2. 1. All living things are made of cells.
2. The cell is the basic structural and
functional unit of life.
3. All cells come from pre-existing cells.
3. Organisms-are individual forms of life that use energy to
carry out activities.
To be classified as living, something must be;
◦ Organized
◦ Grow and develop
◦ Respond to its environment; and
◦ Be able to reproduce.
All organisms need energy, materials, and living space. All
energy used by life on Earth comes from the Sun.
4. The cell is the smallest unit that can perform
the basic activities of life.
Multicellular organisms have specialized cells
that, together, meet the basic needs.
Unicellular organisms are made
up of only one cell.
- ex. Bacteria, some algae plants
5. Robert Hooke and Anton van Leeuwenhoek
first described cells in the 1660s and 1670s.
Microscopes were the new technology that
led to their discoveries of many of the cells
we have today.
6. Three types of microscopes are useful in
studying cells.
◦ Light microscopes can magnify living cells.
◦ Scanning electron microscopes and transmission electron
microscopes can magnify smaller objects, but preparation of
living specimens kills them.
Transmission Electron -
Scanning Electron-
7. In the 1850s people knew for sure that cells
come from other cells.
This fact is part of the cell theory:
1. All living things are made of one or
more cells.
2. Cells carry out the functions needed to
support life.
3. Cells come only from other living
things.
8. A theory is an explanation of what is
observed, and must be supported by
evidence.
Louis Pasteur used the cell theory as a
foundation for his studies.
He found that:
◦ Bacteria causes food spoilage, sour milk, and many
diseases.
◦ Living things do not arise by spontaneous
generations.
9. All cells have cell membranes as a protective
covering.
They all contain cytoplasm, a thick fluid
where most of the work of the cell is done.
Most cells also have genetic material, called
DNA (Deoxyribonucleic Acid).
◦ In prokaryotic cells, DNA is in the cytoplasm.
◦ In eukaryotic cells, DNA is separated from the rest of the cytoplasm in a
nucleus.
10. Eukaryotic cells are much larger than prokaryotic cells. They
have many complex structures, including organelles.
Prokaryotic cells lack a nucleus and other organelles, with DNA
that is not organized into chromosomes.
Organelles called chloroplasts use energy from sunlight to
make sugar.
Cells have mitochondria to make energy available to the
organism.
The endoplasmic reticulum, ribosomes, and Golgi apparatus
process and transport materials.
Other organelles such as vacuoles and lysosomes store and
recycle water and waste.
11.
12.
13.
14. Organisms can be classified by their cell type.
◦ Most organisms on Earth are unicellular. They can
be in one of three domains.
Archaea- are prokaryotes that mostly live in extreme
environments.
Bacteria- are prokaryotes that share some similarities with
archaea, but grow virtually everywhere on Earth.
Eukarya-are eukaryotes, which include multicellular organisms
(plants, animals, fungi and some protists) and unicellular
organisms (some protists).
15. All multicellular
organisms begin life as
a single fertilized egg
cell. As cells divide,
they specialize to
perform specific jobs.
The more
specialization there is,
the more complex the
organism is.
16. Organisms have different degrees of
organization.
For example, sponges have specialized cells, but are not
strictly organized.
◦ Similar cells group together to form tissues.
◦ Tissues act together to form organs.
◦ Organs and tissues act together in organ systems.
17. Scientists use models to make complicated
structures or processes easier to understand.
◦ Some examples of models include mathematical or chemical equations,
diagrams, process models, or physical models.
DNA Model- created by
Watson and Crick
