脂和生物膜ppt課件-資料下載頁
2025-05-12 03:58本頁面
【正文】 e flow of water across a semipermeable membrane ? Isotonic solution: overall concentration of solutes same on both sides of membrane 被動擴(kuò)散 Simple diffusion Facilitated diffusion 促進(jìn)擴(kuò)散 （ Facilitated diffusion） Antiporters are transport proteins that transport one substance across the membrane in one direction while simultaneously transporting a second substance across the membrane in the opposite direction. Energy is required for this type of transport. Symporters are transport proteins that simultaneously transport two substances across the membrane in the same direction. Energy is required for this type of transp ? Active transport ? To use ATP to move substances across the membrane ? To be always from outside to inside even though with high concentration inside, work against gradient ? To depend on transporter proteins in plasma membrane ? Substance is not altered by transport across the membrane 主動運(yùn)輸 Schematic Illustration of Active Transport 基團(tuán)轉(zhuǎn)運(yùn)（ Group Translocation） ? A special form of active transport that occurs exclusively in prokaryotes ? An important mechanism enables the cell to accumulate various substances, is useful when nutrients are in low supply ? Substance is chemically altered during transport across the membrane ? Once substance altered and inside cell, membrane impermeable to it ? Energy supplied by high energy phosphate pounds ?Group translocation 六、胞吞（ Endocytosis）和胞吐（ Exocytosis）與形成脂囊膜有關(guān)
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