Unit III Flashcards
What are the functions of cell membrane
Controls what enters and exits the cell to maintain an internal balance
Provides protection and support for the cell
The internal balance inside the cell that cell membrane maintains is called
Homeostasis
Some membrane contains proteins called
Membrane proteins
The phosphate head of the cell membrane is ________, and the fatty acid tails is __________.
Polar, non-polar
Allows a molecules in and keeps other molecules out
Selectively permeable
In 1972 they proposed that the membrane is a mosaic of proteins dispersed within the bilayer with only the hydrophilic regions exposed to water.
S.J Singer and G. Nicolson
70% of cell membrane proteins part and parcel of membrane structure
Integral proteins
Lei transfer substances against concentration/ electrical gradient
Pumps
Opened and closed by gates
Channel proteins
It involved in transport of substances
Carrier proteins
It takes place in membrane reaction
Enzyme proteins
They bear appropriate sites for recognition of specific ligands
Receptor proteins
They are bound to the surface of the membrane
Peripheral proteins
Other functions of cell membrane
Transport
Enzymatic activity
Signal transduction
Cell to cell recognition
Intercellular joining
Attachment to the cytoskeleton and extracellular matrix (ECM)
Carbohydrates covalently bonded to lipids
Glycolipids
Membrane carbohydrates covalently bonded to proteins
Glycoproteins
__________ molecules such as hydrocarbons can dissolve in the lipid bilayer and passed through the membrane rapidly
Hydrophobic or nonpolar molecules
__________ molecule such as sugars do not cross the membrane easily
Polar molecules
It allows passage of hydrophilic substances across the membrane
Transport proteins
Transport proteins that have hydrophilic channel that certain molecules or ions can use as a tunnel
Channel protein
Channel proteins that facilitate the passage of water
Aquaporins
Transport proteins that bind to molecules and change shape to shuttle them across the membrane
Carrier proteins
Two types of transport mechanism
Active transport
Passive transport
What are the two types of active transport
Primary transport
Secondary transport
What are the four types of passive transport
Simple diffusion
Facilitated diffusion
Osmosis
Bulk flow filtration
The tendency for molecules spread out evenly into the available space
Diffusion
The region along which the density of a chemical substance increase or decrease
Concentration gradient
The diffusion of a substance across a biological membrane that uses no energy to make it happened
Passive transport
What are the factors that influence diffusion rates
Distance
Molecular size
Temperature
Steepness of concentration gradient
Membrane of surface area
Two types of diffusion across membranes
Simple diffusion
Channel mediated diffusion
Lipophilic substances can enter cells easily because they diffuse through the lipid portion of the membrane
Simple diffusion
It is used by irons very small water-soluble compounds. Much more complex than simple diffusion.
Channel mediated diffusion
The diffusion of water across a selectively permeable membrane
Osmosis
The ability of a surrounding solution to cost a cell to gain or lose water
Tonicity
It is a solution are solute concentration is the same as the inside of the cell. No net water movement across the plasma membrane has happened
Isotonic solution
A solution where solute concentration is greater than that inside the cell where the cell loses water
Hypertonic solution
A solution are solute concentration is less than that inside the cell where the cell gains water
Hypotonic solution
In a hypotonic solution animal cells become ________, while plant cells become _________.
Lysed, Turgid (normal)
In a isotonic solution animal cells become ___________, while plant cells become _________.
Normal, Flaccid
In a hypertonic solution animal cells become _________, while plant cells become ___________.
Shriveled, Plasmolyzed
It uses energy to move solutes against their gradients
Active transport
Give one type of active transport system
Sodium-potassium pump
It is the fault age difference across a membrane
Membrane potential
To combined forces that drive the diffusion of ions across a membrane
Electrochemical gradient
The effect of the membrane potential on the ions movement
Electrical force
It is a transport protein that generates voltage across a membrane
Electrogenic pump
It is the main electrogenic pump of plants, fungi, and bacteria
Proton pump
It is a couple transport by a membrane protein
Cotransport
It occurs when active transport of a solute in directly drives transport of other solutes.
Cotransport
It occurs by exocytosis and endocytosis. It requires energy
Bulk transport
Large molecules such as polysaccharides and proteins cross the membrane in the bulk via
Vesicles
Transport vesicles migrate to the membrane, fused with it, and realistic intense. Many secretory cells use this to export their products
Exocytosis
The cell takes in macromolecules by forming vesicles from the plasma membrane. It is the reversal of exocytosis.
Endocytosis
What are the three types of endocytosis
Phagocytosis
Pinocytosis
Receptor mediated endocytosis
It is also called as cellular eating
Phagocytosis
Pinocytosis is also called as
Cellular drinking
