Cells: The Basic Units of Life

1
Chapter 3

• Cells The Basic Units of Life

2
Section 1 Objectives

• State the parts of the Cell Theory.
• Explain why cells are so small.
• Describe the parts of a cell.
• Describe how Eubacteria are different from
  Archaebacteria.
• Explain the difference between prokaryotic cells
  and eukaryotic cells.

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The Diversity of Cells

• All living things are made up of cells.
• Cell smallest unit that can perform all life
  processes
• Because of their size, cells werent discovered
  until the mid-1600s.

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The Diversity of Cells

• Robert Hooke was the first person to discover
  cells.
• He examined cork (from the bark of trees).
• The cork looked like it was made of little boxes
  (cells).

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The Diversity of Cells

• In 1863, Anton van Leeuwenhoek made his own
  microscopes.
• He examined organisms in pond water.
• Animalcules little animals

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The Diversity of Cells

• Today we call these protists.
• He also examined animal blood.
• Leeuwenhook was the first person to examine
  bacteria.

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The Diversity of Cells

• Almost 200 years passed before scientists
  concluded that cells are present in living
  things.
• As years passed many more scientists contributed
  to the examination of cells.
• 2 of these scientists were Schleiden and Schwann.
• Schleiden studied plants and Schwann studied
  animals.
• They concluded that plants and animals were made
  of cells.

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The Diversity of Cells

• Schwann wrote the first 2 parts
• All organisms are made up of one or more cells
• The cell is the basic unit of all living things
• Virchow wrote the third part
• All cells come from existing cells

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The Diversity of Cells

• All cells are surrounded by a cell membrane.
• Cell membrane protective layer that covers the
  cells surface and acts as a barrier (separates
  cell from environment)
• The cytoplasm is the fluid inside the cell and
  all of its contents.

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The Diversity of Cells

• Organelles are structures that perform specific
  functions within the cell
• Different types of cells have different
  organelles.
• Most organelles are surrounded by membranes.

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The Diversity of Cells

• All cells contain DNA.
• DNA is the genetic material that carries
  information needed to make new cells and new
  organisms.

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The Diversity of Cells

• In most cells, the DNA is located in the nucleus.
• Bacterial cells do not have a nucleus.
• Does this mean bacterial cells do not have DNA?

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The Diversity of Cells

• There are 2 kinds of cells
• Prokaryotic single cell with no nucleus
• Eukaryotic more than one cell with a nucleus

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The Diversity of Cells

• Prokaryotes Single-celled organisms with no
  nucleus or membrane-bound organelles
• Example Bacteria
• Prokaryotes include
• Eubacteria
• Archaebacteria

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The Diversity of Cells

• Eubacteria
• Most common prokaryotes (bacteria)
• Bacteria are the worlds smallest cells.
• Do not have a nucleus, but do have DNA (long,
  circular molecule)
• Have no membrane-bound organelles.
• Do have ribosomes (round organelles made of
  protein)

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The Diversity of Cells

• Eubacteria
• Bacteria have a strong, web-like exterior cell
  wall.
• Has a cell wall and a cell membrane.
• Bacteria live in
• Soil
• Water
• In/on organisms

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The Diversity of Cells

• Archaebacteria
• Ancient bacteria
• Not as common as Eubacteria but similar.
• Has DNA, cell wall, cell membrane, and ribosomes.
• Its ribosomes are different than the ribosomes of
  Eubacteria.

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The Diversity of Cells

• Archaebacteria
• There are 3 types
• Thermophiles heat-loving
• Halophiles salt-loving
• Methanogens Methane-makers
• Extremophiles live in places where conditions
  are extreme

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The Diversity of Cells

• Eukaryotes
• The largest cells (10 X larger than bacterial
  cells)
• Have a nucleus and membrane-bound organelles.
• Nucleus contains DNA.
• Multicellular (more than 1 cell)
• Examples Humans, animals, plants

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Section 2 Eukaryotic Cell Organelles

• Objectives
• Identify the different parts of a eukaryotic cell
• Explain the function of each part of a eukaryotic
  cell

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Eukaryotic Cell Organelles

• 1. Cell wall rigid structure that gives support
  to a cell
• Plants and algae have a cell wall made of
  cellulose complex sugar
• Fungi also have cell walls made of chitin
  chemical in fungi

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Eukaryotic Cell Organelles

• 2. Cell Membrane
• All cells have a cell membrane.
• Protective barrier that encloses the cell
• Outermost structure for cells with no cell wall.
• Contains lipids (fats), proteins, and
  phospholipids.
• What is the unique quality of lipids?

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Eukaryotic Cell Organelles

• 3. Cytoskeleton
• Web of proteins in the cytoplasm.
• Acts as a muscle and a skeleton.
• Keeps cell membrane from collapsing.
• Also helps cells move.
• Backbone of the cell

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Eukaryotic Cell Organelles

• 4. Nucleus
• Large organelle that contains DNA.
• DNA contains information for how to make
  proteins.
• Proteins control the chemical reactions in a cell
  and provide structural support.

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Eukaryotic Cell Organelles

• 5. Nucleolus dark area inside the nucleus where
  ribosomes are made
• The nucleus also has a double membrane.

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Eukaryotic Cell Organelles

• 6. Ribosomes
• Organelles that make proteins
• Smallest of the organelles.
• Most abundant organelle.
• Not covered by a membrane.

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Eukaryotic Cell Organelles

• 7.Endoplasmic Reticulum (ER)
• Site of many chemical reactions.
• System of folded membranes.
• Produces proteins and lipids.
• Part of the internal delivery system of the cell.
• Substances move through the ER to different parts
  of a cell.

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Chapter 3 Review Questions

• What is an extremophile?
• Where is DNA located in most cell?
• What is a prokaryote?
• What is a eukaryote?
• ____ ____ is a protective membrane that encloses
  a cell.
• What do ribosomes produce?

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Eukaryotic Cell Organelles

• 7.Endoplasmic Reticulum
• There are 2 types
• A) Smooth ER ER that lacks ribosomes
• Makes lipids
• Breaks down materials that could harm the cell
• B) Rough ER contains ribosomes
• Found near the nucleus
• Makes proteins

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Eukaryotic Cell Organelles

• 8. Mitochondria
• Main power source of the cell.
• Have their own DNA.
• Breaks sugar down to produce energy.
• Energy released by mitochondria is turned into
  ATP.
• Most of a cells ATP is produced in the
  mitochondria.

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Eukaryotic Cell Organelles

• 9. Chloroplasts
• Organelles in plants/algae where photosynthesis
  takes place.
• They are green because they contains chlorophyll,
  a green pigment.
• This absorbs sunlight and uses it to make sugar.
• What is the sugar used for in the cell?

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Eukaryotic Cell Organelles

• 10. Golgi Complex
• Packages and distributes proteins.
• Looks like smooth ER.
• Lipids and proteins from the ER are sent to the
  Golgi Complex.
• After being modified, they are enclosed in a
  membrane which pinches off to form a small bubble
  and then transported to other parts of the cell
  or out of the cell.

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Eukaryotic Cell Organelles

• 11. Cell Compartments
• The bubble that forms the Golgi complexs
  membrane is a vesicle (small sac that surrounds
  material to be moved into or out of the cell)
• Vesicles also move materials around the cell.

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Eukaryotic Cell Organelles

• 12. Lysosomes
• Responsible for cellular digestion.
• Have the following functions
• Destroy damaged organelles
• Gets rid of waste materials
• Protects cell from foreign invaders

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Eukaryotic Cell Organelles

• 13. Vacuoles
• Large vesicle
• In plant and fungal cells, some act like large
  lysosomes.
• Some store digestive enzymes while others store
  water.
• What happens to a plant when its vacuoles lose
  water?

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Chapter 3 Review Questions

• What is the difference between smooth and rough
  ER?
• What does the mitochondria do for the cell?
• What cells are chloroplasts located in and what
  takes place there?
• The Golgi complex ____ and _____ proteins.
• List 3 functions of lysosomes.

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Cell Organelle Review

• 1) Cell membrane
• 2) Nucleus
• 3) Chloroplast
• 4) Ribosomes
• 5) Endoplasmic Reticulum
• 6) Golgi complex
• 7) Mitochondria

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Section 3 Objectives

• List the three advantages of being
  multi-cellular.
• Describe the four levels of organization in
  living things.
• Explain the relationship between the structure
  and function of a part of an organism.

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Organization of Living Things

• In some ways, organisms are like machines.
• Some machines have just one part but most
  machines have many parts that work together to
  achieve a common goal.
• The same concept is true for organisms and cells.

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Organization of Living Things

• Most cells are smaller than the period at the end
  of this sentence.
• Every cell in an organism performs all life
  processes.
• Are there advantages to having more than one cell?

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Organization of Living Things

• Mutli-cellular organisms contain many cells.
• What kinds of organisms are multi-cellular?
• There are 3 benefits to being multicellular
• Larger size
• Longer life
• Specialization

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Organization of Living Things

• Multicellular organisms are usually larger than
  unicellular organisms.
• Larger organisms are prey for fewer organisms.
• Larger predators can eat a wider variety of prey.
• What are some large predators?
• What are some predators that are restricted by
  their size?

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Organization of Living Things

• The life span of a multicellular organism is
  longer than that of a unicellular organism.
• Why is this generally
• true?

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Organization of Living Things

• Multi-cellular organisms are specialized.
• This (specialization) means that each type of
  cell has a particular job.
• Specialization makes organisms more efficient.
• Heart muscles are an example. They contract and
  help the heart pump blood.

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Organization of Living Things

• A tissue is a group of cells that work together
  to perform/complete a specific task.
• Plants and animals have different types of
  tissues.
• Why would plants and animals have different types
  of tissues?
• Hint Do they have different types of cells?

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Organization of Living Things

• A structure made up of 2 or more tissues working
  together is an organ.
• An example of an organ would be the heart or the
  brain.
• What are some other examples of organs?

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Organization of Living Things

• A group of organs working together to perform a
  particular function is called an organ system.
• The digestive system is an example.

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Organization of Living Things

• Anything that can perform life processes by
  itself is an organism.
• Some organisms live in colonies where they depend
  on each other to survive.
• Bacteria

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Organization of Living Things

• In organisms, structure and function are related.
• Structure is the arrangement of parts in an
  organism
• Function is the job each part does

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Organization of Living Things

• An example of this would be the respiratory
  system
• The structure of the lungs is a large, spongy
  sac. There are millions of tiny sacs here called
  alveoli. Blood vessels wrap around the alveoli.
  Oxygen from the air enters the blood and blood
  brings oxygen to the tissues.