What percentage of the cell membrane is made up of cholesterol?
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13%.
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What percentage of the cell membrane is made up of cholesterol?
13%.
What type of substances diffuse through lipid membranes?
Lipid soluble substances.
What happens at equilibrium in a diffusion process?
The concentration becomes uniform.
Is the inside of the cell membrane the same as the outside?
No, the inside and outside of the cell membrane have different compositions and properties.
What is the permeability of the membrane to water?
The membrane is permeable to water.
What role do channel proteins play in the cell membrane?
They facilitate the transport of substances across the membrane, often down their concentration gradient.
What is one function of plasma proteins?
Transport.
What is primary active transport?
A process that uses ATP to move ions or molecules against their concentration gradient.
What is the significance of your appreciation?
It acknowledges the effort and understanding in communication.
What is facilitated diffusion?
A process that allows substances to cross membranes with the assistance of special proteins.
What type of molecules cannot easily pass through impermeable membranes?
Ions and hydrophilic molecules.
What characteristic of the membrane affects the passage of ions and hydrophilic molecules?
The hydrophobic nature of the membrane.
How do plasma proteins function as receptors?
They bind to specific molecules to initiate a response.
What role do plasma proteins play as enzymes?
They catalyze biochemical reactions.
What is the primary mechanism for the faster transport of d-glucose across the plasma membrane of adipose cells in the presence of insulin?
Carrier-mediated transport of glucose.
Which type of substances are typically restricted from passing through the lipid bilayer?
Water-soluble substances.
What is diffusion?
The movement of substances from an area of higher concentration to an area of lower concentration.
What condition is associated with autoantibodies blocking Ca2+ channels?
Lambert-Eaton syndrome.
Is the membrane permeable to albumin?
No, the membrane is not permeable to albumin.
What are the two types of proteins found in the cell membrane?
Peripheral proteins and integral proteins.
What is the primary structure of the plasma membrane?
A lipid bilayer.
What is the function of cell recognition proteins?
They help cells identify and communicate with each other.
What is the primary function of the plasma membrane?
To separate the inside from the outside and regulate exchange between them.
What is facilitated diffusion?
The passage of water-soluble solutes and ions through a hydrophilic pathway created by integral proteins.
What contributes to the uniqueness of each individual's cells?
The diversity of carbohydrate chains in the glycocalyx.
What percentage of the cell membrane is composed of carbohydrates?
3%.
How selective are channel and carrier proteins?
Both are highly selective in the types of molecules or ions that are allowed to cross the membrane.
What would happen to the movement of K+ out of a cell if ATP production stopped?
It would cease.
What is the role of ATPases in primary active transport?
They act as pumps to move substances against their concentration gradient.
How does the polarized organization of epithelial cells affect solute movement?
It ensures directional movement of solutes and water across the epithelial layer.
What happens to the other molecule(s) during secondary active transport?
They are dragged from low to high concentration (uphill transport).
What is the function of afferent neurons in a negative feedback system?
They transmit signals to the brain about changes in the environment.
What role do symporters play in secondary active transport?
They transport two different molecules in the same direction across the membrane, using the energy from one molecule's gradient.
What characterizes active transport?
It requires energy to move substances against their concentration gradient.
What is required for active transport?
ATP hydrolysis.
What is the primary building block of cell membranes?
Phospholipids.
What is a glycoprotein?
A protein/sugar moiety.
What is the relationship between simple diffusion and flux?
There is a linear relationship between simple diffusion and flux.
In which direction does facilitated diffusion occur?
From higher concentration side to lower concentration side.
What is Glycosylphosphatidylinositol (GPI)?
A glycolipid that anchors proteins to the cell membrane.
What types of substances typically pass through channel proteins?
Ions and small polar molecules.
How does membrane thickness affect solute permeability?
Thicker membranes generally reduce permeability.
What do the carbohydrate chains of glycolipids and glycoproteins form?
The glycocalyx.
What effect does increasing the thickness of the membrane have on diffusion?
It decreases the rate of diffusion.
What mechanisms do cells use to regulate their volume under osmotic stress?
They may use ion channels, transporters, and osmolytes to adjust their internal solute concentration.
What role does insulin play in the transport of glucose in adipose cells?
It increases the speed of d-glucose transport across the plasma membrane.
What provides the energy for primary active transport?
ATP.
What role does the Na/K+ - ATPase play in glucose transport?
It helps maintain the Na+ gradient necessary for glucose transport.
What must be balanced regarding charges inside and outside the cell?
The number of positive and negative charges.
How do proteins contribute to cell membrane structure?
They are integral and peripheral components that help maintain the membrane's integrity and functionality.
What percentage of the general population has lactose intolerance?
At least 10%.
What is the correct answer to the question regarding transport processes ceasing due to cyanide?
D. All of these options are correct.
What is the significance of protein folding?
Proper folding is essential for protein function and determines how proteins interact with other molecules.
What type of process is diffusion?
Passive process.
What role do antiporters play in secondary active transport?
They transport two different molecules in opposite directions across the membrane, utilizing the energy from one molecule's gradient.
Is glucose transported via receptor-mediated endocytosis?
No, glucose is not transported this way.
What is the role of ion channels in the cell membrane?
To facilitate the movement of ions across the membrane.
What are glycolipids composed of?
Lipid/sugar moiety.
What is an integrin?
An adhesion molecule that attaches the cell to the extracellular matrix.
What is diffusion in the context of dye molecules?
The movement of dye molecules down their concentration gradient.
What is the maximum size of water-soluble substances that can diffuse?
Up to 0.8 nm.
How does facilitated diffusion via uniporters compare to simple diffusion?
Facilitated diffusion via uniporters is faster than simple diffusion but is saturable.
In which direction does diffusion occur?
From higher concentration to lower concentration.
What is inhibited in Lambert-Eaton syndrome due to blocked Ca2+ channels?
Ca2+-dependent exocytosis of vesicles filled with acetylcholine (Ach).
What neurotransmitter is affected in Lambert-Eaton syndrome?
Acetylcholine (Ach), which is needed for muscle contraction.
Which substances can easily pass through the cell membrane?
Oxygen, carbon dioxide, and alcohol.
What is a channel protein?
A type of protein that allows specific ions or molecules to pass through the cell membrane.
What is the result of inhibited exocytosis of Ach in Lambert-Eaton syndrome?
Muscle weakness.
What role do carrier proteins play in facilitated diffusion?
They help transport substances across the cell membrane without using energy.
Which type of molecules can easily pass through impermeable membranes?
Small and hydrophobic molecules.
What is facilitated diffusion?
A process that requires a carrier to transport molecules across a membrane.
What is active transport?
The movement of substances against their concentration gradient using energy.
What factors determine the permeability of a solute across a lipid bilayer membrane?
Molecular radius, oil/water partition coefficient, and membrane thickness.
What is the primary function of GPI in the cell membrane?
To serve as an anchor for proteins.
What is secondary active transport?
A process that uses the energy from the electrochemical gradient created by primary active transport.
Which solute characteristics contribute to higher permeability across a lipid bilayer?
Smaller molecular radius and higher oil/water partition coefficient.
What are glycolipids?
Phospholipids with carbohydrate chains.
What is the thickness range of the cell membrane?
7.5 to 10 nm.
What type of particles can diffuse through carrier proteins in facilitated diffusion?
Larger particles, such as glucose.
What processes allow macromolecules to cross the plasma membrane?
Endocytosis and exocytosis.
What are glycoproteins?
Proteins that have carbohydrate chains attached.
What percentage of the cell membrane is composed of protein?
55%.
What determines the ability of substances to move in and out of the cell?
The lipid bilayer of the plasma membrane.
What is one function of the glycocalyx?
Cell-to-cell recognition.
What happens during passive movement of a solute across a membrane?
It dissipates the gradient and reaches equilibrium, resulting in no net movement of solute.
Which factor increases the rate of diffusion of a particle across a membrane?
C. The area of the membrane increases.
What is the percentage composition of phospholipids in the cell membrane?
25%.
Can you name a function of plasma proteins related to signaling?
Function as receptors.
What type of substances are impermeable to the cell membrane?
Usual water-soluble substances, such as ions and glucose.
What is facilitated diffusion?
The movement of substances across a membrane via carrier molecules.
How many molecules can pass through a carrier at a time during facilitated diffusion?
Only a single molecule.
In which direction do molecules move during facilitated diffusion?
From higher concentration to lower concentration.
What role does the glycocalyx play in cell adhesion?
It facilitates cell-cell adhesion.
What is the significance of transport by plasma proteins?
They help in the movement of substances across the membrane.
What role do cell recognition proteins play in the immune system?
They help the immune system distinguish between self and non-self cells.
What are proteins made of?
Amino acids.
Does secondary active transport directly utilize energy?
No, it depends on primary active transport.
What are the two types of transporters involved in primary active transport?
Uniporter and biporter (symport or antiport).
What is the role of concentration gradient in channel protein function?
It allows the movement of water and selected ions or molecules.
How does the concentration of ions vary across the cell membrane?
It varies widely between the inside and outside of the cell.
What role do effectors play in a negative feedback system?
They carry out the response to restore balance.
What is the primary function of the cell membrane?
To protect the cell and regulate what enters and exits.
What is the main difference between carrier-mediated transport systems and channels?
Carrier-mediated transport involves specific binding and conformational changes, while channels allow passive movement of molecules through a pore.
What are the two main types of membrane transport systems?
Active transport and passive transport.
What energy drives the process of diffusion?
The energy of normal kinetic motion of matter.
Can glucose pass through the cell membrane via simple diffusion?
No, glucose molecules are too large for significant simple diffusion.
How do phospholipids behave in the cell membrane?
They are fluid and mobile.
How does water move across a plasma membrane?
C. simple diffusion through membrane channels.
Are channel proteins involved in active or passive transport?
They are primarily involved in passive transport.
What type of molecules does GPI typically anchor?
Proteins, particularly those involved in signaling.
Which type of substances can easily pass through the lipid bilayer?
Lipid-soluble substances.
What is the main characteristic of primary active transport?
Moves substances against their concentration gradient.
What is the basic structure of the plasma membrane?
A phospholipid bilayer with embedded proteins.
How is facilitated diffusion of small ions mediated?
By specific pores and ion channel proteins.
What is facilitated diffusion?
A process that allows substances to cross membranes with the assistance of special proteins.
What characteristic of a cell membrane increases membrane fluidity?
E. Unsaturated phospholipid content.
What is the role of active transport in solute movement?
It uses metabolic energy to move solutes against gradients, preventing a state of equilibrium.
What is secondary active transport?
A type of transport that uses the energy from the electrochemical gradient created by primary active transport to move substances against their concentration gradient.
What effect do saturated phospholipids have on membrane fluidity?
They decrease membrane fluidity.
What happens to sodium (Na) levels in lactose intolerance?
Sodium (Na) levels increase.
How does the sodium-potassium pump relate to secondary active transport?
It creates the sodium gradient that is used by secondary active transporters to move other substances into the cell.
How do cells regulate their volume?
By moving solutes in or out to drive osmotic entry or exit of water.
What is selective permeability?
The ability of the cell membrane to allow certain substances to pass while blocking others.
What happens to glucose levels when amino acid levels increase?
Glucose levels increase.
How does secondary active transport utilize the Na+ gradient?
The inwardly directed Na+ gradient is used to drive glucose uptake from the intestine.
What do membranes structurally define?
Cells, nucleus, and organelles.
How does secondary active transport differ from primary active transport?
It uses the energy from the movement of one substance down its concentration gradient to drive the movement of another substance against its gradient.
What is simple diffusion?
The passage of lipid-soluble solutes across the plasma membrane through the lipid bilayer.
Which type of glucose is transported faster in adipose cells when insulin is present?
d-glucose.
Which ions are higher in concentration outside the cell?
Na+ (sodium) and Cl- (chloride).
What is the purpose of negative feedback systems in the body?
To maintain homeostasis.
Which glucose type is transported slower across the plasma membrane of adipose cells?
l-glucose.
How does the glycocalyx contribute to cell adhesion?
The glycocalyx of some cells attaches to the glycocalyx of other cells, thus attaching cells to one another.
How does body cold stress affect cell membrane fluidity?
It decreases membrane fluidity.
In secondary active transport, how does one molecule move?
Down its concentration gradient (high to low).
What happens when hormones bind to the glycocalyx?
It activates attached internal proteins that, in turn, activate a cascade of intracellular enzymes.
What role does Ca²⁺ play in neurotransmitter release?
It is essential for the exocytosis of vesicles filled with neurotransmitters.
What is the basic structure of the cell membrane?
A phospholipid bilayer with embedded proteins.
Where does exchange transport of glucose occur?
In the kidneys, but not in adipose tissue.
What happens to sodium (Na) levels when glucose levels increase?
Sodium (Na) levels decrease.
Can a small amount of glucose diffuse across the membrane?
Yes, but it is minimal and requires adequate time.
What is the function of cholesterol in cell membranes?
It stiffens membranes.
What properties of epithelial cells are necessary for directional movement of solutes and water?
Polarity, tight junctions, and specific transport proteins.
What does secondary active transport ultimately depend on?
Primary active transport.
What is the percentage of other lipids in the cell membrane?
4%.
What is Lambert-Eaton syndrome?
A neurologic condition caused by autoantibodies that block Ca²⁺ channels on presynaptic motor nerve terminals.
Would osmosis be affected if ATP production stopped?
No, osmosis is a passive process and does not require ATP.
What are the characteristics of the heads of phospholipids?
They are hydrophilic (water-loving) and polar.
What neurotransmitter's release is inhibited in Lambert-Eaton syndrome?
Acetylcholine.
What types of molecules typically use facilitated diffusion?
Polar molecules and ions that cannot easily cross the lipid bilayer.
What role do proteins play in membrane transport?
They act as channels and carriers to facilitate the movement of substances across the membrane.
What is the role of integral membrane proteins in relation to membrane fluidity?
They do not significantly increase membrane fluidity.
What happens to glucose levels in lactose intolerance?
Glucose levels decrease.
What is facilitated diffusion?
Diffusion that occurs with the help of a carrier protein.
What is the main difference between active and passive transport?
Active transport requires ATP hydrolysis, while passive transport does not.
What is passive transport?
The movement of substances along their concentration gradient without the use of energy.
What role do phospholipids play in cellular signaling?
They provide some substrate for cellular signaling.
What do channel proteins allow to move across the membrane?
Free movement of water as well as selected ions or molecules.
How does the glycocalyx contribute to signal reception?
It helps in the reception of signal molecules.
How are concentration gradients for secondary transport created?
Using energy from ATP.
What happens to the rate of diffusion when the concentration of the particle decreases?
The rate of diffusion decreases.
What is the significance of the cellular 'fingerprint'?
It provides each individual with a unique identification.
What characteristic of the plasma membrane allows for fluidity?
Its fluid consistency.
Which component of the negative feedback system detects changes?
Receptors.
How are voltage-gated channels opened?
By changes in membrane potential.
What is an example of secondary active transport?
The sodium-glucose cotransporter, which uses the sodium gradient to transport glucose into cells.
Where do the hydrophobic tails of phospholipids extend?
To the interior of the membrane.
What is the role of peripheral membrane proteins in relation to membrane fluidity?
They do not significantly affect membrane fluidity.
Are related steroids found in plants?
Yes, related steroids are found in plants.
What are the two main types of membrane transport?
Active transport and passive transport.
What is the difference between primary and secondary active transport?
Primary active transport directly uses ATP, while secondary active transport uses the energy from the electrochemical gradient created by primary transport.
In what way can cholesterol move within the membrane?
It can move in any dimension through the membrane.
Where are cell recognition proteins typically found?
On the surface of cell membranes.
What is the effect of 2,4 dinitrophenol on intestinal epithelial cells?
It results in loss of ATP synthesis.
What would happen to the movement of Na+ out of a cell if ATP production stopped?
It would cease.
What is one function of the glycocalyx related to surface charge?
It provides a negative surface charge that repels other negative objects.
How are molecules assembled to form a selectively permeable barrier in the plasma membrane?
Phospholipids arrange themselves in a bilayer with hydrophilic heads facing outward and hydrophobic tails inward, creating a barrier.
Does facilitated diffusion require energy?
No, it is a passive transport process.
Where do the hydrophilic heads of phospholipids lie?
On the outward-facing and inward-facing surfaces of the membrane.
What is the consequence of the loss of the Na+ gradient in intestinal epithelial cells?
GLUT2 will not be able to transport glucose across the apical membrane.
What role do carrier proteins play in facilitated diffusion?
They help transport specific substances across the cell membrane.
How do carbohydrate moieties of glycocalyx participate in immune responses?
Some carbohydrate moieties enter into immune reactions.
What type of specificity do glucose carriers have?
They are stereo-selective for d-glucose.
What is the driving force for ion transport across the membrane?
The sum of the electrical and chemical gradients, known as the gradient of electrochemical potential.
Can you name a type of passive transport?
Diffusion or facilitated diffusion.
What is secondary active transport?
Transport that couples the movement of two or more solutes together, using the energy from one solute's electrochemical gradient to drive the transport of another.
Why is the maintenance of solutes on both sides of the membrane critical to the cell?
It helps to keep the cell from rupturing.
What type of transport is always considered uphill?
Primary active transport.
What happens during the conformational change in a carrier protein?
It moves the substances through the interstices of the protein to the other side of the membrane.
Which ion is higher in concentration inside the cell?
K+ (potassium).
What component is typically missing at point labeled X in a negative feedback system?
Efferent neurons.
What happens to the SGLT on the apical membrane when ATP synthesis is lost?
It will not be able to transport Na+ out of the cell.
Which transport processes would cease if ATP production stopped?
The movement of Na+ and K+ out of a cell would cease.
What are the characteristics of the tails of phospholipids?
They are hydrophobic (water-fearing) and nonpolar.
What are the two types of diffusion?
Simple diffusion and facilitated diffusion.
What drives water movement across the plasma membrane?
Differences in osmotic pressure.
What role do proteins play in the cell membrane?
They assist in transport, communication, and structural support.
What is passive transport?
The movement of substances across a membrane without the use of energy, following their concentration gradient.
What is primary active transport?
Transport that occurs via membrane proteins directly coupling ATP hydrolysis to solute movement.
What is the arrangement of individual phospholipids in the membrane?
They remain in a single monolayer.
How do carrier proteins transport substances?
By binding with molecules or ions and undergoing conformational changes.
What types of molecules constitute the plasma membrane?
Phospholipids, proteins, cholesterol, and carbohydrates.
What model describes the structure of the plasma membrane?
The fluid-mosaic model.
How do autoantibodies affect Ca²⁺ channels in Lambert-Eaton syndrome?
They bind to and block the channels, inhibiting Ca²⁺-dependent exocytosis.
How many molecules are transported in secondary active transport?
Two or more molecules through a carrier protein.
What role does glycocalyx play in hormone binding?
It acts as a receptor for binding hormones, such as insulin, activating attached internal proteins.
What is diffusion?
Random molecular movement of substances molecule by molecule through intermolecular spaces in the membrane or with the help of proteins.
How are ligand-gated channels opened?
By the binding of specific molecules (ligands) to the channel.
What protein mediates glucose transport across adipose cell membranes?
GLUT4 (the insulin-dependent glucose transporter).
What other lipid is mentioned as being present in animal membranes?
Cholesterol.
What is the relationship between lactose intolerance and amino acid levels?
Amino acid levels decrease in lactose intolerance.
What is active transport?
The movement of substances against their concentration gradient, requiring energy.
What is the significance of the fluid mosaic model?
It describes the dynamic nature of the cell membrane, where lipids and proteins can move laterally.
How does the size of the particle affect its diffusion rate?
Increasing the size of the particle decreases the rate of diffusion.
Why is glucose transport from the apical to basolateral side of intestinal cells reduced after treatment with 2,4 dinitrophenol?
Because the Na+ gradient across the apical membrane will be dissipated.
What can happen if cell recognition proteins malfunction?
It can lead to autoimmune diseases or tissue rejection.
What is the primary function of proteins in the body?
To perform a variety of functions including structural support, transport, and catalysis.
How does the plasma membrane maintain an internal environment that differs from extracellular fluid?
By regulating the transport of ions and molecules through selective permeability.
What pattern do the embedded proteins in the plasma membrane create?
A mosaic pattern.
What is the result of inhibited acetylcholine release in Lambert-Eaton syndrome?
Muscle weakness.
What are aquaporins?
Channel proteins that allow rapid water movement across the plasma membrane.
What is the difference between facilitated diffusion and simple diffusion?
Facilitated diffusion requires specific transport proteins, while simple diffusion does not.
What happens to amino acid levels in lactose intolerance?
Amino acid levels decrease.
Where does primary active transport of glucose occur?
In the gut, but not in adipose tissue.
What is the role of carrier proteins in membrane transport?
They assist in the movement of substances across the membrane, either actively or passively.
What characterizes passive transport?
It does not require ATP hydrolysis or coupling to another solute.
