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Chapter 15. Cell Processes. Chapter Preview Section 15-1 – Chemistry of Living Things Section 15-2 – Cell Transport Section 15-3 – Energy in Cells. 15 2. Cell Transport. Vocabulary diffusion equilibrium osmosis passive transport active transport endocytosis exocytosis.
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Chapter15 Cell Processes Chapter Preview Section 15-1 – Chemistry of Living Things Section 15-2 – Cell Transport Section 15-3 – Energy in Cells
15 2 Cell Transport • Vocabulary • diffusion • equilibrium • osmosis • passive transport • active transport • endocytosis • exocytosis • What You’ll Learn • The function of a selectively permeable membrane • The processes of diffusion and osmosis • The differences between passive transport and active transport Copy these words into your notebooks. Label them 15-2
Skin Deep • Supermarkets use water misting to keep their produce fresh. • Not all the water stays on the skin of these fruits and vegetables. • Some of it is absorbed through the outer skin of the produce. WHY?
In what ways are cell membranes selectively permeable? • Just like a screen on a window allows air in, but keeps bugs out, a cell membrane allows some things to pass through, but not others.
Diffusion • When molecules move from areas of higher concentration (where there are more of them) to an area of lower concentration (where there are less of them). Once the two areas are equally mixed (diffused) , then the solution has reached a state of EQUILIBRIUM
Osmosis • The diffusion of water through a membrane
Types of Transport • Passive Transport • The movement of substances through the cell membrane without the use of cellular energy • Active Transport • The movement of substances through the cell membrane by using cellular energy • Endocytosis • The process whereby larger molecules and bacteria enter a cell by having the cell surround it and “pinch it off” • Exocytosis • Opposite of endocytosis
Types of Transport • Passive Transport • The movement of substances through the cell membrane without the use of cellular energy • Substances too large to simply pass through the cell membrane require the help of transport protein molecules to pass through. • The molecules that help substances move through the cell membrane are called transport proteins. • This assistance is also called facilitated diffusion. • Both diffusion and facilitated diffusion are types of passive transport
Types of Transport • Active Transport • The movement of substances through the cell membrane with the use of cellular energy • Sometimes a substance is needed in a cell even though the amount of that substance inside the cell is already greater than the amount outside the cell. • In such a case, the substance cannot move into the cell by diffusion or facilitated diffusion. In order to move the substance into the cell, cellular energy must be used to make the process happen. • Active transport also involves transport proteinsto help substances move through the cell membrane.
Active Transport • Uses cellular energy (also called ATP) to transport proteins across the cellular membrane
Section Assessment • In what ways are cell membranes selectively permeable? • Compare and contrast osmosis and diffusion. • Identify the molecules that help substances move through the cell membrane. • Think critically… Why are fresh fruits and vegetables sprinkled with water in produce markets?