enclosed in a protein
shell.
• Viruses have many of the characteristics of living
things but not as complex as a cell and not
considered a living thing.
• Animal cells have structures that let them get
materials or energy from environment, while
viruses do not. They do not grow once formed.
• Viruses can’t reproduce on own, but must “take
over” a cell to use it to make more viruses.