Transcript Cell Transport

Cell Transport
How substances move into and
out of cells
What types of things need to
get in & out of cells?
• Organic compounds lipids, proteins, &
carbohydrates)
• Water
• Cellular waste (CO2, ammonia)
• Solutes/inorganic molecules (salts,
vitamins, minerals)
How do these things get
across the cell membrane?
Cell Membrane
• Composed of a lipid bilayer (two-layered)
embedded with proteins
• The cell membrane is selectively permeable or
semi-permeable: some things can pass freely
through it while others cannot
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Internal & External Cell
Environment
• Every cell is filled with water and solutes
(cytoplasm) and surrounded by water and
solutes
• Solute: Substance that is dissolved in a liquid
• Solutes includes both organic compounds
(fats, proteins, amino acids, starches) and
inorganic compounds (salt, vitamins, minerals)
• Water and solutes cross the cell membrane
Two ways a cell transports
substances across its
membrane
Cell Transport
Passive Transport
Requires no energy from the cell
Active Transport
Requires energy from the cell
Passive Transport
• Movement of substances across membranes
without adding energy
• Substances naturally move from areas of HIGH
to LOW concentration
• Small particles/water go through the lipid bilayer
• Larger particle go through protein channels
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Two types of passive transport
Passive Transport
Diffusion
Movement of molecules/solute
From HIGH to LOW concentration
Requires no energy
Osmosis
Movement of water
From HIGH to LOW concentration
Requires no energy
Tonicity
• Comparison of solute concentration
inside and outside the membrane
• Hypertonic- the area with the higher
concentration of solute
• Hypotonic- the area of lower solute
concentration
• Isotonic- equal concentration of
solutes
Hypertonic Outside
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Hypotonic Outside
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Isotonic
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Equilibrium/Homeostasis
• Occurs when the concentration of a
substance is the same across an
area
• Dynamic Equilibrium: Even though
substances are equal in
concentration on either side of the
membrane, they continue to move
back and forth.
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Active Transport
• When the cell must use energy (ATP) to get
substances across the membrane
• Movement of substances from LOW to HIGH
concentration levels
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• Movement of large
particles
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Three ways cells move large
particles in and out:
Phagocytosis- Extensions of cytoplasm
wrap around and engulf large
particles
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Endocytosis- Cell pinches off
membrane bound packets into cell
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Exocytosis- Cell expels membrane
bound packets out of cell
Finger Mini-Lab
Question: After soaking two fingers in
fresh water and two fingers in salty
water for 15 minutes, how will they look
different?
Hypothesis:
•
•
1. If I soak my fingers in salty water, they will
look _____.
2. If I soak my fingers in fresh water, then they
will look _____.
Conclusion: Were you hypotheses right?
Explain the results, using the following
words:
•
•
Hypertonic, hypotonic, osmosis, diffusion,
solute