Cell Transport Mechanisms
11M01_ZAO2177_01_SE_CH01.QXD
3/4/11
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Cell Transport Mechanisms and Permeability
P R E - L A B Q U I Z 1. Circle the correct term. A passive process, diffusion / osmosis is the movement of solute molecules from an area of greater concentration to an area of lesser concentration. 2. A solution surrounding a cell is hypertonic if: a. it contains fewer nonpenetrating solute particles than the interior of the cell. b. it contains more nonpenetrating solute particles than the interior of the cell. c. it contains the same amount of nonpenetrating solute particles as the interior of the cell. 3. Which of the following would require an input of energy? a. diffusion b. filtration c. osmosis d. vesicular transport 4. Circle the correct term. In pinocytosis / phagocytosis, parts of the plasma membrane and cytoplasm expand and flow around a relatively large or solid material and engulf it. 5. Circle the correct term. In active / passive processes, the cell provides energy in the form of ATP to power the transport process.
Exercise Overview
The molecular composition of the plasma membrane allows it to be selective about what passes through it. It allows nutrients and appropriate amounts of ions to enter the cell and keeps out undesirable substances. For that reason, we say the plasma membrane is selectively permeable. Valuable cell proteins and other substances are kept within the cell, and metabolic wastes pass to the exterior. Transport through the plasma membrane occurs in two basic ways: either passively or actively. In passive processes, the transport process is driven by concentration or pressure differences (gradients) between the interior and exterior of the cell. In active processes, the cell provides energy (ATP) to power the transport. Two key passive processes of membrane transport are diffusion and filtration. Diffusion is an important transport process for every cell in the body. Simple
3/4/11
1:36 AM
Page 1
E
X
E
R
C
I
S
E
1
Cell Transport Mechanisms and Permeability
P R E - L A B Q U I Z 1. Circle the correct term. A passive process, diffusion / osmosis is the movement of solute molecules from an area of greater concentration to an area of lesser concentration. 2. A solution surrounding a cell is hypertonic if: a. it contains fewer nonpenetrating solute particles than the interior of the cell. b. it contains more nonpenetrating solute particles than the interior of the cell. c. it contains the same amount of nonpenetrating solute particles as the interior of the cell. 3. Which of the following would require an input of energy? a. diffusion b. filtration c. osmosis d. vesicular transport 4. Circle the correct term. In pinocytosis / phagocytosis, parts of the plasma membrane and cytoplasm expand and flow around a relatively large or solid material and engulf it. 5. Circle the correct term. In active / passive processes, the cell provides energy in the form of ATP to power the transport process.
Exercise Overview
The molecular composition of the plasma membrane allows it to be selective about what passes through it. It allows nutrients and appropriate amounts of ions to enter the cell and keeps out undesirable substances. For that reason, we say the plasma membrane is selectively permeable. Valuable cell proteins and other substances are kept within the cell, and metabolic wastes pass to the exterior. Transport through the plasma membrane occurs in two basic ways: either passively or actively. In passive processes, the transport process is driven by concentration or pressure differences (gradients) between the interior and exterior of the cell. In active processes, the cell provides energy (ATP) to power the transport. Two key passive processes of membrane transport are diffusion and filtration. Diffusion is an important transport process for every cell in the body. Simple