Chapter 5: Membrane Structure, Synthesis, and Transport Assignment
Processes that are coupled across cell membranes.
-the export of Na+ ions -the import at K+ ions
Moving a solute from areas of low concentration to high concentration requires:
An input of energy
Why is the phospholipid bilayer an effective barrier to hydrophilic or polar molecules?
Because of the hydrophobic interior of the bilayer
Glycosylation is the process of covalently attaching a(n) ____ to a protein or a lipid.
Carbohydrate
What type of proteins form an open passageway for facilitated diffusion of ions or molecules across the membrane?
Channels
Which proteins assist in the movement of molecules and ions across membranes.
Channels / Transporter
Proteins that assist in the movement of substances across membranes can be classified into two types based on how they move solutes across a membrane: _____ and _____
Channels / Transporters
A transmembrane protein destined for the plasma membrane will first be inserted into the:
ER Membrane
Moving a solute against its chemical or electrochemical gradient requires a source of _____
Energy
What property of biological membranes describes the ability of individual molecules to move within the membrane?
Fluidity
A solution in which the solute concentration on both sides of the membrane is equal is classified as
Isotonic
In the 1940s, studies of animal cells suggested that the import of ______ is coupled to the export of ______.
K+; Na+
Lipid tails are inserted into the hydrophobic portion of the membrane.
Lipid-anchored protein
The plasma _____ separates the internal contents of a cell from the extracellular environment.
Membrane
Not covalently bound to membrane
Peripheral membrane protein
The three main types of macromolecules that comprise the plasma membrane are?
Phospolipids Proteins Carbohydrate
What separates the internal contents of a cell from the extracellular environment?
Plasma Membrane
Why do shorter tails make membranes more fluid?
Shorter tails interact less with each other.
Regions inserted into the hydrophobic interior are usually α helices.
Transmembrane protein
What is the basic structure of the plasma membrane?
a phospholipid bilayer
When the concentration of a solute is higher on one side of membrane than the other, a(n) ______ gradient is established.
concentration
Transporter proteins bind their solutes in a hydrophilic pocket and then undergo a(n) ______ change that switches the exposure of the pocket from one side of the membrane to the other.
conformational
Vesicular movement of large molecules into cells is called ____ , and vesicular movement of large molecules out of cells is called ____ .
endocytosis exocytosis
Most membrane components of a eukaryotic cell are synthesized at the:
endoplasmic reticulum
When they are synthesized, transmembrane proteins are first inserted into the ______ membrane before being transferred via vesicles to other regions of the cell.
endoplasmic reticulum
Channel proteins are transmembrane proteins that are used for
facilitated diffusion.
The process of covalently attaching a carbohydrate to a lipid or protein is known as:
glycosylation
Phospholipid bilayers are an effective barrier to many charged or polar solutes because of their ____ interior region.
hydrophobic
When the concentration of solutes on both sides of the plasma membrane are equal, the two solutions are said to be _____
isotonic
The Frye and Edidin experiment showed that
lateral protein movements within the membrane are temperature dependent.
Most phospholipids move freely within a semifluid membrane
laterally along the plane of the membrane in two dimensions
The smooth endoplasmic reticulum is where most eukaryotic membrane _____ are synthesized.
lipid
Lipids with shorter tails contribute to ___ plasma membrane fluidity.
more
The plasma membrane consists of a(n) ____ bilayer.
phospholipid
What are the three molecular components of cellular membranes?
proteins / phsopholipds / carbohydrates
All cells are surrounded by a ____ permeable plasma membrane, meaning that the membrane allows the passage of some molecules and ions but not others
selectively
The plasma membrane of a cell is considered to be
selectively permeable.
The Frye and Edidin experiment demonstrated that lateral protein movement within the membrane is affected by____
temperature
The primary difference between endocytosis and exocytosis is
the direction of transport.
A term that describes a situation in which the concentration of a solute is higher on one side of a membrane than the other is _____
transmembrane gradient.
