124 Questions
What is the average estimate of cells in the adult human body?
40 trillion cells
What gives rise to all tissue types of the fetus?
Blastomeres
What encloses the animal cells and are eukaryotic with distinct, membrane-enclosed nucleus?
Cell membranes
What is a characteristic feature of prokaryotic cells?
Cell wall
What is the major polypeptide found in the electron-dense coating on the cytoplasmic surface of coated pits?
Clathrin
What type of invaginations are produced by receptor-mediated endocytosis in thin cells?
Caveolae
What directs vesicle trafficking through the endosomal compartment?
Rab proteins
Which organelle has ATP-driven H+ pumps that acidify their interior?
Lysosomes
What triggers exocytosis in many cells?
Transient increase in cytosolic Ca2+
What occurs in response to specific stimuli in regulated exocytosis?
Release of digestive enzymes from pancreatic cells
What disrupts integral proteins in cell membranes?
Detergent
What type of proteins have polypeptide chains that span the membrane multiple times?
Multipass proteins
What mainly facilitates the integration of proteins into the lipid bilayer?
Hydrophobic interactions
What contributes to the glycocalyx on both outer and inner membrane surfaces?
Parts of integral proteins
Where do carbohydrate moieties of glycoproteins and glycolipids project from?
External surface of the plasma membrane
What restricts lateral diffusion of membrane proteins?
Cytoskeletal attachments and tight junctions
What is the outermost layer of eukaryotic cells?
Plasma membrane
Which organelles are found in the cytoplasm of cells?
Mitochondria and peroxisomes
What enables muscle cells to produce forceful contractions?
Actin and myosin
What is the approximate thickness of the plasma membrane?
$7.5$ to $10$ nm
Which proteins allow for continuous exchange of information between the cytoplasm and the extracellular matrix?
$eta$-catenin
What do embryonic stem cells form from?
Fertilized egg's inner cell mass
What is the main function of the plasma membrane?
Regulation of material passage into and out of the cell
Which type of proteins are incorporated into the lipid bilayer of the plasma membrane?
Integral proteins
What is responsible for blurring the line between the interior and exterior of the cell?
Integrins in the plasma membrane
Which organelle is responsible for energy production in eukaryotic cells?
Mitochondria
Which type of filaments are found in the cytoplasm of cells?
Intermediate filaments
What type of proteins bind small molecules and translocate them across the membrane via conformational changes?
Carrier proteins
What type of transport mechanism utilizes energy from the hydrolysis of adenosine triphosphate (ATP) to move ions and other solutes across membranes?
Membrane pumps
What process involves the ingestion of particles such as bacteria or dead cell remnants?
Phagocytosis
Which type of endocytosis involves smaller invaginations of the cell membrane to entrap extracellular fluid and its dissolved contents?
Pinocytosis
What establishes a flexible boundary, protects cellular contents, and supports cell structure?
Physical barrier
What regulates entry and exit of ions, nutrients, and waste molecules through the membrane?
Selective permeability
What type of endocytosis involves high-affinity binding of ligands to their receptors causing proteins to aggregate in special membrane regions that then invaginate and pinch off internally as vesicles?
Receptor-mediated endocytosis
What type of proteins serve as receptors for various signals coming from outside cells, as parts of intercellular connections, and as selective gateways for molecules entering the cell?
Integral proteins
What type of transport mechanism allows movement of substances across membranes passively?
Diffusion, channels, and carrier proteins
What establishes and maintains an electrical charge difference across the plasma membrane?
Electrochemical gradients
What process involves fusion of membranous folds enclosing particles in an intracellular vacuole called a phagosome?
Phagocytosis
What type of endocytosis accomplishes bulk transfer of dissolved substances across the cell?
Pinocytosis
Which type of cells typically have a cell wall and lack nuclei and membranous cytoplasmic structures?
Prokaryotic cells
What do blastomeres give rise to as part of the early embryo's inner cell mass?
Histologically distinct cell types
What is the approximate number of cells in the average adult human body?
$40$ trillion cells
What is the primary function of animal cells' cytoplasm?
Support the cell structure
What is the main reason for the integration of proteins into the lipid bilayer?
Hydrophobic interactions between lipids and nonpolar amino acids
What contributes to the glycocalyx on both outer and inner membrane surfaces?
Parts of integral proteins
What is responsible for affecting membrane fluidity and being interspersed unevenly in patches called lipid rafts?
Cholesterol
What mainly facilitates the movement of small molecules across the membrane?
Diffusion or transmembrane protein channels
What restricts lateral diffusion of membrane proteins?
Cytoskeletal attachments and tight junctions
Which type of proteins have polypeptide chains that span the membrane multiple times?
Multipass proteins
Which type of endocytosis involves the interaction of caveolins with cavins?
Caveolae-mediated endocytosis
What is responsible for regulating the trafficking of endosomal vesicles?
Rab proteins
What process involves the fusion of a cytoplasmic vesicle with the plasma membrane to release macromolecules from the cell?
Exocytosis
What triggers exocytosis in many cells?
Increase in cytosolic Ca$^{2+}$ concentration
What type of membrane-bound structures may be released during exocytosis for cell-to-cell communication?
Exosomes
What regulates entry and exit of ions, nutrients, and waste molecules through the membrane?
Channel proteins
What type of transport mechanism allows movement of substances across membranes passively?
Simple diffusion
Which organelle has ATP-driven H$^+$ pumps that acidify their interior?
Lysosome
What contributes to the glycocalyx on both outer and inner membrane surfaces?
Glycoproteins and glycolipids
What type of proteins serve as receptors for various signals coming from outside cells and as selective gateways for molecules entering the cell?
Integral proteins
What mainly facilitates the integration of proteins into the lipid bilayer?
Integral proteins
Which type of endocytosis involves the binding of specific ligands to integral membrane proteins (receptors) which then invaginate and pinch off as vesicles?
Receptor-mediated endocytosis
What is responsible for the intracellular transport of endocytosed materials through the cell?
Lysosomes
Which organelle is involved in the fusion of vesicles with lysosomes for degradation?
Lysosomes
What type of proteins are involved in various functions such as receptors and transporters?
Integral membrane proteins
What is the main function of the plasma membrane?
Selective permeability
What type of transport mechanism utilizes energy from the hydrolysis of adenosine triphosphate (ATP) to move ions and other solutes across membranes?
Active transport
Which type of filaments are found in the cytoplasm of cells and contribute to the glycocalyx on both outer and inner membrane surfaces?
Intermediate filaments
What process involves substances entering the cell by enclosing them in vesicles?
Endocytosis
What do aquaporins facilitate the passage of through the plasma membrane?
Water
What type of endocytosis involves the ingestion of particles such as bacteria or dead cell remnants?
Phagocytosis
What is the approximate thickness of the plasma membrane?
2.5 to 5 nm
Which proteins are incorporated into the lipid bilayer of the plasma membrane?
Integrins
What organelles are found in the cytoplasm of cells?
Mitochondria, peroxisomes, and microtubules
Which type of cells express proteins like actin, myosin, and proteasomes?
Muscle cells
What is the main function of the plasma membrane?
Regulation of material passage into and out of the cell
Which type of filaments contribute to the glycocalyx on both outer and inner membrane surfaces?
Intermediate filaments
What are the major components of the plasma membrane?
Phospholipids, cholesterol, and proteins
What is responsible for affecting membrane fluidity and being interspersed unevenly in patches called lipid rafts?
Cholesterol
What type of stem cells are formed when the inner cell mass of a fertilized egg is cultured in laboratory conditions?
Embryonic stem cells
What is the main function of muscle cells?
Producing forceful contractions
Which type of proteins bind to the lipid bilayer or the cytoplasmic surface in eukaryotic cells?
Peripheral proteins
Which organelle is responsible for the degradation of cellular waste and foreign particles?
Lysosomes
What is the approximate number of cells in the average adult human body?
40 trillion
What type of cells lack nuclei and membranous cytoplasmic structures?
Prokaryotic cells
What is the main function of blastomeres in the early embryo's inner cell mass?
Give rise to all tissue types of the fetus
What is the process of releasing macromolecules from the cell by the fusion of a cytoplasmic vesicle with the plasma membrane called?
Exocytosis
Which type of endocytosis involves the interaction of caveolins with cavins?
Caveolae-mediated endocytosis
What are Rab proteins responsible for in membrane transport?
Regulating trafficking of endosomal vesicles
What is the process that involves the ingestion of particles such as bacteria or dead cell remnants?
Endocytosis
$H^+$ pumps that acidify their interior are found in which organelle?
$\text{Lysosomes}$
What is responsible for affecting membrane fluidity and being interspersed unevenly in patches called lipid rafts?
Cholesterol
What type of transport mechanism utilizes energy from the hydrolysis of adenosine triphosphate (ATP) to move ions and other solutes across membranes?
Primary active transport
What is responsible for regulating the trafficking of endosomal vesicles?
Rab proteins
Which type of filaments contribute to the glycocalyx on both outer and inner membrane surfaces?
Intermediate filaments
What primarily facilitates the movement of small molecules across the membrane?
Carrier proteins
What organelle has ATP-driven $H^+$ pumps that acidify their interior?
Lysosomes
What mainly facilitates the integration of proteins into the lipid bilayer?
Hydrophobic interactions between lipids and nonpolar amino acids
What contributes to the glycocalyx on both outer and inner membrane surfaces?
Carbohydrate moieties of glycoproteins and glycolipids
What is responsible for affecting membrane fluidity and being interspersed unevenly in patches called lipid rafts?
Cholesterol
What type of endocytosis involves high-affinity binding of ligands to their receptors causing proteins to aggregate in special membrane regions that then invaginate and pinch off internally as vesicles?
Receptor-mediated endocytosis
What restricts lateral diffusion of membrane proteins?
Cytoskeletal attachments and tight junctions
What type of proteins have polypeptide chains that span the membrane multiple times?
Multi-pass transmembrane proteins
Which organelle has ATP-driven $H^+$ pumps that acidify their interior?
Lysosome
What type of endocytosis involves the interaction of caveolins with cavins?
Caveolae-mediated endocytosis
What is responsible for affecting membrane fluidity and being interspersed unevenly in patches called lipid rafts?
Cholesterol
What type of proteins are incorporated into the lipid bilayer of the plasma membrane?
$\beta$-barrel proteins
What mainly facilitates the movement of small molecules across the membrane?
$\beta$-barrel proteins
What type of filaments contribute to the glycocalyx on both outer and inner membrane surfaces?
Intermediate filaments
What organelle has ATP-driven $H^+$ pumps that acidify their interior?
Lysosome
What type of endocytosis involves the interaction of caveolins with cavins?
Caveolae-mediated endocytosis
What is responsible for affecting membrane fluidity and being interspersed unevenly in patches called lipid rafts?
Cholesterol
What type of proteins are incorporated into the lipid bilayer of the plasma membrane?
$\beta$-barrel proteins
What mainly facilitates the movement of small molecules across the membrane?
$\beta$-barrel proteins
Which type of endocytosis involves the binding of specific ligands to integral membrane proteins (receptors) which then invaginate and pinch off as vesicles?
Receptor-mediated endocytosis
What is the main function of membrane pumps?
Transport of ions and other molecules against concentration gradients
What is responsible for the lateral movements of membrane proteins across the membrane?
Cytoskeleton links
Which type of transport mechanism utilizes energy from the hydrolysis of adenosine triphosphate (ATP) to move ions and other solutes across membranes?
$Na^+/K^+$ pump
What type of proteins are involved in various functions such as receptors and transporters?
Integral membrane proteins
What is the process where substances enter the cell by enclosing them in vesicles?
Endocytosis
What is responsible for the selective permeability of the plasma membrane?
Proteins
Which organelle do vesicles fuse with for degradation of endocytosed materials?
Lysosomes
What contributes to the fluid-like behavior and lateral movements of membrane proteins?
Cholesterol
Which type of endocytosis involves bulk transfer of dissolved substances across the cell?
Pinocytosis
What is responsible for affecting membrane fluidity and being interspersed unevenly in patches called lipid rafts?
Cholesterol
Study Notes
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Embryonic stem cells are formed when the inner cell mass of a fertilized egg is cultured in laboratory conditions.
-
Most cells undergo differentiation, during which they specialize in specific functions and change shape accordingly.
-
Muscle cells, for example, express proteins like actin, myosin, and proteasomes, which enable them to produce forceful contractions.
-
The cytoplasm of cells contains major organelles such as mitochondria, peroxisomes, microtubules, microfilaments (actin filaments), and intermediate filaments.
-
The plasma membrane is the outermost layer of eukaryotic cells and is composed of phospholipids, cholesterol, and proteins.
-
The plasma membrane acts as a selective barrier, regulating the passage of materials into and out of the cell and facilitating the transport of specific molecules.
-
The plasma membrane is approximately 7.5 to 10 nm thick and contains an outer layer of lipids and proteins, an inner layer of lipids and proteins, and a middle region of cholesterol.
-
Proteins, particularly integrins, allow for continuous exchange of information between the cytoplasm and the extracellular matrix, blurring the line between the interior and exterior of the cell.
-
The plasma membrane's composition includes both integral proteins, which are incorporated into the lipid bilayer, and peripheral proteins, which bind to the lipid bilayer or the cytoplasmic surface.
-
The plasma membrane allows the passage of ions and other molecules through various transport mechanisms: water (aquaporins), small molecules (carriers), and against concentration gradients (membrane pumps).
-
Membrane structure: phospholipid bilayer, proteins, cholesterol, and carbohydrates.
-
Functions of the Plasma Membrane: physical barrier, selective permeability, electrochemical gradients, communication and transport by vesicles.
-
Membrane proteins are involved in various functions, such as receptors and transporters.
-
Endocytosis: a cellular process where substances, like particles or fluids, enter the cell by enclosing them in vesicles.
- Three major types: phagocytosis, pinocytosis, and receptor-mediated endocytosis.
-
Receptor-mediated endocytosis: involves the binding of specific ligands to integral membrane proteins (receptors) which then invaginate and pinch off as vesicles.
-
Intracellular transport of endocytosed materials through the cell: vesicles fuse with lysosomes for degradation or release their contents at the cell surface through transcytosis.
-
Membrane proteins exhibit fluid-like behavior, resulting in lateral movements across the membrane, but some are anchored in place through links to the cytoskeleton.
-
Embryonic stem cells are formed when the inner cell mass of a fertilized egg is cultured in laboratory conditions.
-
Most cells undergo differentiation, during which they specialize in specific functions and change shape accordingly.
-
Muscle cells, for example, express proteins like actin, myosin, and proteasomes, which enable them to produce forceful contractions.
-
The cytoplasm of cells contains major organelles such as mitochondria, peroxisomes, microtubules, microfilaments (actin filaments), and intermediate filaments.
-
The plasma membrane is the outermost layer of eukaryotic cells and is composed of phospholipids, cholesterol, and proteins.
-
The plasma membrane acts as a selective barrier, regulating the passage of materials into and out of the cell and facilitating the transport of specific molecules.
-
The plasma membrane is approximately 7.5 to 10 nm thick and contains an outer layer of lipids and proteins, an inner layer of lipids and proteins, and a middle region of cholesterol.
-
Proteins, particularly integrins, allow for continuous exchange of information between the cytoplasm and the extracellular matrix, blurring the line between the interior and exterior of the cell.
-
The plasma membrane's composition includes both integral proteins, which are incorporated into the lipid bilayer, and peripheral proteins, which bind to the lipid bilayer or the cytoplasmic surface.
-
The text discusses various mechanisms of membrane transport in cells, specifically focusing on endocytosis and exocytosis.
-
Endocytosis involves the formation of vesicles or invaginations in the cell membrane, which pinch off into the cytoplasm with the receptor-bound ligands trapped inside. Clathrin molecules form cage-like structures on the cytoplasmic surface of the cell membrane for this process.
-
Another type of endocytosis, called caveolae, involves the interaction of caveolins with cavins. This type of endocytosis is common in thin cells.
-
The produced vesicles are transported to the endosomal compartment, a collection of tubules and vacuoles in the peripheral cytoplasm. The clathrin molecules separate and recycle back to the cell membrane.
-
The trafficking of the endosomal vesicles is regulated by Rab proteins, which bind to guanine nucleotides and associated proteins. Phagosomes and pinocytotic vesicles typically fuse with lysosomes for digestion.
-
Exocytosis is the process of releasing macromolecules from the cell by the fusion of a cytoplasmic vesicle with the plasma membrane. This process can occur via constitutive or regulated secretion.
-
Membrane fusion during exocytosis is highly regulated, with specific interactions between membrane proteins. Membranes are returned to the cell surface after exocytosis in a process called membrane trafficking.
-
Cells communicate with one another by means of gap junctions and receptors. Cells use about 25 families of receptors to detect and respond to various extracellular molecules and physical stimuli, enabling specific and programmed responses.
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During exocytosis, small membrane-bound structures called exosomes may be released, carrying their contents and membranes to other cells as a form of cell-to-cell communication.
-
Membrane transport plays a crucial role in maintaining cellular function and physiological processes. Multivesicular bodies are formed by the invagination of the limiting membrane of vacuoles and tubules, and they can either merge with lysosomes for selective degradation or fuse with the plasma membrane and release the intraluminal vesicles outside the cell.
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Membrane components are continuously trafficked in most cells, and this process is essential for maintaining the cell and for physiological processes.
-
Exocytosis is triggered by a transient increase in cytosolic Ca2+ and is highly regulated, as shown by selective interactions between membrane proteins during membrane fusion.
-
The text also mentions that channels, diffusion, and carrier proteins are used for various types of membrane transport.
-
The plasma membrane is the major site of membrane transport in cells, and it plays a crucial role in maintaining the cell and regulating various physiological processes.
-
Embryonic stem cells are formed when the inner cell mass of a fertilized egg is cultured in laboratory conditions.
-
Most cells undergo differentiation, during which they specialize in specific functions and change shape accordingly.
-
Muscle cells, for example, express proteins like actin, myosin, and proteasomes, which enable them to produce forceful contractions.
-
The cytoplasm of cells contains major organelles such as mitochondria, peroxisomes, microtubules, microfilaments (actin filaments), and intermediate filaments.
-
The plasma membrane is the outermost layer of eukaryotic cells and is composed of phospholipids, cholesterol, and proteins.
-
The plasma membrane acts as a selective barrier, regulating the passage of materials into and out of the cell and facilitating the transport of specific molecules.
-
The plasma membrane is approximately 7.5 to 10 nm thick and contains an outer layer of lipids and proteins, an inner layer of lipids and proteins, and a middle region of cholesterol.
-
Proteins, particularly integrins, allow for continuous exchange of information between the cytoplasm and the extracellular matrix, blurring the line between the interior and exterior of the cell.
-
The plasma membrane's composition includes both integral proteins, which are incorporated into the lipid bilayer, and peripheral proteins, which bind to the lipid bilayer or the cytoplasmic surface.
-
The plasma membrane allows the passage of ions and other molecules through various transport mechanisms: water (aquaporins), small molecules (carriers), and against concentration gradients (membrane pumps).
-
Membrane structure: phospholipid bilayer, proteins, cholesterol, and carbohydrates.
-
Functions of the Plasma Membrane: physical barrier, selective permeability, electrochemical gradients, communication and transport by vesicles.
-
Membrane proteins are involved in various functions, such as receptors and transporters.
-
Endocytosis: a cellular process where substances, like particles or fluids, enter the cell by enclosing them in vesicles.
- Three major types: phagocytosis, pinocytosis, and receptor-mediated endocytosis.
-
Receptor-mediated endocytosis: involves the binding of specific ligands to integral membrane proteins (receptors) which then invaginate and pinch off as vesicles.
-
Intracellular transport of endocytosed materials through the cell: vesicles fuse with lysosomes for degradation or release their contents at the cell surface through transcytosis.
-
Membrane proteins exhibit fluid-like behavior, resulting in lateral movements across the membrane, but some are anchored in place through links to the cytoskeleton.
Test your knowledge of cell membrane proteins with this quiz. Explore the differences between peripheral and integral proteins and understand the role of hydrophobic interactions in protein integration within the lipid bilayer.
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