Download What is Diffusion or Passive Transport?

Figure 8.6 The detailed structure of an animal cell’s plasma
membrane, in cross section
Cellular Transport
Chapter 8
Figure 8.4 The fluidity of membranes
Cells move substances
through the cell membrane by
a process called transport
• Two Types of Transport:
–Passive Transport
–Active Transport
Figure 8.9 Some functions of membrane proteins
What is Diffusion or
Passive Transport?
• Requires no energy from cell.
• Molecules move from
high concentration to
low concentration.
• Molecules move with the
concentration gradient.
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Figure 8.10 The diffusion of solutes across membranes
Osmosis is a type of
diffusion
How would diffusion
happen in a cell?
Figure 8.11 Osmosis
Cell Membrane
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Facilitated Diffusion
Figure 8.14 Two models for facilitated diffusion
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can help!
tranport proteins help substances
(glucose) pass through the cell
membrane. Still passive transport
no energy required.
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Water balance of cells
without walls:
80% H2O
80% H2O
Which way did the
water move?
80% H2O
80% H2O
100% Distilled
Water
80% Water
20% Dissolved
Substances
70% Water
30% Dissolved
Substances
Which way did the
water move?
80% H2O
80% Water
20% Dissolved
Substances
100% Distilled
Water
Why did the cell
get so big?
Which way did the
water move?
80% H2O
Why did the cell
stay the same
size?
Figure 8.12 The water balance of living cells
70% Water
30% Dissolved
Substances
Why did the cell get
so small?
Figure 8.13 The contractile vacuole of Paramecium: an
evolutionary adaptation for osmoregulation
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Figure 8.15 The sodium-potassium pump: a specific case
of active transport
Figure 8.18 Cotransport
Figure 8.17 An electrogenic pump
How is Active
Transport different?
1. Active transport requires energy.
2. Molecules move from low
concentration to high
concentration
3. Molecules move against
concentration gradient.
Figure 8.16 Review: passive and active transport
compared
Endocytosis
• Cells bring large in particles using
cell membrane
– There are 2 types:
• Phagocytosis
• Pinocytosis
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Pinocytosis
Phagocytosis
Amoeba
• This is the ingestion of large particles.
• Your white bloods cells also do this.
• Tiny pockets form along cell membrane, and
pinch off into vacuoles inside the cell.
Sometimes called “Cell Drinking”
Figure 8.19 The three types of endocytosis in animal cells
Exocytosis
• This is how the cell gets rid of waste.
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