| 单词 | plasma membrane |
| 例句 | Free cholesterol is drawn into the cell's plasma membrane -- the external boundary of the cell -- by a protein called NPC1L1. Researchers identify previously unknown step in cholesterol absorption in the gut 2023-11-09T05:00:00Z Four of the compounds -- including two of the newly identified ones -- were effective at destroying the plasma membrane of this fungus, causing its cells to leak and preventing it from forming biofilms. Sunflower extract fights fungi to keep blueberries fresh 2023-10-25T04:00:00Z The cytoplasm is encased by a plasma membrane, which in turn is encased by a cell wall. Fundamentals of Biology 2015-01-01T00:00:00Z A cell’s plasma membrane defines the boundary of the cell and determines the nature of its contact with the environment. Concepts of Biology 2013-04-25T00:00:00Z Another interesting biological example dealing with electric potential is found in the cell’s plasma membrane. College Physics for AP Courses 2015-08-12T00:00:00Z Phospholipids are responsible for the dynamic nature of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Plant cells have a rigid cell wall that is external to the plasma membrane, chloroplasts, plasmodesmata, and plastids used for storage, and a large central vacuole, whereas animal cells do not. Environmental Biology 2018-09-06T00:00:00Z The cell wall is a thick layer of peptidoglycan that exists outside the plasma membrane. Fundamentals of Biology 2015-01-01T00:00:00Z The plasma membrane must be sufficiently flexible to allow certain cells, such as red blood cells and white blood cells, to change shape as they pass through narrow capillaries. Concepts of Biology 2013-04-25T00:00:00Z Outside the plasma membrane of the axon is the myelin sheath, which is composed of the tightly wrapped plasma membrane of a Schwann cell. Anatomy and Physiology 2013-06-19T00:00:00Z The receptor, in turn, changes the conformation of the microfilaments positioned just inside the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Scott Emr, a yeast biologist at Cornell University in Ithaca, New York, encountered this when he began studying contact sites between the ER and the plasma membrane. How secret conversations inside cells are transforming biology 2019-03-10T05:00:00Z In Gram-negative bacteria, a thin peptidoglycan cell wall is sandwiched between an outer and an inner plasma membrane. Fundamentals of Biology 2015-01-01T00:00:00Z The plasma membrane also carries receptors, which are attachment sites for specific substances that interact with the cell. Concepts of Biology 2013-04-25T00:00:00Z Cells of the parathyroid gland have plasma membrane receptors for calcium. Anatomy and Physiology 2013-06-19T00:00:00Z When protein receptors on the surface of the plasma membrane of an animal cell bind to a substance in the extracellular matrix, a chain of reactions begins that changes activities taking place within the cell. Biology for AP Courses 2022-06-09T00:00:00Z The team showed12 that a protein involved in insulin secretion serves as a tether between the ER and the plasma membrane in rat pancreatic cells. How secret conversations inside cells are transforming biology 2019-03-10T05:00:00Z Indigestible waste material is ejected from the cell when an exocytic vesicle fuses with the plasma membrane. Fundamentals of Biology 2015-01-01T00:00:00Z Receptors on the plasma membrane’s exterior surface interact with hormones or neurotransmitters, and allow their messages to be transmitted into the cell. Concepts of Biology 2013-04-25T00:00:00Z Figure 10.4 Muscle Fiber A skeletal muscle fiber is surrounded by a plasma membrane called the sarcolemma, which contains sarcoplasm, the cytoplasm of muscle cells. Anatomy and Physiology 2013-06-19T00:00:00Z Prokaryotic and eukaryotic cells are surrounded by a plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Other voltage indicators are mutated versions of microbial rhodopsins, fluorescent molecules that cause a change in voltage across the plasma membrane in response to light. A new way to capture the brain’s electrical symphony 2018-09-18T04:00:00Z For example, they are enclosed by a plasma membrane and have a nucleus and other membrane-bound organelles. Fundamentals of Biology 2015-01-01T00:00:00Z The model has evolved somewhat over time, but still best accounts for the structure and functions of the plasma membrane as we now understand them. Concepts of Biology 2013-04-25T00:00:00Z A platelet is not a cell but rather a fragment of the cytoplasm of a cell called a megakaryocyte that is surrounded by a plasma membrane. Anatomy and Physiology 2013-06-19T00:00:00Z In preparation for phagocytosis, a portion of the inward-facing surface of the plasma membrane becomes coated with a protein called clathrin, which stabilizes this section of the membrane. Biology for AP Courses 2022-06-09T00:00:00Z It kills by damaging most any bacterium’s plasma membrane, causing it to spill its contents and deflate. A powerful new weapon against drug-resistant bacteria was inspired by the human body 2018-01-10T05:00:00Z Unfolded proteins create stress on the cell, and you potentially create situations where you now put less assembled proteins in the plasma membrane. Map of body’s protein-folding machinery wins major prize 2014-09-08T04:00:00Z Figure 3.18 The fluid mosaic model of the plasma membrane structure describes the plasma membrane as a fluid combination of phospholipids, cholesterol, proteins, and carbohydrates. Concepts of Biology 2013-04-25T00:00:00Z One of the sperm will then break through to the oocyte’s plasma membrane and release its haploid nucleus into the oocyte. Anatomy and Physiology 2013-06-19T00:00:00Z When accessible nutrients from the degradation of the vesicular contents have been extracted, the newly formed endosome merges with the plasma membrane and releases its contents into the extracellular fluid. Biology for AP Courses 2022-06-09T00:00:00Z Our Letter reported that PIN transporters for the plant hormone auxin are initially delivered to the plasma membrane in a non-polar manner and that their polar distribution requires endocytosis. Retraction: Generation of cell polarity in plants links endocytosis, auxin distribution and cell fate decisions : Nature : Nature Publishing Group 2014-07-15T04:00:00Z Oligodendrocytes generate multiple myelin sheaths, lipid-rich extensions of specialized plasma membrane that spirally coat condensed layers around neurons. [Perspective] A New Wrap for Neuronal Activity? 2014-05-01T18:25:58.611Z Thus, both surfaces of the plasma membrane are hydrophilic. Concepts of Biology 2013-04-25T00:00:00Z They are cylindrical apical surface extensions of the plasma membrane of the mucosa’s epithelial cells, and are supported by microfilaments within those cells. Anatomy and Physiology 2013-06-19T00:00:00Z In exocytosis, waste material is enveloped in a membrane that fuses with the interior of the plasma membrane via attachment proteins. Biology for AP Courses 2022-06-09T00:00:00Z The various wounding methods used here revealed a systematic recruitment of ESCRTs to the plasma membrane. [Research Article] ESCRT Machinery Is Required for Plasma Membrane Repair 2014-02-27T19:26:19.391Z The molecular mechanism by which the plasma membrane initiates changes in the cell expansion rate remains elusive. [Report] A Peptide Hormone and Its Receptor Protein Kinase Regulate Plant Cell Expansion 2014-01-23T19:26:20.724Z The solution to moving polar substances and other substances across the plasma membrane rests in the proteins that span its surface. Concepts of Biology 2013-04-25T00:00:00Z There are an estimated 200 million microvilli per square millimeter of small intestine, greatly expanding the surface area of the plasma membrane and thus greatly enhancing absorption. Anatomy and Physiology 2013-06-19T00:00:00Z In endocytosis, waste material is enveloped in a membrane that fuses with the interior of the plasma membrane via attachment proteins. Biology for AP Courses 2022-06-09T00:00:00Z It remains unclear whether these phenomena are linked to local plasma membrane damage and whether ESCRT-III proteins are involved in these processes. [Research Article] ESCRT Machinery Is Required for Plasma Membrane Repair 2014-02-27T19:26:19.391Z Centrosome docking at the plasma membrane also occurs during cilia formation. [Report] Hedgehog Signaling Controls T Cell Killing at the Immunological Synapse 2013-12-05T18:57:29.425Z Because cells contain proteins, most of which are negatively charged, and because ions move into and out of cells, there is an electrical gradient, a difference of charge, across the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z In contrast to the water-soluble nutrients, lipid-soluble nutrients can diffuse through the plasma membrane. Anatomy and Physiology 2013-06-19T00:00:00Z In exocytosis, waste material is enveloped in a membrane that fuses with the exterior of the plasma membrane via attachment proteins. Biology for AP Courses 2022-06-09T00:00:00Z Ms. Alford worked in her classroom last Tuesday, carefully hanging an animal-cell poster illustrating the plasma membrane and Golgi complex with rolled masking tape. Atlanta School Year Begins Amid a Testing Scandal 2011-08-08T02:50:11Z Enucleation results from asymmetric cell division in which the condensed nucleus, surrounded by a plasma membrane, buds off from the immature erythroblast. Editors' Choice 2011-01-20T19:25:02.033Z A particle enveloped in membrane fuses with the interior of the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z This conversion step requires one ATP and essentially traps the glucose in the cell, preventing it from passing back through the plasma membrane, thus allowing glycolysis to proceed. Anatomy and Physiology 2013-06-19T00:00:00Z Explain what impact arsenic poisoning may have on components of the plasma membrane and transport that result in CF like symptoms. Biology for AP Courses 2022-06-09T00:00:00Z Further study will examine how the Gag complex travels from the nucleus to the plasma membrane. Retrovirus Replication Process Different Than Thought 2010-07-20T14:32:00Z Tyrosine kinase receptors are pairs of proteins that span the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Ribosomes are found in the cytoplasm or are attached to the cytoplasmic side of the plasma membrane or endoplasmic reticulum. Concepts of Biology 2013-04-25T00:00:00Z The plasma membrane of that sperm then fuses with the oocyte’s plasma membrane, and the head and mid-piece of the “winning” sperm enter the oocyte interior. Anatomy and Physiology 2013-06-19T00:00:00Z They are hormones that diffuse through the plasma membrane to stimulate protein production. Biology for AP Courses 2022-06-09T00:00:00Z Turgor in the guard cells is regulated by the active transport of several ions, including K+ and H+, across the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z A contractile ring composed of actin filaments forms just inside the plasma membrane at the former metaphase plate. Biology for AP Courses 2022-06-09T00:00:00Z The modern understanding of the plasma membrane is referred to as the fluid mosaic model. Concepts of Biology 2013-04-25T00:00:00Z Antibodies have no effect on viruses or other intracellular pathogens once they enter the cell, since antibodies are not able to penetrate the plasma membrane of the cell. Anatomy and Physiology 2013-06-19T00:00:00Z Cells grown in the laboratory are mixed with a dye molecule that is unable to pass through the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z While some of these vesicles deposit their contents into other parts of the cell where they will be used, other secretory vesicles fuse with the plasma membrane and release their contents outside the cell. Biology for AP Courses 2022-06-09T00:00:00Z The invaginated section, with the pathogen inside, then pinches itself off from the plasma membrane and becomes a vesicle. Biology for AP Courses 2022-06-09T00:00:00Z In phagocytosis, a portion of the membrane invaginates and flows around the particle, eventually pinching off and leaving the particle wholly enclosed by an envelope of plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z The plasma membrane is selectively permeable, meaning some molecules can freely enter or leave the cell. Biology for AP Courses 2022-06-09T00:00:00Z A virus uses a plasma membrane to connect to a host cell. Biology for AP Courses 2022-06-09T00:00:00Z One example of a molecule that assists other molecules across the plasma membrane is a protein called NPC1. Biology for AP Courses 2022-06-09T00:00:00Z This protein is involved in moving cholesterol and other types of fats across the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane is drawn in by a ring of actin fibers contracting just inside the membrane. Concepts of Biology 2013-04-25T00:00:00Z The model has evolved somewhat over time, but it still best accounts for the structure and functions of the plasma membrane as we now understand them. Biology for AP Courses 2022-06-09T00:00:00Z Most prokaryotes have a cell wall that lies outside the boundary of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Figure 5.2 The fluid mosaic model of the plasma membrane describes the plasma membrane as a fluid combination of phospholipids, cholesterol, and proteins. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane of human red blood cells is 30 percent lipid. Biology for AP Courses 2022-06-09T00:00:00Z Phospholipids are the major constituent of the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z Carbohydrates are present only on the exterior surface of the plasma membrane and are attached to proteins, forming glycoproteins, or attached to lipids, forming glycolipids. Biology for AP Courses 2022-06-09T00:00:00Z A mechanosensitive channel is connected to the plasma membrane and the cytoskeleton by hair- like tethers. Biology for AP Courses 2022-06-09T00:00:00Z This characteristic is vital to the structure of a plasma membrane because, in water, phospholipids tend to become arranged with their hydrophobic tails facing each other and their hydrophilic heads facing out. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane is selectively permeable to polar molecules, and a transport protein is required for larger molecules. Biology for AP Courses 2022-06-09T00:00:00Z Most prokaryotes have a cell wall lying outside the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z The plasma membrane is permeable to all polar molecules, but a transport protein is required. Biology for AP Courses 2022-06-09T00:00:00Z Because amino acid-derived hormones and polypeptide hormones are not lipid-soluble, they bind to plasma membrane hormone receptors located on the outer surface of the membrane. Biology for AP Courses 2022-06-09T00:00:00Z As sodium ion concentrations build outside of the plasma membrane because of the action of the primary active transport process, an electrochemical gradient is created. Biology for AP Courses 2022-06-09T00:00:00Z There are different variations of endocytosis, but all share a common characteristic: The plasma membrane of the cell invaginates, forming a pocket around the target particle. Biology for AP Courses 2022-06-09T00:00:00Z When neurotransmitter molecules bind to receptors located on a neuron’s dendrites, the neurotransmitter opens ion channels in the dendrite’s plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z The pocket pinches off, resulting in the particle being contained in a newly created intracellular vesicle formed from the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z They are transported across the plasma membrane of target cells and bind to receptors on the mitochondria resulting in increased ATP production. Biology for AP Courses 2022-06-09T00:00:00Z This process uses a coating protein, called caveolin, on the cytoplasmic side of the plasma membrane, which performs a similar function to clathrin. Biology for AP Courses 2022-06-09T00:00:00Z The cavities in the plasma membrane that form the vacuoles have membrane receptors and lipid rafts in addition to caveolin. Biology for AP Courses 2022-06-09T00:00:00Z They have no plasma membrane, internal organelles, or metabolic processes, and they do not divide. Concepts of Biology 2013-04-25T00:00:00Z The plasma membrane is composed of a bilayer of phospholipids, with their hydrophobic, fatty acid tails in contact with each other. Biology for AP Courses 2022-06-09T00:00:00Z A lipid-derived hormone because it is fat insoluble and therefore able to bind to receptors on the outer surface of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z It fuses with and becomes part of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Fluidity helps in providing mechanical strength to the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Figure 16.18 A skeletal muscle fiber is surrounded by a plasma membrane called the sarcolemma, with a cytoplasm called the sarcoplasm. Concepts of Biology 2013-04-25T00:00:00Z List four components of a plasma membrane and explain their function. Biology for AP Courses 2022-06-09T00:00:00Z A polypeptide-derived hormone because it is fat insoluble and therefore binds to receptors on the outer surface of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Endocytosis involves the opsonization of a receptor and its ligand in clathrin-coated vesicles, along with the inward budding of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z In endocytosis, waste material is enveloped in a membrane that fuses with the interior of the plasma membrane via attachment proteins. Biology for AP Courses 2022-06-09T00:00:00Z Some organisms, such as plants, fungi, bacteria, and some protists, have cell walls that surround the plasma membrane and prevent cell lysis. Concepts of Biology 2013-04-25T00:00:00Z Opsonin stabilizes the inward facing surface of the plasma membrane, which engulfs the antigen, whereas clathrin marks the antigen for phagocytosis by neutrophils. Biology for AP Courses 2022-06-09T00:00:00Z Figure 29.34 A skeletal muscle cell is surrounded by a plasma membrane called the sarcolemma with a cytoplasm called the sarcoplasm. Biology for AP Courses 2022-06-09T00:00:00Z In prokaryotes, such as cyanobacteria, the process is less localized and occurs within folded membranes, extensions of the plasma membrane, and in the cytoplasm. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane is permeable to the nonpolar, uncharged carbon dioxide molecule. Biology for AP Courses 2022-06-09T00:00:00Z In plant cells, a cleavage furrow is not possible because of the rigid cell walls surrounding the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z Cell signaling pathways begin when the ligand binds to a receptor, a protein that is embedded in the plasma membrane of the target cell or found in the cell cytoplasm. Biology for AP Courses 2022-06-09T00:00:00Z The small size and large surface area of red blood cells allows for rapid diffusion of oxygen and carbon dioxide across the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Some membrane receptors work by changing conformation so that certain ions, such as Na+ and K+, can pass through the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Other membrane receptors interact with a G-protein on the cytoplasmic side of the plasma membrane, which causes a series of reactions inside the cell. Biology for AP Courses 2022-06-09T00:00:00Z The fluidity of the plasma membrane is necessary for the activities of certain enzymes and transport molecules within the membrane. Concepts of Biology 2013-04-25T00:00:00Z Figure 9.4 Hydrophobic signaling molecules typically diffuse across the plasma membrane and interact with intracellular receptors in the cytoplasm. Biology for AP Courses 2022-06-09T00:00:00Z Cholesterol is a type of steroid in animal cells’ plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Sometimes these modifications can regulate where a protein is found in the cell—for example, in the nucleus, the cytoplasm, or attached to the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Cardiac muscle tissue also has intercalated discs, specialized regions running along the plasma membrane that join adjacent cardiac muscle cells and assist in passing an electrical impulse from cell to cell. Biology for AP Courses 2022-06-09T00:00:00Z Integral proteins are embedded in the plasma membrane and may span all or part of the membrane. Concepts of Biology 2013-04-25T00:00:00Z These molecules can pass through the plasma membrane of the cell and enter the epithelial cells of the intestinal lining. Biology for AP Courses 2022-06-09T00:00:00Z It is a component of the plasma membrane of animal cells and is found within the phospholipid bilayer. Biology for AP Courses 2022-06-09T00:00:00Z Neurons and muscle cells maintain a high concentration gradient of potassium ions across the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Disturbance of these dendrites by compressing them or bending them opens gated ion channels in the plasma membrane of the sensory neuron, changing its electrical potential. Biology for AP Courses 2022-06-09T00:00:00Z However, the substances that undergo facilitated transport would otherwise not diffuse easily or quickly across the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z Because these hormones are water-soluble and insoluble in lipids, they cannot pass through the plasma membrane of cells; their receptors are found on the surface of the target cells. Biology for AP Courses 2022-06-09T00:00:00Z Being the outermost structure in animal cells, the plasma membrane is responsible for the transport of materials and cellular recognition and it is involved in cell-to-cell communication. Biology for AP Courses 2022-06-09T00:00:00Z The steroid hormones pass through the plasma membrane of a target cell and adhere to intracellular receptors residing in the cytoplasm or in the nucleus. Biology for AP Courses 2022-06-09T00:00:00Z The hormones diffuse across both the plasma membrane and the nuclear envelope, then bind to receptors in the nucleus. Biology for AP Courses 2022-06-09T00:00:00Z Lipids are also the building blocks of many hormones and are an important constituent of the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z Lipid insoluble hormones bind to receptors on the outer surface of the plasma membrane, via plasma membrane hormone receptors. Biology for AP Courses 2022-06-09T00:00:00Z Before turning to organelles, let’s first examine two important components of the cell: the plasma membrane and the cytoplasm. Biology for AP Courses 2022-06-09T00:00:00Z Most of the released T3 and T4 becomes attached to transport proteins in the bloodstream and is unable to cross the plasma membrane of cells. Biology for AP Courses 2022-06-09T00:00:00Z Hormones can affect cells directly through intracellular hormone receptors or indirectly through plasma membrane hormone receptors. Biology for AP Courses 2022-06-09T00:00:00Z Before discussing the functions of organelles within a eukaryotic cell, let us first examine two important components of the cell: the plasma membrane and the cytoplasm. Concepts of Biology 2013-04-25T00:00:00Z Lipid insoluble hormones bind to receptors on the plasma membrane surface and trigger a signaling pathway to change the cell’s activities by inducing production of various cell products that affect the cell in the short-term. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane controls the passage of organic molecules, ions, water, and oxygen into and out of the cell. Biology for AP Courses 2022-06-09T00:00:00Z Hormones only affect cells that have plasma membrane receptors. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane of a skeletal muscle fiber is called the sarcolemma. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane regulates the passage of some substances, such as organic molecules, ions, and water, preventing the passage of some to maintain internal conditions, while actively bringing in or removing others. Concepts of Biology 2013-04-25T00:00:00Z Ribosomes are either found in the cytoplasm or attached to the cytoplasmic side of the plasma membrane or endoplasmic reticulum. Biology for AP Courses 2022-06-09T00:00:00Z Passage through the channel allows polar compounds to avoid the nonpolar central layer of the plasma membrane that would otherwise slow or prevent their entry into the cell. Biology for AP Courses 2022-06-09T00:00:00Z The vesicle travels from the Golgi to the plasma membrane to release the protein outside. Biology for AP Courses 2022-06-09T00:00:00Z The vesicle travels from the endoplasmic reticulum to the plasma membrane, and returns to the Golgi apparatus to get modified. Biology for AP Courses 2022-06-09T00:00:00Z They also maintain the structure of microvilli, the extensive folding of the plasma membrane found in cells dedicated to absorption. Concepts of Biology 2013-04-25T00:00:00Z Ribosomes are either found in the cytoplasm or attached to the cytoplasmic side of the plasma membrane or endoplasmic reticulum. Biology for AP Courses 2022-06-09T00:00:00Z This selectivity adds to the overall selectivity of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z These reactions occur on the plasma membrane of bacteria. Biology for AP Courses 2022-06-09T00:00:00Z However, because of its mosaic nature, a very fine needle can easily penetrate a plasma membrane without causing it to burst, and the membrane will flow and self-seal when the needle is extracted. Biology for AP Courses 2022-06-09T00:00:00Z The electron transport chain is present in multiple copies in the inner mitochondrial membrane of eukaryotes and in the plasma membrane of prokaryotes. Concepts of Biology 2013-04-25T00:00:00Z The plasma membrane is impermeable to polar molecules, so transport proteins are required. Biology for AP Courses 2022-06-09T00:00:00Z Figure 5.10 Some substances are able to move down their concentration gradient across the plasma membrane with the aid of carrier proteins. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane is selectively permeable to all polar molecules and a transport protein is never required for them. Biology for AP Courses 2022-06-09T00:00:00Z Carbohydrates, attached to lipids or proteins, are also found on the exterior surface of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z The pocket pinches off, resulting in the particle being contained in a newly created vacuole that is formed from the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z Figure 5.7 The exterior surface of the plasma membrane is not identical to the interior surface of the same membrane. Biology for AP Courses 2022-06-09T00:00:00Z A red blood cell will burst, or lyse, when it swells beyond the plasma membrane’s capability to expand. Biology for AP Courses 2022-06-09T00:00:00Z While some polar molecules connect easily with the outside of a cell, they cannot readily pass through the lipid core of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Surface area and thickness of the plasma membrane: Increased surface area increases the rate of diffusion, whereas a thicker membrane reduces it. Biology for AP Courses 2022-06-09T00:00:00Z The particles bind to the proteins and the plasma membrane invaginates, bringing the substance and the proteins into the cell. Concepts of Biology 2013-04-25T00:00:00Z The material being transported is first attached to protein or glycoprotein receptors on the exterior surface of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Waste material is enveloped in a membrane and fuses with the interior of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z The electron transport chain is present in multiple copies in the inner mitochondrial membrane of eukaryotes and the plasma membrane of prokaryotes. Biology for AP Courses 2022-06-09T00:00:00Z Here, they bind ligand molecules that cross the plasma membrane; these receptor-ligand complexes move to the nucleus and interact directly with cellular DNA. Biology for AP Courses 2022-06-09T00:00:00Z The endomembrane system includes the nuclear envelope, the endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, as well as the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z The molecules are hydrophilic and cannot penetrate the hydrophobic interior of the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z A cascade of events that occurs upon insulin binding to a receptor in the plasma membrane causes GLUT4-containing vesicles to fuse with the plasma membrane so that glucose may be transported into the cell. Biology for AP Courses 2022-06-09T00:00:00Z The bacterial chromosome is attached to the plasma membrane at about the midpoint of the cell. Biology for AP Courses 2022-06-09T00:00:00Z Cholesterol is a type of steroid and is an important constituent of the plasma membrane, where it helps to maintain the fluid nature of the membrane. Biology for AP Courses 2022-06-09T00:00:00Z Figure 3.13 Why does the cis face of the Golgi not face the plasma membrane? Concepts of Biology 2013-04-25T00:00:00Z The plasma membrane separates the interior and the exterior of the cell. Biology for AP Courses 2022-06-09T00:00:00Z This type of receptor spans the plasma membrane and performs signal transduction, in which an extracellular signal is converted into an intracellular signal. Biology for AP Courses 2022-06-09T00:00:00Z If the cell grows too large, the plasma membrane will not have sufficient surface area to support the rate of diffusion required for the increased volume. Biology for AP Courses 2022-06-09T00:00:00Z Like prokaryotes, all eukaryotic cells have a plasma membrane, cytoplasm, ribosomes, and DNA. Biology for AP Courses 2022-06-09T00:00:00Z This folding increases the surface area of the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z The vesicle travels from the endoplasmic reticulum to get embedded in plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z In order to interact with the phospholipid fatty acid tails that form the center of the plasma membrane, many of the amino acids in the membrane-spanning region are hydrophobic in nature. Biology for AP Courses 2022-06-09T00:00:00Z Plant cells and animal cells both have a rigid plasma membrane as well as cytoplasm which is the gel-like solution that fills the cell. Biology for AP Courses 2022-06-09T00:00:00Z If the cell grows too large, the plasma membrane will not have sufficient surface area to support the rate of diffusion required for the increased volume. Biology for AP Courses 2022-06-09T00:00:00Z The structure of the plasma membrane contributes to these functions, but it also presents some problems. Concepts of Biology 2013-04-25T00:00:00Z The plasma membrane must be very flexible to allow certain cells, such as red blood cells and white blood cells, to change shape as they pass through narrow capillaries. Biology for AP Courses 2022-06-09T00:00:00Z Figure 9.5 Gated ion channels form a pore through the plasma membrane that opens when the signaling molecule binds. Biology for AP Courses 2022-06-09T00:00:00Z These are the more obvious functions of a plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Among the most sophisticated functions of the plasma membrane is the ability to transmit signals by means of complex, integral proteins known as receptors. Biology for AP Courses 2022-06-09T00:00:00Z Rather, the chromosome loop is replicated, and the two resulting copies attached to the plasma membrane move apart as the cell grows in a process called binary fission. Concepts of Biology 2013-04-25T00:00:00Z They theorized that the structure of the plasma membrane resembles a sandwich, with protein being analogous to the bread, and lipids being analogous to the filling. Biology for AP Courses 2022-06-09T00:00:00Z Because these molecules are small and hydrophobic, they can diffuse directly across the plasma membrane into the cell, where they interact with internal receptors. Biology for AP Courses 2022-06-09T00:00:00Z A new model that better explains both the microscopic observations and the function of that plasma membrane was proposed by S.J. Biology for AP Courses 2022-06-09T00:00:00Z The fluid mosaic model describes the structure of the plasma membrane as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character. Biology for AP Courses 2022-06-09T00:00:00Z Figure 17.6 Influenza virus is packaged in a viral envelope, which fuses with the plasma membrane. Concepts of Biology 2013-04-25T00:00:00Z In living systems, diffusion of substances into and out of cells is mediated by the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z It is able to diffuse directly across the plasma membrane, and one of its roles is to interact with receptors in smooth muscle and induce relaxation of the tissue. Biology for AP Courses 2022-06-09T00:00:00Z In phagocytosis, a portion of the membrane invaginates and flows around the particle, eventually pinching off and leaving the particle entirely enclosed by an envelope of plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane invaginates and pinches off, producing a small envelope of fluid from outside the cell. Biology for AP Courses 2022-06-09T00:00:00Z These reactions, involving enzymes from the acrosome, allow the sperm plasma membrane to fuse with the egg plasma membrane and permit the sperm nucleus to transfer into the ovum. Concepts of Biology 2013-04-25T00:00:00Z Why is it advantageous for the plasma membrane to be fluid in nature? Biology for AP Courses 2022-06-09T00:00:00Z Present in small concentrations in the plasma membrane, inositol phospholipids are lipids that can also be converted into second messengers. Biology for AP Courses 2022-06-09T00:00:00Z Opsonin marks the antigen for phagocytosis by neutrophils, whereas clathrin stabilizes the inward facing surface of the plasma membrane, which engulfs the antigen. Biology for AP Courses 2022-06-09T00:00:00Z Fatty acid compositions of the plasma membrane of E. coli were incubated at the temperatures shown. Biology for AP Courses 2022-06-09T00:00:00Z Some organisms, such as plants, fungi, bacteria, and some protists, have cell walls that surround the plasma membrane and prevent cell lysis in a hypotonic solution. Biology for AP Courses 2022-06-09T00:00:00Z The plasma membrane can only expand to the limit of the cell wall, so the cell will not lyse. Biology for AP Courses 2022-06-09T00:00:00Z Using signal transduction pathways, receptors in the plasma membrane produce a variety of effects on the cell. Biology for AP Courses 2022-06-09T00:00:00Z Ion channel-linked receptors, when bound to their ligands, form a pore through the plasma membrane through which certain ions can pass. Biology for AP Courses 2022-06-09T00:00:00Z G-protein-linked receptors interact with a G-protein on the cytoplasmic side of the plasma membrane, promoting the exchange of bound GDP for GTP and interacting with other enzymes or ion channels to transmit a signal. Biology for AP Courses 2022-06-09T00:00:00Z Growth factor proteins arriving at the dividing cell’s plasma membrane can trigger the cell to begin dividing. Biology for AP Courses 2022-06-09T00:00:00Z They therefore lack most of the components of cells, such as organelles, ribosomes, and the plasma membrane. Biology for AP Courses 2022-06-09T00:00:00Z Multicellular organisms involve receptors for signaling; single-celled organisms communicate by fusion of plasma membrane with the nearby cells. Biology for AP Courses 2022-06-09T00:00:00Z |
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