Bioloy
BIOLOGY DB015 (ASSIGNMENT)
PASSIVE AND ACTIVE TRANSPORT
GROUP MEMBERS :
ABDUL MUIN BIN ABDUL MALIK (MS1311580012)
AIMAN HAKIM BIN A.MANAP (MS1311580006)
MUHAMMAD AMIN BIN MAT SAUPI (MS
MUHAMMAD FARIZUL BIN AMRAN (MS
LECTURER : MISS AFIQAH BT MOHAMED
Q
INTRODUCTION
The various organelles and structure within a cell require a variety of subtances in order to carry out their functions. In turn, they form products; some useful and some not. Most of these substances must pass in and out of the cell.
The movement of substances in and out of a cell through the cell membrane is termed as transport across the membrane. Although the thickness of the cell membrane is only 5-10nm, it is a physical barrier to the movement of ions and molecules.
The cell membrane and other membranes within a cell are all living membranes that exhibit selective permeability. A selectively permeable membrane enables molecules of certain substances to move across it freely while excluding others.
By responding to changing environmental conditions or cellular needs, a cell membrane may also be a barrier to a substance at one time and then actively promote its passage at another. The selective permeability of cell membrane is due to the presence of the phospholipid bilayer and proteins.
Hydrophobic molecules such as carbon dioxide and oxygen can dissolve in the phospholipid bilayer and move easily across the membrane. However, it can prevent the transport of hydrophilic substances such as ions and even very small polar molecules like water, glucose and others.
Similarly, a charged atom or molecule and its surrounding envelope of water will also find the hydrophobic later of a membrane difficult to penetrate. These hydrophilic molecules will have to pass through the cell membranes via hydrophilic channels formed by protein molecules that are scattered in the phospholipid bilayer. These hydrophilic channels act as tunnels through which certain ions and polar molecules,
PASSIVE AND ACTIVE TRANSPORT
GROUP MEMBERS :
ABDUL MUIN BIN ABDUL MALIK (MS1311580012)
AIMAN HAKIM BIN A.MANAP (MS1311580006)
MUHAMMAD AMIN BIN MAT SAUPI (MS
MUHAMMAD FARIZUL BIN AMRAN (MS
LECTURER : MISS AFIQAH BT MOHAMED
Q
INTRODUCTION
The various organelles and structure within a cell require a variety of subtances in order to carry out their functions. In turn, they form products; some useful and some not. Most of these substances must pass in and out of the cell.
The movement of substances in and out of a cell through the cell membrane is termed as transport across the membrane. Although the thickness of the cell membrane is only 5-10nm, it is a physical barrier to the movement of ions and molecules.
The cell membrane and other membranes within a cell are all living membranes that exhibit selective permeability. A selectively permeable membrane enables molecules of certain substances to move across it freely while excluding others.
By responding to changing environmental conditions or cellular needs, a cell membrane may also be a barrier to a substance at one time and then actively promote its passage at another. The selective permeability of cell membrane is due to the presence of the phospholipid bilayer and proteins.
Hydrophobic molecules such as carbon dioxide and oxygen can dissolve in the phospholipid bilayer and move easily across the membrane. However, it can prevent the transport of hydrophilic substances such as ions and even very small polar molecules like water, glucose and others.
Similarly, a charged atom or molecule and its surrounding envelope of water will also find the hydrophobic later of a membrane difficult to penetrate. These hydrophilic molecules will have to pass through the cell membranes via hydrophilic channels formed by protein molecules that are scattered in the phospholipid bilayer. These hydrophilic channels act as tunnels through which certain ions and polar molecules,
References: 1. www.wikipedia.com/active_transport 2. www.wikipedia.com/passive_transport 3. Campbell, N.A. & Reece, J.B., Biology (8th Ed.), Pearson, The Benjamin Cummings Publishing Company, Inc., 2007. 4. Liew Shee Leong, Biology for Matriculation Semester 1 (3rd Ed.), Oxford Fajar Sdn. Bhd., 2011.