Ch. 5
Which of these is hydrophobic like the interior of the plasma membrane?
A
Active transport proteins are also called "pumps," such as hydrogen ion pumps. Identify the reason that these pumps require an input of energy to work.
Active transport proteins require an input of energy because they are moving substances such as ions against their concentration gradient.
What is one feature all receptor proteins must share?
All receptor proteins must span the cell membrane, having a portion outside the cell and a portion inside.
Cell A has no membrane proteins at all. Cell B has aquaporin membrane proteins. Both cells are placed in a hypertonic solution. What will happen?
Cell B shrivels faster than cell A.
On a hot summer day, when a person is sweating a great deal, it is recommended that the person should not hydrate with soda or caffeinated beverages. Applying the principles of osmosis, why would drinking such beverages lead a person to become more dehydrated?
Drinks heavy with sugar or caffeine will be hypertonic to the body's cells and cause water to move out of the cells promoting further dehydration.
Patients with cystic fibrosis have a variety of symptoms, including congestion in the lungs from thick mucus, liver blockage by thickened bile, and excessively salty sweat. Based on these symptoms, what would you guess to be the cause of cystic fibrosis?
Failure of an ion transporter causes salt imbalances. This causes problems with osmosis.
_____ aid in the coordination of the activities of adjacent animal cells.
Gap (communicating) junctions
Vibrio cholerae causes severe diarrhea in its victims. How might it cause this to occur?
It tricks the cells of the intestines into secreting ions.
Cells are rarely large enough to be visible due to restrictions of area and volume. Neuron cells reach lengths of up to several feet; they can be very long and thin. How will this affect their surface area and their ability to interact with their environment within the context of the body?
Neurons have more surface area than spherical cells because they are long and thin.
Which of these statements is TRUE with regard to this animation
Sodium and potassium ions are transported against their concentration gradients
If a patient were to receive an intravenous solution that was hypertonic compared to the patient's blood, which of the following would most likely occur?
The blood cells would lose water, as the net movement of water molecules tries to achieve equilibrium. The patient could be severely dehydrated.
What causes a plant to wilt?
The cells lose turgor pressure.
How does the plasma membrane stop most substances from crossing it?
The nonpolar fatty acid tails form a barrier to polar substances
When cells are exposed to very cold conditions, the plasma membranes will respond by being less fluid and become stiff. Which of the following would explain why prolonged cold exposure leads to lack of sensitivity in neurons?
The stiffness of plasma membranes interferes with the channel proteins responsible for transmitting nerve impulses.
What do channel proteins, aquaporins, and carrier proteins have in common?
They all perform facilitated diffusion
In which direction is water most likely to move if there is a membrane and if there is a concentration difference between two regions?
Water will move out of a hypotonic solution into a hypertonic solution.
Which of the following factors will accelerate the rate of simple diffusion of molecules across a plasma membrane?
a concentration gradient of particles created by an uneven distribution of particles on either side of the plasma membrane
The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of
active transport.
Which of the following would be likely to raise the concentration of calcium ions in a cell?
blocking ATP binding sites
Aquaporins are specialized channel proteins that help water quickly shuttle across plasma membranes. Which set of cells or cellular components would one predict will have a higher amount of aquaporins based on their need for rapid osmotic response?
central vacuole of plant cells, kidney cells, and red blood cells
What simple property causes molecules to diffuse from a high concentration toward a lower concentration?
continuous random motion of molecules
The primary role of _____ is to bind animal cells together.
desmosomes
Pinocytosis is one form of ----- , the movement of large materials into a cell by an infolding of the plasma membrane.
endocytosis
The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of
endocytosis
Which membrane proteins increase the rate of chemical reactions?
enzymatic proteins
------- is the movement of materials out of a cell through the fusion of a transport vesicle with the plasma membrane.
exocytosis
At the site of the rough endoplasmic reticulum, proteins that are destined for secretion are manufactured. Insulin is a protein-based hormone made by cells in the pancreas. Which type of vesicular transport is involved with the exporting of these protein-based hormones into the bloodstream?
exocytosis
A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of
facilitated diffusion
Which type of transport requires assistance from membrane proteins but requires no energy?
facilitated diffusion
Identify Structure A
glycoprotein
What is the word for membrane proteins that have carbohydrates attached to them?
glycoprotein
A(n) ----- solution has a higher concentration of dissolved particles than an adjacent solution.
hypertonic
This cell is in a(n) ________ solution.
hypertonic
You know that this cell is in a(n) _______ solution because it ________.
hypertonic solution, lost water
A(n) ------ solution has a lower concentration of dissolved particles than an adjacent solution.
hypotonic
You know that this cell is in a(n) ______ solution because the cell ______.
hypotonic, swelled
A neurotransmitter, such as acetylcholine, is received by a plasma membrane protein, and a cascade of reactions subsequently occurs causing the cell to initiate activation or stimulation of a neuron. This process is referred to as____________.
indirect receptor action
Endocytosis moves materials _____ a cell via _____.
into, membranous vesicles
A(n) ------ solution has the same concentration of dissolved particles as an adjacent solution.
isotonic
In active transport,
molecules move across the plasma membrane against their concentration gradient.
When molecules move down their concentration gradient, they move from where they are __________ to where they are ___________.
more concentrated, less concentrated
Where Can the phosphate portion of the phospholipids in a membrane be found?
on the surfaces of the bilayer, facing the outside liquid or the cytoplasm inside
What name is given to the process by which water crosses a selectively permeable membrane?
osmosis
A cell has no membrane proteins at all. Which substance will diffuse across the membrane the fastest?
oxygen
Diffusion across a biological membrane is called
passive transport
Facilitated diffusion is a type of _________.
passive transport
------- is the movement of large materials into a cell by wrapping extensions of the plasma membrane around the material and engulfing it by fusing the extensions together.
phagocytosis
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis
Some white blood cells in the human body are able to engulf bacteria and destroy them. What should this engulfing process be called?
phagocytosis
Identify Structure D
phospholipid bilayer of membrane
Thermus aquaticus is a species of archaebacteria that grows in steaming hot springs. What would you expect to find in the plasma membrane of this species?
phospholipids with saturated fatty acid tails
Which method of transport can a cell use to bring in molecules without allowing them to pass through the plasma membrane?
receptor-mediated endocytosis
Structure A is ______.
solute
What is the function of Structure E?
stabilization of the phospholipids
You can recognize the process of pinocytosis when _____.
the cell is engulfing extracellular fluid
Water crosses the plasma membrane
through facilitated diffusion or diffusion.
Which of these cell junctions form a barrier to the passage of materials?
tight junctions
Structure A in the figure is a(n) _____.
transport protein
Structure B is a _______.
transport protein
Embedded within the phospholipid bilayer surrounding a cell are ------ , which regulate the movement of hydrophilic molecules from one side of the plasma membrane to the other.
transport proteins
Which of these would you add to a membrane to make it easier for membrane proteins to move about?
unsaturated phospholipids
As a cell gets larger, which measurement of the cell increases the fastest?
volume
