BIo 156 Chap 5 pt A
Identify Structure A
-glycoprotein Structure A is composed of both a carbohydrate and a protein.
After reading Example 1, you will be ready to answer this question. Do fish drink?
Although freshwater fish do not drink, saltwater fish must drink because they lose too much water through their gills.
Learning through Art: Functions of Membrane Proteins
First drag pink labels to pink targets to identify some components associated with the plasma membrane. Then drag blue labels to blue targets to identify the main functions of membrane proteins.
There is a net diffusion of water out of an animal cell when it is placed in a(n) ___ solution.
Hypertonic
An animal cell placed in a(n) ____ solution will gain water, swell, and possibly burst.
Hypotonic
The ideal osmotic environment for a plant cell is a(n) ___ environment
Hypotonic
The ideal osmotic environment for an animal cell is a(n) ____ environment
Isotonic
After reading Example 4 on food in the frig, you will be ready to answer this question. Why does jelly last so long in the frig?
Jelly contains so much sugar that it creates a hypertonic environment, inhibiting the growth of bacteria and mold.
After reading "Example 3: Water, water everywhere, and not a drop to drink!" you will be ready to answer this question. Why can't we drink seawater?
The salts in the saltwater cause water to be pulled out of our tissues, causing dehydration.
Diffusion
a form of passive transport. molecules move across the plasma membrane by crossing the lipid bilayer
facillitated diffusion
a form of passive transport. molecules move across the plasma membrane using a transport protein
In this diagram of the plasma membranes of two adjoining cells, identify the protein indicated by the white arrow, including its function.
a receptor protein that binds with a signaling molecule and relays the message into the cell by activating other molecules inside the cell Signaling proteins are part of signal transduction pathways that transmit external chemical signals into the cell.
In facilitated diffusion, a molecule cannot cross a biological membrane unless ___ is present
a transport protein
Which of these processes can move a solute against its concentration gradient?
active transport
Which of these processes requires energy?
active transport
Which of the following is a difference between active transport and facilitated diffusion
active transport requires energy from ATP and facilitated diffusion does not
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. The sodium-potassium pump moves ions across the plasma membrane against their concentration gradients. This requires energy and is an example of active transport.
A cell that neither gains nor loses water while sitting in a solution is probably sitting in
an isotonic environment.
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 In endocytosis, the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.
A white blood cell is capable of producing and releasing thousands of antibody molecules every second. Antibodies are large, complex protein molecules. How would you expect them to leave the cell?
exocytosis
The export of macromolecules out of the cell by means of a membrane-enclosed vesicle moving to the plasma membrane is called:
exocytosis
If a large hormone molecule is produced inside a cell, the hormone can be released out into the extracellular environment by:
exocytosis.
Which of the following requires specific transport proteins?
facilitated diffusion active transport
Which of the following function as cell identification tags that can be recognized by other cells?
glycoproteins and glycolipids
What is the role of cholesterol molecules that are embedded in the membranes of some living things?
help stabilize the phospholipids at body temperature
This cell is in a(n) _____ solution.
hypertonic There is a greater concentration of solute outside the cell.
You know that this cell is in a(n) _____ solution because it _____.
hypertonic solution ... lost water
Endocytosis moves materials _____ a cell via _____.
into ... membranous vesicles The prefix "endo-" means "inward."
In active transport,
molecules move across the plasma membrane against their concentration gradient.
What type of molecules pass most easily through plasma membranes?
nonpolar molecules because they are soluble in lipids
What name is given to the process by which water crosses a selectively permeable membrane?
osmosis is the passive transport of water
If the salt concentration inside a cell is 0.9%, and the salt concentration outside a cell is 9%, in which direction will there be a net movement of water by diffusion?
out of the cell
Which type of molecule is the main component of cell membranes?
phospholipids
Which of the following describes a phospholipid molecule?
polar head, hydrophobic tail
A human cell placed in a hypotonic environment would
take up water through osmosis
Many bacteria and fungi have a difficult time surviving on our food if the food is very salty. The best explanation for this is
that the salt in the food creates a hypertonic environment for the bacteria and fungi.
Which of the following has the greatest effect on the ability of polar molecules to pass through membranes?
the protein carriers that are present in the membrane
If placed in distilled water, an animal cell will burst, whereas a plant cell will not. What accounts for this difference?
the relative inelasticity and strength of the plant cell wall
You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells?
the similarity of the drug molecule to other molecules that are transported into the target cells If the target cells have transport proteins that specifically bind to certain molecules, they may bind with and transport a drug that is similar in structure.
Water crosses the plasma membrane
through facilitated diffusion or diffusion. Water can cross the plasma membrane through the process of facilitated diffusion. However, water molecules can also cross the lipid bilayer directly.
Structure A in the figure is a(n) _____.
transport protein
Facilitated diffusion across a biological membrane requires ___, and moves a substance from ___ concentration.
transport proteins; high to low
After reading Example 2, on diarrhea and constipation, you will be ready to answer this question. Why might a salty laxative help relieve constipation?
Salty laxatives in the large intestine help pull water out of cells and into the intestine by osmosis, thereby relieving constipation.
In a plant cell, if there is a net inflow of water keeping pressure exerted against the inside of the cell wall, the cell must be in ___ environment.
a hypotonic
The movement of molecules from higher concentration to lower concentration is called:
diffusion
Which of the following best describes the plasma membrane?
fluid mosaic
If the solution outside of a cell has a greater concentration of solutes than the solution inside the cell, the solution outside the cell is ___ in relation to the cell
hypertonic
If the solution outside of a cell has a lower concentration of solutes than the solution inside the cell, the solution outside the cell is ___ in relation to the cell.
hypotonic
Some protists (like Paramecium) have special organelles called ontractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment is ___ to the protist.
hypotonic
You know that this cell is in a(n) _____ solution because the cell _____.
hypotonic ... swelled A cell will gain water when placed in a hypotonic solution.
A human cell placed into a hypertonic solution is likely to
lose water by osmosis.
Endocytosis
process by which a cell takes material into the cell by infolding of the cell membrane
In an aqueous environment, phospholipids tend to organize into a bilayer because the formation of a bilayer:
shields the hydrophobic tails from water.
When a person is dehydrated, his or her IV fluids
should be isotonic, because either a hypertonic or hypotonic IV would damage red blood cells.
Structure A is a _____.
solute A solute is crossing the plasma membrane.
Which of the following is a function of membrane proteins?
some proteins are involved in transport, and help move substances across the membrane some proteins are enzymes involved in catalytic reactions some proteins function as receptors for chemical messengers from other cells some proteins are receptors involved in signal transduction
What does it mean if the plasma membrane exhibits selective permeability?
some substances can cross the membrane more easily than other substances
What is the function of Structure E?
stabilization of the phospholipids Cholesterol helps to stabilize the structure of the plasma membrane.
Which of the following will happen to an animal cell if placed in a hypotonic environment?
the cell will become larger, and may burst
If a cell is in equilibrium with its environment:
the environment is probably isotonic to the cell
Which of the following can move across membranes by passive transport?
water oxygen carbon dioxide
Diffusion across a biological membrane is called
passive transport
You can recognize the process of pinocytosis when _____.
the cell is engulfing extracellular fluid Pinocytosis is "cell drinking."
What is osmoregulation?
the control of water balance
Which of these is hydrophobic like the interior of the plasma membrane?
A Lipid soluble molecules are hydrophobic.
Hypertonic
A plant cell placed in a(n) ___ solution will lose water and plasmolyze.
If you are going to bake potatoes, and your potatoes are soft and dehydrated, they can be soaked in __________ to make them more firm before baking.
a hypotonic solution such as tap water
When diffusion across a membrane stops because a state of dynamic equilibrium is reached, it means that:
an equal number of molecules are moving in and out, so there is no net movement.
What type of organism has cholesterol in it's membranes?
animals
Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements.
-Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. -The diverse proteins found in and attached to membranes perform many important functions -The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center. Membranes consist of diverse proteins suspended in and attached to a phospholipid bilayer. Kinks in the unsaturated fatty acid tails of some phospholipids keep the membrane fluid, and a mosaic of proteins perform a variety of functions.
Identify Structure D
-phospholipid bilayer of membrane Phospholipids can be recognized by the presence of a head and two tails.
Exocytosis
A vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell.
After reading Example 5 on reverse osmosis filters, you will be ready to answer this question. Why are they called "reverse osmosis filters?"
Because high pressure is used to push water through a filter, against the concentration gradient.
Which of the following is NOT a true statement about diffusion?
Diffusion occurs when particles spread from areas of low concentration to areas of high concentration
Exocytosis
a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.
Chapter 5 covers membranes, membrane transport, energy, and enzymes -- all of which are important structures or processes in cells. Which of the types of biological macromolecules from Chapter 3 will be important in Chapter 5?
carbohydrates, lipids, proteins
A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example
facilitated diffusion. In facilitated diffusion, molecules use a transport protein to move across the plasma membrane. There is a net movement of molecules down the concentration gradient -- that is, there is a net movement of molecules from where they are more concentrated to where they are less concentrated.
Paramecium is a genus of protists that lives in water. It has organelles called contractile vacuoles that continually eliminate the excess water gained through osmosis. Knowing that Paramecia gain water through osmosis, we can deduce that they normally live in
freshwater lakes and ponds.
If the solutions both inside and outside of a cell have an equal concentration of solutes, the solution outside the cell is ___ in relation to the cell.
isotonic
In a hypertonic environment, a plant cell will:
lose the water from the central vacuole, and the cell membrane will pull away from the cell wall
When molecules move down their concentration gradient, they move from where they are _____________ to where they are _______________.
more concentrated less concentrated
Facilitated diffusion is a type of _____.
passive transport During facilitated diffusion, the cell is not expending energy to move the particles across the membrane; therefore, facilitated diffusion is a form of passive transport.
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis Phagocytosis occurs when a cell engulfs a large particle
Sodium ions require energy to move across a plasma membrane. The movement of sodium ions across a membrane
requires a transport protein
acrive transport
requires energy from the cell. molecules move against their concentration gradient
Endocytosis
the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell
Structure B is a _____.
transport protein The transport protein facilitates the movement of solute across the plasma membrane.
Which of the following can move across membranes by diffusion?
water oxygen carbon dioxide