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- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/General_Biology_2e_(OpenStax)/01%3A_Unit_I-_The_Chemistry_of_Life/1.02%3A_The_Chemical_Foundation_of_Life/1.2.03%3A_WaterThe polarity of the water molecule and its resulting hydrogen bonding make water a unique substance with special properties that are intimately tied to the processes of life. Life originally evolved i...The polarity of the water molecule and its resulting hydrogen bonding make water a unique substance with special properties that are intimately tied to the processes of life. Life originally evolved in a watery environment, and most of an organism’s cellular chemistry and metabolism occur inside the watery contents of the cell’s cytoplasm. Understanding the characteristics of water helps to elucidate its importance in maintaining life.
- https://bio.libretexts.org/Courses/Reedley_College/Biology_for_Science_Majors_I/05%3A_Structure_and_Function_of_Plasma_Membranes/5.02%3A_Components_and_StructureAmong the most sophisticated functions of the plasma membrane is the ability to transmit signals by means of complex, integral proteins known as receptors. These proteins act both as receivers of extr...Among the most sophisticated functions of the plasma membrane is the ability to transmit signals by means of complex, integral proteins known as receptors. These proteins act both as receivers of extracellular inputs and as activators of intracellular processes. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors, and they activate intracellular response cascades when their effectors are bound.
- https://bio.libretexts.org/Courses/North_Central_State_College/BIOL_1550%3A_Microbiology_(2025)/03%3A_Macromolecules/3.07%3A_Lipids_-_Phospholipids_and_MembraneAlthough they are composed primarily of carbon and hydrogen, lipid molecules may also contain oxygen, nitrogen, sulfur, and phosphorous. Lipids serve numerous and diverse purposes in the structure and...Although they are composed primarily of carbon and hydrogen, lipid molecules may also contain oxygen, nitrogen, sulfur, and phosphorous. Lipids serve numerous and diverse purposes in the structure and functions of organisms. They can be a source of nutrients, a storage form for carbon, energy-storage molecules, or structural components of membranes and hormones. Lipids comprise a broad class of many chemically distinct compounds, the most common of which are discussed in this section.
- https://bio.libretexts.org/Courses/North_Central_State_College/BIOL_1550%3A_Microbiology_(2025)/03%3A_Macromolecules/3.06%3A_Lipids_-_TriacylglyceridesAlthough they are composed primarily of carbon and hydrogen, lipid molecules may also contain oxygen, nitrogen, sulfur, and phosphorous. Lipids serve numerous and diverse purposes in the structure and...Although they are composed primarily of carbon and hydrogen, lipid molecules may also contain oxygen, nitrogen, sulfur, and phosphorous. Lipids serve numerous and diverse purposes in the structure and functions of organisms. They can be a source of nutrients, a storage form for carbon, energy-storage molecules, or structural components of membranes and hormones. Lipids comprise a broad class of many chemically distinct compounds, the most common of which are discussed in this section.
- https://bio.libretexts.org/Courses/Cosumnes_River_College/Contemporary_Biology_(Aptekar)/02%3A_Chemistry_of_Life/2.02%3A_WaterDo you ever wonder why scientists spend time looking for water on other planets? It is because water is essential to life; even minute traces of it on another planet can indicate that life could or di...Do you ever wonder why scientists spend time looking for water on other planets? It is because water is essential to life; even minute traces of it on another planet can indicate that life could or did exist on that planet. Water is one of the more abundant molecules in living cells and the one most critical to life as we know it. Approximately 60–70 percent of your body is made up of water. Without it, life simply would not exist.
- https://bio.libretexts.org/Workbench/General_Biology_I_and_II/01%3A_Unit_I-Biology_Science_and_the_Chemistry_of_Life/1.02%3A_The_Chemical_Foundation_of_Life/1.2.03%3A_WaterThe polarity of the water molecule and its resulting hydrogen bonding make water a unique substance with special properties that are intimately tied to the processes of life. Life originally evolved i...The polarity of the water molecule and its resulting hydrogen bonding make water a unique substance with special properties that are intimately tied to the processes of life. Life originally evolved in a watery environment, and most of an organism’s cellular chemistry and metabolism occur inside the watery contents of the cell’s cytoplasm. Understanding the characteristics of water helps to elucidate its importance in maintaining life.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Biology_(Kimball)/03%3A_The_Cellular_Basis_of_Life/3.02%3A_Cell_MembranesThis page explains the plasma membrane as a universal cell feature, acting as a boundary between the interior and environment. It consists of a phospholipid bilayer with hydrophobic tails inward and i...This page explains the plasma membrane as a universal cell feature, acting as a boundary between the interior and environment. It consists of a phospholipid bilayer with hydrophobic tails inward and includes integral and peripheral membrane proteins. Integral proteins traverse the bilayer, while peripheral proteins are loosely attached. Some proteins are fixed in place by the cytoskeleton or extracellular matrix, and others are restricted by tight junctions.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/General_Biology_1e_(OpenStax)/2%3A_The_Cell/5%3A_Structure_and_Function_of_Plasma_Membranes/5.1%3A_Components_and_StructureAmong the most sophisticated functions of the plasma membrane is the ability to transmit signals by means of complex, integral proteins known as receptors. These proteins act both as receivers of extr...Among the most sophisticated functions of the plasma membrane is the ability to transmit signals by means of complex, integral proteins known as receptors. These proteins act both as receivers of extracellular inputs and as activators of intracellular processes. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors, and they activate intracellular response cascades when their effectors are bound.
- https://bio.libretexts.org/Courses/Wheaton_College_Massachusetts/Principles_of_Biochemistry/02%3A_Introduction_to_Biochemistry/2.01%3A_WaterDo you ever wonder why scientists spend time looking for water on other planets? It is because water is essential to life; even minute traces of it on another planet can indicate that life could or di...Do you ever wonder why scientists spend time looking for water on other planets? It is because water is essential to life; even minute traces of it on another planet can indicate that life could or did exist on that planet. Water is one of the more abundant molecules in living cells and the one most critical to life as we know it. Approximately 60–70 percent of your body is made up of water. Without it, life simply would not exist.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Principles_of_Biology/01%3A_Chapter_1/06%3A_The_Cell_Membrane_and_Transport/6.01%3A_The_Plasma_MembraneThe main fabric of the membrane is composed of two layers of phospholipid molecules, and the polar ends of these molecules (which look like a collection of balls in an artist’s rendition of the model)...The main fabric of the membrane is composed of two layers of phospholipid molecules, and the polar ends of these molecules (which look like a collection of balls in an artist’s rendition of the model) (Figure \PageIndex2) are in contact with aqueous fluid both inside and outside the cell.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%3A_Raven_Biology_12th_Edition/05%3A_Membranes/5.01%3A_The_Structure_of_MembranesAmong the most sophisticated functions of the plasma membrane is the ability to transmit signals by means of complex, integral proteins known as receptors. These proteins act both as receivers of extr...Among the most sophisticated functions of the plasma membrane is the ability to transmit signals by means of complex, integral proteins known as receptors. These proteins act both as receivers of extracellular inputs and as activators of intracellular processes. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors, and they activate intracellular response cascades when their effectors are bound. Occasionally, receptors are hijacked by vir
