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Ch. 7 Membrane Structure and Function Dynamic
Terms in this set (45)
When a plasma membrane allows some substances to cross it more easily than others.
The boundary that separates a living cell from its surroundings and controls traffic into and out of the cell it surrounds.
what are the two staple ingredients of membranes?
lipids and protiens
-phospholipid is an example
-it has both a hydrophilic region and a hydrophobic region
-most membrane lipids are this
fluid mosaic model
the membrane is a mosaic of protein molecules bobbing in fluid bilayer of phospholipids
what is a membrane held together by mostly?
hydrophobic interactions, which are much weaker than covalent bonds
integral proteins are embedded where?
in the lipid bilayer
peripheral proteins are attached where?
the membrane surface
what are the functions of membrane proteins?
transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to the cytoskeleton and extracellular matrix
Where are membrane proteins and lipids synthesized and modified?
-in the ER
-in the Er and Golgi apparatus
- the inside and outside faces of membranes differ in molecular composition
What does selective permeability of the plasma membrane control?
the exchange of molecules and ions with its surroundings
what do polar molecules and ions require to cross the membrane that hydrophobic substances don't require?
specific transport proteins
The spontaneous movement of a substance down its concentration gradient
when water diffuses out through the permeable membrane of a cell
when the solution outside of a permeable membrane has a higher solute concentration than the cytosol
when the solution outside the permeable membrane has a lower solute concentration
equal solute concentration on the inside and outside of membrane and solution...therefore no osmosis occurs
adaptations in cell walls of cells that lack them
passive transport/ facilitated diffusion
where a transport protein speeds the movement of water or a solute across a membrane down its concentration gradient
faciliate the diffusion of ions across the membrane, here carrier proteins can undergo changes in shape
-uses energy, usually ATP, to move solutes against their gradients
- an example = sodium- potassium pump
What are the two gradients that ions can have?
concentration (chemical) and electrical (voltage)
what does the electrochemical gradient determine?
the net direction of ionic diffusion
what do electrogenic and protein pumps do?
transport proteins that cotribute to electro chemical gradients
cotransport of tow molecules occurs?
when a membrane protein enable the down hill diffusion of one solute to drive the uphill transport of the other
how does bulk transport across the plasma membrane occur?
by exocytosis and endocytosis
what happens in exocytosis?
transport vesicles migrate to the plasma membrane, fuse with it, and release their contents
what happens in endocytosis?
molecules enter cells within vesicles that pinch inward from the plasma membrane
what are the three types of endocytosis?
phagocytosis, pinocytosis, receptor-mediated endocytosis
Why is energy required for active transport?
because it moves solutes against their concentration gradient
All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________.
membrane potential, elecrogenetic bumps
Red blood cells contain approximately a 2% concentration of solutes. A red blood cell is placed into a solution that contains a 4% concentration of solutes to which the cell is not permeable. What will happen to the red blood cell?
The cell will decrease in size as water flows out of it.
Which of the following molecules are most abundant in the plasma membrane?
A phospholipid is an amphipathic molecule, meaning that it has both a hydrophilic region and a hydrophobic region.
Which of the following is correct regarding integral proteins?
These proteins exhibit both hydrophilic and hydrophobic properties.
Peripheral proteins are found on the surface of the plasma membrane.
Integral proteins exhibit both hydrophilic and hydrophobic properties.
Integral proteins carry out a variety of functions in the plasma membrane.
Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?
Membrane carbohydrates function primarily in cell-cell recognition.
In facilitated diffusion, __________ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and __________ proteins allow passage of substances through the plasma membrane after undergoing a subtle change in shape.
role of phospholipids in the structure and function of biological membranes?
they form selectively permeable structure
Which of these statements describes some aspect of facilitated diffusion?
Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.
Which of the following cell structures exhibits selective permeability between a cell and its external environment?
Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane?
exocytosis and smooth and rough ER
A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process?
Which of the following is a correct difference between active transport and facilitated diffusion?
Which of the following plant cells would exhibit the most turgor pressure?
A cell placed in a hypotonic solution
Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability?
Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein?
A nonpolar molecule, such as a hydrocarbon
What are the cartilage rings of the trachea shaped like?
What are the allosteric activators of PFK1?
What is the most common cause and 2nd most common cause of pancreatitis?
What are the primary extracellular ions?
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