Podcast
Questions and Answers
What is the main structure of the cell membrane?
What is the main structure of the cell membrane?
Which component of the cell membrane is responsible for determining its fluidity and elasticity?
Which component of the cell membrane is responsible for determining its fluidity and elasticity?
Which type of phospholipid is exclusively found in the inner leaflet of the cell membrane?
Which type of phospholipid is exclusively found in the inner leaflet of the cell membrane?
What structure is formed when carbohydrates attach to lipids on the outer surface of the membrane?
What structure is formed when carbohydrates attach to lipids on the outer surface of the membrane?
Signup and view all the answers
What is NOT a function of membrane proteins?
What is NOT a function of membrane proteins?
Signup and view all the answers
Which type of membrane protein plays a role in cell recognition?
Which type of membrane protein plays a role in cell recognition?
Signup and view all the answers
Which part of the phospholipid molecule is hydrophilic?
Which part of the phospholipid molecule is hydrophilic?
Signup and view all the answers
What role does the glycocalyx layer play on the cell membrane?
What role does the glycocalyx layer play on the cell membrane?
Signup and view all the answers
Which type of molecules can diffuse freely through the lipid bilayer?
Which type of molecules can diffuse freely through the lipid bilayer?
Signup and view all the answers
What effect does increasing temperature have on membrane permeability?
What effect does increasing temperature have on membrane permeability?
Signup and view all the answers
Which of the following factors decreases membrane permeability?
Which of the following factors decreases membrane permeability?
Signup and view all the answers
What is the reason water can pass through the membrane only in limited amounts?
What is the reason water can pass through the membrane only in limited amounts?
Signup and view all the answers
Which of the following molecules cannot pass through the lipid bilayer?
Which of the following molecules cannot pass through the lipid bilayer?
Signup and view all the answers
Which type of fatty acids increases membrane fluidity?
Which type of fatty acids increases membrane fluidity?
Signup and view all the answers
What happens to permeability when the membrane is composed of tightly packed lipids?
What happens to permeability when the membrane is composed of tightly packed lipids?
Signup and view all the answers
What can increase the rigidity of the membrane?
What can increase the rigidity of the membrane?
Signup and view all the answers
What type of molecules face resistance when passing through the membrane?
What type of molecules face resistance when passing through the membrane?
Signup and view all the answers
Which process involves the movement of molecules from an area of high concentration to low concentration without energy?
Which process involves the movement of molecules from an area of high concentration to low concentration without energy?
Signup and view all the answers
What factor does NOT affect the rate of simple diffusion?
What factor does NOT affect the rate of simple diffusion?
Signup and view all the answers
Which of the following substances would most likely pass through the lipid bilayer by simple diffusion?
Which of the following substances would most likely pass through the lipid bilayer by simple diffusion?
Signup and view all the answers
What would increase the rate of facilitated diffusion?
What would increase the rate of facilitated diffusion?
Signup and view all the answers
What is Vmax in the context of facilitated diffusion?
What is Vmax in the context of facilitated diffusion?
Signup and view all the answers
Which type of molecules have greater permeability across the membrane?
Which type of molecules have greater permeability across the membrane?
Signup and view all the answers
How do larger molecules typically pass through the cell membrane?
How do larger molecules typically pass through the cell membrane?
Signup and view all the answers
What occurs when all carrier proteins are fully saturated?
What occurs when all carrier proteins are fully saturated?
Signup and view all the answers
What does Vmax represent in the context of facilitated diffusion?
What does Vmax represent in the context of facilitated diffusion?
Signup and view all the answers
How does a low Km value affect a carrier protein's function?
How does a low Km value affect a carrier protein's function?
Signup and view all the answers
What is the primary function of the sodium-potassium pump?
What is the primary function of the sodium-potassium pump?
Signup and view all the answers
Which type of transport requires energy in the form of ATP?
Which type of transport requires energy in the form of ATP?
Signup and view all the answers
What characterizes osmosis in biological systems?
What characterizes osmosis in biological systems?
Signup and view all the answers
What is the primary means of transport in facilitated diffusion?
What is the primary means of transport in facilitated diffusion?
Signup and view all the answers
What happens to the transport rate when all carrier proteins are saturated?
What happens to the transport rate when all carrier proteins are saturated?
Signup and view all the answers
Which statement about primary active transport is true?
Which statement about primary active transport is true?
Signup and view all the answers
What characterizes secondary active transport?
What characterizes secondary active transport?
Signup and view all the answers
How many sodium ions does the Na-K pump transport out of the cell per cycle?
How many sodium ions does the Na-K pump transport out of the cell per cycle?
Signup and view all the answers
Which of these is an example of primary active transport?
Which of these is an example of primary active transport?
Signup and view all the answers
Which process involves the cell engulfing large particles?
Which process involves the cell engulfing large particles?
Signup and view all the answers
What happens to sodium ions during the action of the sodium-calcium exchanger?
What happens to sodium ions during the action of the sodium-calcium exchanger?
Signup and view all the answers
In what way does the Na-K pump impact cell volume?
In what way does the Na-K pump impact cell volume?
Signup and view all the answers
What is the primary function of phagocytosis?
What is the primary function of phagocytosis?
Signup and view all the answers
Which type of endocytosis is best suited for nutrient uptake?
Which type of endocytosis is best suited for nutrient uptake?
Signup and view all the answers
What differentiates clathrin-mediated endocytosis from caveolin-mediated endocytosis?
What differentiates clathrin-mediated endocytosis from caveolin-mediated endocytosis?
Signup and view all the answers
Which statement about exocytosis is correct?
Which statement about exocytosis is correct?
Signup and view all the answers
What is the main purpose of pinocytosis in immune cells?
What is the main purpose of pinocytosis in immune cells?
Signup and view all the answers
How does energy requirement differ among phagocytosis, clathrin-mediated endocytosis, and caveolin-mediated endocytosis?
How does energy requirement differ among phagocytosis, clathrin-mediated endocytosis, and caveolin-mediated endocytosis?
Signup and view all the answers
Which of the following substances are specifically expelled during exocytosis?
Which of the following substances are specifically expelled during exocytosis?
Signup and view all the answers
What is the main difference between phagocytosis and pinocytosis?
What is the main difference between phagocytosis and pinocytosis?
Signup and view all the answers
Study Notes
Cell Membrane and Transport
- The cell membrane is the outer layer of the cell, selectively permeable.
- The cell membrane structure is described as a fluid-mosaic model.
- The cell membrane is 7.5-10 nanometers thick.
- It contains 55% protein, 25% phospholipids, 13% cholesterol, 4% other lipids, and 3% carbohydrate.
- The main component is a double-layered lipid bilayer.
Membrane Lipids
- The lipid bilayer is made of phospholipid molecules.
- The head of phospholipids are hydrophilic (water-loving), phosphate-containing.
- The tails of phospholipids are hydrophobic (water-fearing), fatty acid-based.
- Hydrophobic tails are positioned inside the bilayer.
- Cholesterol is also present in the membrane, acting as a dissolved form.
- Cholesterol impacts membrane fluidity and elasticity. Increasing cholesterol makes the membrane more rigid.
Membrane Proteins
- Two types exist: integral (spanning the membrane) and peripheral (on one side).
- Integral proteins perform various roles, including transport, recognition, receptors and enzymes.
- Some integral proteins form channels or carriers for molecule transport.
- Peripheral proteins are involved in cell communication, connections to a cytoskeleton or extracellular matrix, and recognition.
Membrane Carbohydrates
- Found only on the outer surface of the cell membrane.
- Attaching carbohydrates to proteins forms glycoproteins.
- Attaching carbohydrates to lipids forms glycolipids.
- The combination of glycolipids and glycoproteins forms the glycocalyx (cell coat).
- The glycocalyx has functions like providing a negative charge. promoting cell-to-cell adhesion and recognizing foreign substances.
Membrane Permeability
- Factors affect membrane permeability.
- Small, nonpolar, fat-soluble molecules easily pass through the lipid bilayer (e.g., oxygen, carbon dioxide, fat-soluble vitamins).
- Water can pass through the bilayer in limited amounts, often through aquaporins.
- Charged particles (ions) cannot pass directly through the hydrophobic core.
- Large, polar molecules (e.g., glucose, amino acids) need transport proteins to cross the membrane.
Membrane Transport
- Substances move across the membrane based on their size, concentration, and solubility.
- Small substances can move through the membrane actively (requiring energy) or passively (no energy).
- Large substances are transported in or out of the cell through endocytosis or exocytosis.
Passive Transport
- Passive transport is a movement of substances across a cell membrane without energy input.
- It involves a concentration gradient; substances move from high concentration to low.
- Three types: simple diffusion, facilitated diffusion and osmosis.
- Simple diffusion involves small, nonpolar molecules passing directly through lipid bilayer.
- Facilitated diffusion uses specialized membrane proteins to transport larger molecules.
- Osmosis is the movement of water across a semipermeable membrane, from low to high solute concentration.
Facilitated Diffusion
- Molecules move across the membrane with specific carrier or channel proteins.
- Facilitated diffusion uses membrane proteins and does not need ATP unlike active transport.
- The speed of this transport is Vmax, which is also affected by the quantity of membrane proteins.
Active Transport
- Active transport moves molecules against their concentration gradient, from low to high, which requires energy.
- Two types: primary (directly uses ATP) and secondary (indirectly uses ATP).
Primary Active Transport
- Directly uses ATP to move ions or molecules against their concentration gradient.
- Examples include sodium-potassium pump, calcium pump, and proton pump.
Secondary Active Transport
- Uses the ion gradient established by primary active transport to move other molecules against their concentration gradient.
- Examples include sodium-glucose transporter (SGLT).
- The sodium is transported down the concentration gradient (from high to low) and drives other molecules across the gradient (e.g. glucose) from low to high concentration.
Endocytosis
- Cells take in large molecules or liquids from the outside by folding its membrane inward.
- Three main types of endocytosis include phagocytosis (bulk uptake of solid particles), pinocytosis (bulk uptake of fluids), and receptor-mediated endocytosis (engulfing specific molecules).
Exocytosis
- The process of expelling substances outside the cell.
- Substance are transported out of the cell by packaging it in vesicles that fuse with the plasma membrane.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on the cell membrane's structure and function, including the fluid-mosaic model and the role of various lipids and proteins. This quiz covers essential concepts of membrane transport and composition that are crucial for understanding cell biology.
