Membrane Structure and Function Flashcards
What is the primary function of the plasma membrane?
To regulate the entry and exit of substances in and out of the cell.
True or False: The plasma membrane is impermeable to all substances.
False
Fill in the blank: The plasma membrane is primarily composed of __________ and proteins.
phospholipids
What model describes the structure of the plasma membrane?
Fluid mosaic model
Which component of the plasma membrane helps to stabilize its structure?
Cholesterol
What is the role of membrane proteins?
To facilitate transport, act as receptors, and provide structural support.
True or False: Only small nonpolar molecules can freely diffuse through the plasma membrane.
True
What type of transport does not require energy?
Passive transport
Name one example of passive transport.
Diffusion or osmosis
What is facilitated diffusion?
The process of transporting substances across a membrane with the help of transport proteins.
What is the difference between active transport and passive transport?
Active transport requires energy, while passive transport does not.
Which process involves the engulfing of large particles by the cell membrane?
Endocytosis
Fill in the blank: The process of expelling materials from the cell is called __________.
exocytosis
What is osmosis?
The diffusion of water across a selectively permeable membrane.
True or False: Hypertonic solutions cause cells to swell.
False
In which direction does water move in a hypotonic solution?
Into the cell
What is a concentration gradient?
A difference in the concentration of a substance across a space.
What type of solution has the same concentration of solutes as the cell?
Isotonic solution
What are glycoproteins?
Proteins with carbohydrate chains attached that play a role in cell recognition.
What is the role of receptor proteins in the membrane?
To bind signaling molecules and initiate cellular responses.
True or False: The phospholipid bilayer is hydrophobic on both sides.
False
What is the significance of the fluid nature of the plasma membrane?
It allows for the movement of proteins and lipids within the membrane.
What is endocytosis used for?
To take in large molecules or particles into the cell.
Fill in the blank: The sodium-potassium pump is an example of __________ transport.
active
What happens to a cell placed in a hypertonic solution?
It shrinks or crenates.
What is the primary role of cholesterol in the plasma membrane?
To maintain membrane fluidity.
True or False: Membrane potential is created by differences in ion concentration across the membrane.
True
What are integral proteins?
Proteins that penetrate the hydrophobic core of the lipid bilayer.
What is the main purpose of the plasma membrane’s selective permeability?
To allow essential nutrients in while keeping harmful substances out.
Which type of transport uses vesicles to move materials?
Bulk transport
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration.
What role do aquaporins play in the cell membrane?
They facilitate the transport of water molecules.
What is a glycolipid?
A membrane lipid that is bound to a carbohydrate
What is a glycoprotein?
A membrane component that comprises a sugar OR a carbohydrate bound to an amino acid
What is membrane asymmetry?
Asymmetry of the proteins and other components of one half of the lipid bilayer compared to the other layer
What do phospholipid bilayers depend on?
Density, composition of lipid molecules such as saturated and unsaturated, and temperature as it remains mostly fluid but can become a gel consistency if cold enough
What is a sterol?
A steroid that comprises an OH group and a non-polar, hydrophobic hydrocarbon chain. It regulates biological processes and provides structure. Found in animal cells to stabilize fluidity
What are the roles of membrane proteins?
Structure determines function
Transport - hydrophilic protein channel and shape shifting proteins
Enzymatic active?
Some membrane proteins are associated with photosynthesis and respiration are enzymes
Triggering signals?
Binding of a specific chemical hormone changing membranes
Attachment and recognition?
Proteins will attach to the inner and outer membrane acting as a site for cytoskeleton elements and cell-to-cell communication
What are the six major functions of membrane proteins?
- Transport
- Enzymatic activity
- Signal transduction
- Cell-to-cell communication
- Intercellular joining
- Attachment to cytoskeleton (ECM)
What is an integral membrane protein?
A protein that is embedded in the phospholipid bilayer compared
What is the peripheral membrane protein?
A protein that is on the surface of the membrane held by non-covalent bond
What do cells and organelles have to do when transporting across membranes?
Must be able to take in nutrients, expel waste, and communicate with the environment and surrounding cells
What is passive transport?
Transportation of a substance across a membrane without the use of energy
What is simple diffusion?
The ability of small substances and molecules to pass through a membrane unassisted due to the difference in concentration
What is facilitated diffusion?
Facilitated transport of ions and polar molecules through a membrane via protein complexes. This process is carried out by two transport proteins, channel proteins, and Carter proteins. Diffusion stops when homeostasis is reached.
What is a channel protein?
Some channel proteins form hydrophilic pathways for water and other ions and other protein facilitate the transport of ions (Na, K, C, Cl)
What do carrier proteins do?
They bind to specific solutes such as glucose to transport across the lipid bilayer compared
What is osmosis?
The diffusion of water from a low concentration to a higher concentration
What is hypotonic?
Has a lower concentration than another solution
What is hypertonic?
Has a higher concentration than another solution
What is isotonic?
Has the same concentration
What is active membrane transport?
The movement of substance across membranes against their concentration gradient using pumps
What is primary active transport?
A type of activity where a pump moves positively charged ions against a concentration gradient through a membrane using ATP energy
ATP breaks down into a phosphate group and ADP where the phosphate group will attach to the transporter pump in the membrane creating a high energy state and change the binding sit to fit the ion. The ion attaches to the bonding site and causes the transporter to change shape to create a passage to the area of higher concentration. The phosphate groups and ions are released and the transporter reverts back to its original shape. This is called an electromagnetic gradient
Electrochemical gradient?
A form of stored potential energy caused by the difference in concentration of the ions
What is secondary active transport?
The use of concentration gradient of an ion that was established by the primary active pump as its energy source
What is symport?
A solute moves through the membrane channel in the same direction as the driving ion
What is antiport?
The driving ion moves throughout the membrane channel to provide energy for active transport of another molecule in the opposite direction
What is endocytosis?
Uses energy to fold the cell membrane around extra cellular fluid to create a vessel containing proteins and substances
What is pinocytosis?
When extra cellular fluid, water, and materials is engulfed into the molecule
What is receptor mediated?
When protein receptors along the surface of the membrane will attach to specific molecules and substances and fold to create a coated vessel
What is phagocytosis?
When solid particles, bacteria’s, glucose, etc. is taken in
What is exocytosis?
The exporting of waste and secretory proteins from the cytosol to the membrane exterior of the cell. This is done by al, eukaryotic cells
