Homeostasis and Cell Transport

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Bellringer 1
1. The tools that would help you determine
whether one liquid is more dense than another
are A Bunsen burner and scale balance B metric
ruler and graduated cylinder C graduated cylinder
and scale balance D mercury thermometer and
Bunsen burner
2. The unit of measurement you should use to
measure the amount of liquid in a glass is A
grams B kilograms C milliliters D centimeters
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Chapter 5
Homeostasis and Cell Transport
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Objectives

• Distinguish between diffusion and osmosis.
• Distinguish between passive and active transport
• Compare endocytosis and exocytosis

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Cell Memebranes

• The cell membrane regulates what comes in and out
  of the cell
• Semi-permeable some substances can easily pass
  through while others must be helped

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Cell Transport

• Two Types of Transport
• Passive no input of energy
• riding a canoe down stream
• Active requires an input of energy (ATP)
• paddling a canoe against the current

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Passive Transport

• Diffusion movement of molecules from an area of
  higher concentration to an area of lower
  concentration
• Concentration gradient difference in
  concentrations

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Passive Transport

• Diffusion
• Driven by kinetic energy (motion) down the
  concentration gradient
• Eventually will reach equilibrium the
  concentration of molecules will be the same
  throughout (although movement continues)

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Passive Transport

• Diffusion Across Membranes
• Depends on
• Size of molecule
• Shape of molecule
• Type of molecule

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Passive Transport

• Osmosis
• Osmosis is the diffusion of water
• The direction of the movement of water depends on
  the concentration of solutes on the two sides of
  the membrane
• Water will try to equalize the concentration of
  solutes

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Passive Transport

• Types of solutions
• Hypertonic high concentration of solutes
• Hypotonic low concentration of solutes
• Isotonic equal concentration of solutes
• Water tends to diffuse from hypotonic solutions
  to hypertonic solutions

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Passive Transport

• If a cell is placed in a __________solution
• Hypertonic Water will leave the cell (crenation,
  plasmolysis)
• Hypotonic Water will enter the cell (cytolysis)
• Isotonic Equilibrium

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Passive Transport

• Some cells cannot compensate for changes in
  solute concentration
• Crenation cell shrinking (in hypertonic
  solution)
• Cytolysis cell bursting (in hypotonic solution

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Assignment

• Section 1 Review
• p. 102 (1-5) Q A

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Bellringer 2

• Standardized Test
• p. 109 (1-4) Q A

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Facilitated Transport

• Some molecules require help to get across the
  membrane. Facilitate diffusion does not use ATP,
  so it is still passive.
• Facilitate transport used carrier proteins to
  move molecules across the membrane.

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Ion Channels

• Ions are charged particle (Na, Cl-)
• Channels are ion specific
• Some are always open, while some respond to
  stimuli
• Stretching
• Electrical signals
• Chemical signals

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Active Transport

• Cell Membrane Pumps
• Pumps material UP their concentration gradient
  (low to high)
• Uses carrier proteins similar to facilitated
  diffusion
• Requires the use of ATP

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Active Transport

• Sodium-Potassium Pump
• Tranports Sodium (Na) and Potassium (K) up their
  concentration gradient
• By using ATP, the Na-K Pump pumps 3 sodium ion
  out of the cell and brings two potassium ions in

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Active Transport

• Movement in Vesicles
• Molecules that are too big to be brought into the
  cell or leave the cell are moved in other ways
• Endocytosis materials are come IN to the cell
• Exocytosis Material EXIT the cell

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Active Transport

• Endocytosis
• Items are enclosed by a portion of the cell
  membrane
• Cell Membrane forms a pouch
• The pouch pinches off and forms a vesicle

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Active Transport

• Endocytosis
• Once the vesicle is formed, it can be transported
  within the cell
• It can attach to a lysosome to be digested
• Fuse with other organelles

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Active Transport

• Endocytosis
• Pinocytosis (cell drinking) liquids and
  solutions are brought into the cell
• Phagocytosis (cell eating) large particles or
  entire cells are brought in to the cell
• Phagocytes ingest bacteria then fuse with
  lysosomes

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Active Transport

• Exocytosis
• Works in reverse to endocytosis
• Transports wastes, proteins, toxins, and other
  materials out of the cell

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Assignment

• Section 2 Review
• p. 106 (1-6) Q A

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Bellringer 3
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Bellringer 4

• Standardized Test Preparation
• p. 109 (5-7) Q A

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Assignment Chapter 5 Review p. 108 (5-19) Q A