Transcript File ch2 sect1 characteristics of living things (organisms1

Ch2 Sect1 Characteristics of
Living Things (Organisms)
1. Cellular Organization - all organisms are
made of cells
2. Chemicals of Life
3. Energy Use - cells use energy to
perform jobs, such as repair parts and
move chemicals around
4. Response to Surroundings
5. Growth and Development
6. Reproduction - Producing offspring that
are similar to the parents
1. Cellular Organization - all
organisms are made of cells
• A. Unicellular - an organism made up of
only 1 cell
• B. Multicellular - an organism made up
of many specialized cells that do certain
tasks
2. The chemicals of life
• All living things are composed of four basic
elements:
• Carbon (C)
• Hydrogen (H)
• Nitrogen (N)
• Oxygen (O)
• Other important elements include Iron (Fe), Calcium
(Ca), Phosphorous (P), and Sulfur (S).
• Together, these elements make up the main
compounds of life: carbohydrates, proteins,
lipids and nucleic acids.
2. Chemicals of Life
• A. All cells contain water
• B. Carbohydrates - cells' main energy
source
• C. Protein - cells' building material
• D. Lipids (fats and oils) - energy storage
and building material
• E. Nucleic Acids - genetic material that
direct cellular activities – DNA, RNA
3. Energy Use (metabolism)
- Cells use energy to perform
jobs, such as repair parts, move
chemicals around and make
proteins.
4. Response to Surroundings
• A. Stimulus - a change in an organism's
environment
• B. Response - an action or change in
behavior caused by a stimulus
5. Growth and Development
• A. Growth - become larger
• B. Development - process of change to
become more complex
6. Reproduction - Producing
offspring that are similar to the
parents
• Asexual - one parent and offspring is
identical to that parent.
• Sexual – Usually 2 parents and offspring is
a genetic combination of yet different from
both parents.
What gives the property of life?
• Life is more than adding up the
elements.
• These elements interact with each other
to cause chemical reactions that are
characteristic of life.
Life comes from life
• Living things arise from living things
through reproduction.
• The old, mistaken idea, spontaneous
generation, was that living things could
arise from non-living things = FALSE!
Spontaneous Generation Theory
• Untill 1600s, most people believed that
life came from nonliving matter.
• 1668 – Francesco Redi – Italian doctor
and poet who helped disproved this
theory. (p. 36)
• One of the first scientists to run a
controlled study. Independent variable?
• Whether or not the jar was covered.
Francesco Redi’s Conclusion:
• He demonstrated that the presence of
maggots in decaying meat does not
result from spontaneous generation but
from eggs laid on the meat by flies.
THEREFORE….
• Rotting meat does not produce flies!
Louis Pasteur further disproves
spontaneous generation.
• Pasteur, in the 1800s, conducted more
controlled experiments. (p.37)
• He added broth to two flasks, but only
sterilized one of them by boiling it. He
added curved necks to the flasks so air
could get in, but not bacteria.
• The one not boiled grew cloudy.
• He then broke the neck off the boiled
broth and it finally turned cloudy too.
Pasteur’s conclusion:
• New bacteria arise only from existing
bacteria.
• The experiment of Redi and Pasteur
helped to convince people that living
things do not arise from nonliving
things.
The Needs of Living Things
Water
• Most organisms can live only for a few
days without water.
• Needed for chemical reactions and…
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Obtaining chemicals from surroundings
Breaking down food
Growing
Moving substances around
Reproduction
The Needs of Living Things
Food
• Provides the source of energy to live
• Autotrophs – make their own food ex.
plant using sun’s energy.
• Heterotrophs – obtain food by feeding
on others. (A heterotroph’s energy
source is also the sun, but indirectly,
how?)
The Needs of Living Things
Living Space
• All organisms need a space in which to
live that provides shelter, food and
water.
• Space on Earth is limited, so organisms
often must compete for space.
• How does a tree do this?
The Needs of Living Things
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Stable Internal Conditions
Organisms must keep internal
conditions stable.
Homeostasis - maintenance of stable
internal conditions. Keeps things just
right for cells to function.
Why do you get thirsty?
How do barnacles keep water in their
cells at low tide?