Chapter 4 Flashcards
What is the phospholipid bilayer?
Contains hydrophilic (water loving) heads that face the inside and outside of the cell, and hydrophobic (water fearing) tails that face each other, away from the water
What are the membrane proteins that are throughout the membrane?
Peripheral proteins which are associated with only one side of the membrane, Integral proteins which span the membrane and can protrude from one or both sides.
What are glycolipids?
Lipids that are attached to carbohydrates and provide energy to the cell and aid in cell to cell communication.
What are glycoproteins?
Cell recognition proteins that are attached to carbohydrates and can recognize when it is being invaded by pathogens and try to block. The carbohydrates help protein maintain proper shape and solubility.
What are channel proteins and what do they do?
They are involved in the passage of solutes through the membrane and they may have a gate that opens in response to a signal. (Mostly for smaller molecules)
what are cell recognition proteins?
The major histocompatibility complex glycoproteins are different for each person, so organ implants are difficult to achieve.
What are receptor proteins?
They are shaped in a way that a specific molecule can bind to it.
What is an enzymatic protein?
It catalyzes a specific reaction, and the membrane protein adenylate cyclase is involved in ATP metabolism.
Describe the permeability of the plasma membrane.
It is selectively permeable for molecules that are small in size, and have no polarity or charge.
What is a concentration gradient?
Move of a substance on one side of the membrane. Can go down naturally from an area of higher to lower concentration or up unnaturally from an area of lower to higher concentration.
What are aquaporins?
Special channels that allow water to cross the membrane and are present in the majority of cells.
How do large molecules cross the membrane?
Channel proteins, carrier proteins, and vesicle formation.
Explain diffusion
Energy is not required as it happens naturally, it moves down a concentration gradient, and requires a concentration gradient, and it occurs until equilibrium is reached.
Explain facilitated transport
Energy is not required, it moves down a concentration gradient, and requires a channel and carrier protein as well as a concentration gradient.
Explain active transport
Energy is required, it moves up a concentration gradient, and it requires a carrier as well as energy (usually ATP). The molecules or ions combine with carrier proteins often called pumps.
Explain exocytosis
Energy is required, it moves towards the outside, and requires a vesicle to fuse with the plasma membrane
Explain Endocytosis
Energy is requires, it moves towards the inside, and requires vesicle formation
What factors influence the rate of diffusion
Temperature, electrical currents, molecule size.
What is osmosis
The diffusion of water across a differentially permeable membrane, 3 kinds: Hypotonic, Hypertonic, and Isotonic
Describe Hypotonic solutions
A solution that has a lower solute concentration than the inside of the cell, the cell gains water. (Turgor pressure)
Describe Isotonic solutions
Solute concentration is equal inside and outside the cell, there is no movement
Describe Hypertonic solutions
A solution has a higher concentration than the inside of the cell, and the cell loses water. (Lyse)
What is a sodium-potassium pump?
For muscle and nerve cells to work, Na+ is pumped out and K+ is pumped in. Since there is already a greater K+ concentration in the cell, goes up/across gradient. ATP is needed.
What is bulk transport?
Macromolecules are transported in/out of cells by vesicle formation
What is endocytosis
Cells take in substances by vesicle formation, part of the plasma membrane folds to envelope the substance and the membrane pinches off to form an intracellular vesicle. 3 types: Phagocytosis, pinocytosis, and receptor-mediated endocytosis
Describe Phagocytosis
Larger, particular matter such as viruses and whole cells
Describe pinocytosis
Liquids and small particles dissolved in a liquid like certain blood cells or plant root cells
Describe receptor mediated endocytosis
A type of pinocytosis that involves a coated pit like specific placental cells.
What are the 2 types of cell surfaces animal cells have
Extracellular matrix on the outside of the cell, and junctions that occur in between the cells.
Describe the extracellular matrix
A meshwork of proteins and polysaccharides closely associated with cells that produced them, like a gel that surrounds cells. Polysaccharides made of amino sugars in ECM attach to proteins called proteoglycans which reach into the ECM but can attach to cell membrane.
Describe the junctions between cells
Cell surfaces in certain tissues of animals.
What are the different types of junctions and describe them.
Adhesion junctions: intercellular filaments between cells, cytoskeleton filaments maintain a short distance between cells, prominent with skin cells.
Tight junctions: proteins usually connect through plasma membranes together. “zipper like”
Gap junctions: plasma membrane channels are joined between cells so the cells can then communicate.
