The document outlines the organization of life from cells to organisms, highlighting that all living things are composed of at least one cell. It describes the roles of tissues, organs, and organ systems, emphasizing the interdependence of these structures in maintaining life. Additionally, it introduces the historical context of cell discovery and the differences between prokaryotic and eukaryotic cells, along with their essential components.

1. Cells:
The Basic Units of Life

2. Cells
Tissues
Organs
Organ
Systems
Organisms
O
R
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N
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F
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3. Cells
 Every living thing has at least one cell.
 Some have only one and some have trillions.
 Most cells are too tiny to be seen without a
microscope.
 A chicken egg is one of the largest cells.
 Not all cells look or act the same.
 You have 200 different kinds of cells: blood cells,
bone cells, muscle cells …………

4. Tissues
 A tissue is a group of cells working together to
perform a specific job in the body. The material
around and between the cells is also part of the
tissue.
 Examples of tissue: red blood cells, fat, and muscle

5. Organs
 When two or more tissues work together to
perform a specific job, the group of tissues is
called an organ.
 Examples of organs: stomach, heart, intestines, liver,
lung, and skin
• Plants also have different kinds of tissues that work
together. A leaf is a plant organ that contains tissue that
traps light energy to make food.
Examples of plant organs: stem and roots

7. The Skin
 The skin is the body’s largest organ.
An average-sized person’s skin has a
mass of about 4.5 kg (almost 10
pounds!).

8. Brain Food
 The part of the skin, hair, and nails
that we can see is DEAD tissue. Isn’t
it strange that we put so much
effort into making sure our dead
cells look nice?

9. Organ Systems
 Organs work together in groups to perform
particular jobs. These groups are called organ
systems.
 Each system has a specific job to do in the
body.
 Examples:
 digestive system breaks down food to use by your
body’s cells
 nervous system transmits information back in forth
between the brain and other parts of the body

10. There are 11 main organ systems.
 The organs in the organ system depend on each
other. If any part of the system fails, the whole
system is affected. And failure of one organ
system can affect other organ systems.
 Main organ systems : integumentary system,
skeletal system, muscular system, nervous
system, endocrine system, cardiovascular
system, lymphatic system, respiratory system,
digestive system, urinary system, reproductive
system

11. Organism: Independent Living
 Anything that can live on its own is
called an organism.
 All organisms are made up of at least
one cell.
 organisms made up of one cell –
unicellular
 organisms made up of groups of cells –
multicellular

12. The Big Picture
 Although unicellular and multicellular organisms can
live on their own, they usually do not live alone.
Organisms interact with each other on many different
ways.
 Populations – groups of organisms that are of the same kind
and that live in the same area
 Example – all the white tail deer in the forest
 Communities - two or more different populations living in
the same area
 All the populations combined in the forest (deer, rabbits, snakes,
etc..)
 Ecosystems – all the communities and all the nonliving things
that affect it, such as water, soil, rocks, temperature, and
light
 Ecosystems on land – terrestrial ecosystems
 Ecosystems in water – aquatic ecosystems

14. Discovery of Cells

15. Seeing the first cells
 1665 - Robert Hooke – British scientist –
used cork (soft plant tissue found in the
bark of a tree) – He saw tiny boxes and
called them cells.

16. Early discoveries
 1673 – Anton van Leeuwenhoek – Dutch merchant
– used a handmade microscope to look at pond
scum – He saw many small creatures. He also
looked at blood from animals and teeth
scrapings. First to see bacteria and discovered
that yeast is a unicellular organism.

17. The Cell Theory
Matthias Schleiden – 1838 – all plant parts are made of cells
Theodore Swann – 1839 - wrote the first part of the cell
theory.
o All organisms are composed of one or more cells.
o The cell is the basic unit of life in all living things.
1858 – Rudolf Virchow – wrote the third part of the cell theory
o All cells come from existing cells

18.  All cells have:
 Cell membrane- surrounds all cells; acts as a barrier
between the inside of the cell and its environment;
controls what comes in and what goes out
 Hereditary material – cells receive a copy of hereditary
material (DNA) It controls all of the activities of the
cell and contains the information needed for that
cell to make new cells
 Organelles – structures within a cell that allow it to live,
grow, and reproduce
 Cytoplasm – fluid that surrounds the organelles within a
cell
 Small size – almost all cells are too small to see with the
naked eye

19. Amoebas
 An amoeba is a single celled (unicellular) organism. It cannot get large
enough to be seen. As a cell gets larger, it needs more food and produces
more waste. Therefore more material must be able to move in and out
through the cell membrane.
 To keep up with these demands, a growing cell needs a larger surface area
through which to exchange materials. As the cell’s volume increases, its
outer surface grows too.

20. Benefits of being
Multicellular
 A single cell as big as you would have an incredibly small
surface-to-volume ratio and would not survive because
its outer surface would be too small to allow in the
materials needed.
 Multicellular organisms grow by producing MORE cells,
not LARGER cells.
 An elephant has more cells than you, not larger cells.

21. Many kinds of cells
 Having many different cells that are specialized for
specific jobs allows multicellular organisms to
perform more functions than unicellular organisms.
 Different kinds of cells can form tissues and organs with
different functions.
 Some specialized cells: muscle cells, eye cells, brain
cells….
 Be glad you are not UNICELLULAR! How boring!

22. Two types of cells
Prokaryotic Cells
 Also called bacteria
 World’s smallest cells
 No nucleus
 Circular DNA (shaped like a
rubber band)
 No membrane-covered organelles
Eukaryotic Cells
 More complex
 All other cells
 Have a nucleus
 Have membrane-covered
organelles
 Linear DNA stored in the nucleus

23. Eukaryotic Cells
Animal Cells
1. Nucleus
2. Ribosomes
3. Cell Membrane
4. Endoplasmic
Reticulum
5. Lysosomes
6. Mitochondria
7. Golgi Complex
Plant Cells
1. Nucleus
2. Ribosomes
3. Cell Membrane
4. Endoplasmic Reticulum
5. Lysosomes
6. Mitochondria
7. Golgi Complex
8. Cell Wall
9. Large Vacuole
10. Chloroplast

24. The Cell's Command Center -- The
Nucleus
 Largest and most visible organelle in a eukaryotic cell
 Surrounded by a nuclear membrane for protection
 Stores DNA that has information on how to make all the
cell’s proteins (almost all chemical reactions important to
the cell’s life involve protein)

26. The Energy Plant -- Mitochondria
 ATP (molecule that supplies energy to fuel the
cell’s activities) made here from food molecules
 Bean shaped – surrounded by two membranes
 Must have oxygen
 Highly active cells (such as heart and liver) have
thousand
 Powerhouse of the cell

27. Protein Factory -- Ribosomes
 Make protein chains out of amino acids
 Smallest but MOST abundant organelle
 Not covered with a membrane
 ALL cells have ribosomes (prokaryotes included)

28. The Cell’s Delivery System –
Endoplasmic Reticulum
 Membrane-covered compartment that makes lipids and
other materials for use inside and outside the cell
 Breaks down drugs and other damaging chemicals
 Internal delivery system
 Looks like flattened sacks stacked side by side

29. Shipping– Golgi Complex
Packaging -Vesicles
 Looks like the ER but is located closer to
the cell membrane
 Modifies lipids and proteins from the ER
and delivers them to other parts of the
cell or outside the cell
 Vesicles are pieces of the Golgi complex
that pinches off and stores the final
products

30. Trash Collector -- Lysosomes
 Specialized vesicles in animal cells
 Contain enzymes
 Destroy worn-out or damaged organelles
 Get rid of waste materials and protect the
cell from foreign invaders
 If the membrane of a lysosome opens, the
enzymes will spill out into the cell and kill the
cell. (How a tadpole loses its tail)

31. Plant Cells -- Chloroplasts
 Only found in plants and algae
 Energy-converter
 Has two membranes and structures like stacked
coins and contains chlorophyll – which makes the
chloroplast green
 Chlorophyll traps the energy from sunlight and
uses it to make sugar in the process
photosynthesis.
 Mitochondria then use the sugar to make ATP.

32. Cell Wall
 Found in plant cells
 Outside the cell membrane
 Made of cellulose (sugar)
 Provides strength and support to cell
membrane

33. Water cooler- Vacuoles
 Most plant cells have very large
vacuoles.
 Membrane-covered
 Stores water and other liquids
 When full, helps support the cell
 When empty, the cell shrivels (causing
the plant to wilt)

34. Homeostasis
 (1) The tendency of an organism or a cell to regulate its
internal conditions, so as to stabilize health and functioning,
regardless of the outside changing conditions
 (2) The ability of the body or a cell to seek and maintain a
condition of equilibrium or stability within its internal
environment when dealing with external changes
 In humans, homeostasis happens when the body regulates
body temperature in an effort to maintain an internal
temperature around 98.6 degrees Fahrenheit. For example,
we sweat to cool off during the hot summer days, and we
shiver to produce heat during the cold winter season.

35. Connective Tissue
 Joins, supports,
cushions and
insulates
 Examples: blood,
bone, cartilage,
ligaments,
tendons,

36. Epithelial Tissue
 Epithelial tissues
consist of continuous
sheets of cells that
provide a protective
covering over the
whole body
 They also form the
lining membranes of
internal organs,
cavities, and
passageways and
cover internal organs

37. Muscle Tissue
Contracts or
shortens to
cause
movement

38. Nerve Tissue
 Carries message
to and from the
brain
 Allows us to
see, hear,
feel…….
 Makes up brain,
spinal cord and
nerves