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Cells
Biology
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How many cells do we have?

There are approximately 1x1014 cells in the
human body…
1,000,000,000,000,000
 Oh, that’s
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about 100 trillion!
Cell Theory
1)
2)
3)
All living things are composed of one or
more cells.
The cell is the smallest entity that retains the
properties of life.
New cells arise only from cells that already
exist.
Organelles

Organelles = specialized subunit within a cell
that has a specific function, and is usually
separately enclosed

Like organs in our bodies, cells have organelles.
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Animal Cell
Cytoplasm
Ribosomes
Nucleus
Cell Membrane
Mitochondria
Rough
Endoplasmic
Reticulum
Golgi Complex
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Smooth
Endoplasmic
Reticulum
Vacuole
Cell Membrane/ Plasma Membrane
Nickname: “The gatekeeper”
Function:
 separates the inside of the cell from the
external environment
 controls the flow material into and out of the
cell
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Cell Membrane/ Plasma Membrane

The cell membrane allows only some
substances to pass through it.

Therefore, it is called a “semi-permeable”
membrane.
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Cytoplasm

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a thick liquid residing between the cell
membrane holding all organelles
Cytoskeleton
Nickname: “The Skeleton”
Function:
 cellular "scaffolding" or "skeleton" contained within
the cytoplasm and is made out of protein
Gives the cell structure and shape
 Act as rail road tracks for moving things around

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Cytoskeleton
Microtubules
 Actin Filaments

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Nucleus
Nickname: “The Control Center”
or “Brain”
Function:
 Controls all cell activities
 Holds the DNA (genetic material)
 Regulates gene expression
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Mitochondria
Nickname: “The Power House”
Function:
 Produces energy to power cell activities
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Ribosomes
Nickname: “Protein Factory”
Function:
 Make proteins
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Endoplasmic Reticulum (ER)
Nickname: “Roads”
Function:
 Internal delivery system of the cell
 Made up of channels that transport material
made in the cell from one place to another
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2 Types of Endoplasmic Reticulum

Smooth Endoplasmic Reticulum (SER)



Rough Endoplasmic Reticulum (RER)



No ribosomes attached
Makes fats or lipids
Has ribosomes attached
Helps make proteins
Products of the ER become enclosed in
vesicles and travel to the golgi apparatus
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Golgi Apparatus
Nickname: “The Shippers”
Function:
 Sorts products from the
ER and packages them into
vesicles
 packages, modifies, and
transports materials to
different location
inside/outside of the cell
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Vesicles
Nickname: “Delivery Person”
Function:
 small membranous spheres that transport
materials around cell
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Lysosomes
Nickname: “Clean Up Crew”
Function:
 Contain proteins (enzymes) that break down
food into smaller particles that the rest of the
cell can use
 Destroy old cells, recycle the parts
 Destroy invaders
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Lysosomes

Fuses with other vesicles to digest nutrients
brought into the cell or destroy dangerous
microorganisms.
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Centrioles
Nickname: “Spiderman”
Function:
 Protein tubes that play a role in cell division
 Shoot out spindle fibers that guide
chromosomes during cell division
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Plant Cells
Section 7-2
Central Vacuole
Chloroplasts
Cell Membrane
Cell Wall
Go to
Section:
Plant Cells
Cytoplasm
Central Vacuole
Smooth ER
Ribosomes
Chloroplasts
Cell Membrane
Cell Wall
Nucleolus
Golgi Bodies
Nucleus
Mitochondria
Rough ER
Cell Wall
Function:
 provides support and protection to the cell
membrane
Location:
 Outside the cell membrane in plant cells
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Chloroplast (a type of Plastid)
Nickname: “Powerhouse of Plants”
Function:
 Traps energy from the sun to produce food for
the plant cells (photosynthesis)
 Contains chlorophyll = the green pigment
that begins the process of photosynthesis
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Chloroplast
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Chloroplasts Under a Microscope
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Central Vacuole
Function:
 Store water
Vacuoles play a role in turgor pressure
 When a plant is well-watered, water collects in
cell vacuoles producing rigidity in the plant
 Without sufficient water, pressure in the
vacuole is reduced and the plant wilts

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Comparing Plant and Animal Cells
Plant
•
•
•
•
Cell wall
Plastids
Chloroplasts
Central
Vacuole
• Plasma
membrane
• Nucleus
• Mitochondria
• Ribosomes
• Golgi
• Endoplasmic
Reticulum
• Cytoplasm
• Cytoskeleton
• Small vacuoles
Animal
• Centrioles
• Lysosomes