Transcript Parts of a Cell

Grade 8 Science
Chapter 1
Observing Cells
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Chapter 1.3
Cells
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Organelles – Parts of a Cell
• Each
cell must carry out certain
activities that keep it alive.
• To carry out these functions,
cells must have some basic
structures.
• These structures inside the cell
are known as organelles.
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Plant Cell
Plant Cell
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Animal Cell
Animal Cell
Plant Cell vs Animal Cell
How do the two cells differ?
How are the two cells the same?
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Parts of a Cell
• Most
organelles appear in both
plant and animal cells.
• Two specific organelles appear
only in plant cells (cell wall &
chloroplasts)
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Parts of a Cell
Membrane –
• like a skin around the cell
• surrounds and protects the cell
• controls the movement of
substances into and out of the
cell.
• Cell
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Parts of a Cell
–
• jelly-like, constantly in motion
• takes up most of the space in a
cell; supports the structure
• distributes materials around the
cell
• Cytoplasm
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Parts of a Cell
–
• controls the cells activities
• contains the chromosomes
• enclosed by a nuclear
membrane that controls what
enters and leaves nucleus
• Nucleus
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Parts of a Cell
–
• balloon-like spaces
• storage spaces for food, wastes
and other substances
• surrounded by a membrane
• Vacuoles
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Parts of a Cell
Reticulum –
• folded membrane
• forms system of canals within
cytoplasm
• materials are transported in
canals to different parts of the
cell
• Endoplasmic
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Parts of a Cell
–
• Energy production for the cell
• Tiny food particles broken down
for energy
• “Powerhouse” of the cell
• Mitochondria
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Parts of a Cell
Wall –
• only in plants and fungi
• thick and more rigid than
membranes; cellulose
• provide strength and support
for cell
• Cell
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Parts of a Cell
• Chloroplasts –
• only in green plants and some
unicellular organisms
• where photosynthesis happens
• green pigment called
chlorophyll
Why…
• Why are cells sooooooo small?
Imagine…
• You are in a swimming
pool…
• If the pool gets
bigger, what happens
if you are trying to
swim across it several
times?
Is bigger better?…
Investigation 1 – F
Page 32-33
Volume of Cube = s3
Surface Area of Cube = 6s2
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Cell Size and Function
• Why are cells so small?
• The ONLY way in or out is through
the cell membrane.
•To carry out their work, calls need a
constant supply of materials such as
oxygen, water and food and get rid of
waste.
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Small, Smaller, Smallest
•Most cells fall into a narrow range
of size
• To grow bigger, organisms add
more cells to their bodies rather
than grow bigger cells
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Small, Smaller, Smallest