Biology Chapter 5
Which of the following are required for the sodium potassium pump in cells to work?
ATP and Carrier proteins.
Transport that requires a cell to expend some of its own energy, typically from ______________, is called _______________ transport.
ATP, active
Channel proteins that can opened or closed in response to a specific stimulus are called ________ channels.
gated
The backbone of triglycerides and phospholipids is derived from ______________.
glycerol
An aqueous solution with a lower concentration of solutes will have a __________ concentration of free water molecules.
higher
Water is attracted to charged or polar solutes, forming _________ shells around them.
hydration
The combined concentration of all solutes in a solution determines the ___________ _________ of the solution.
osmotic concentration
The force needed to stop the net inflow of water into a solution by osmosis is called _____________ ___________.
osmotic pressure
Transport that occurs without a cell expending any of its own energy is called ________ transport.
passive
Endocytosis of discrete particles is called _______ while endocytosis of liquids is called ________.
phagocytosis, pinocytosis
All cell membranes are composed of _________ in a bilayer which provides a flexible __________ and provides a barrier to permeability.
phospholipids, matrix
The thin structure made of a bilayer of lipids with embedded proteins that surrounds all cells is called the _______ ________.
plasma membrane
Which structure surrounds all cells?
plasma membrane
Transmembrane B-Sheets from a motif through the membrane that allows molecules to pass through the membrane. This structure is called a ______________.
pore protein
According to the fluid mosaic model of membrane structure, a mosaic of _____________ floats in or one a fluid ______________ ____________.
proteins, lipid bilayer
During ______________ __________ endocytosis, molecules bind to specific protein receptors in the plasma membrane before they are engulfed by the cell.
receptor-mediated
Low-density lipoprotein (LDL) enters the cell by what process?
receptor-mediated endocytosis
Which of the following cell types use exocytosis to discharge materials from the cell?
Eukaryotics (Protist, plant, animal)
Which of the following are mechanisms of bulk transport?
Exo and Endocytosis
T/F: In plant cells, exocytosis provides a mechanism for secreting hormones, neurotransmitters, and digestive enzymes through the plasma membrane.
F
When a channel protein or carrier protein assists in diffusion, which of the following is observed?
Facilitated diffusion
T/F: Regarding the Na/K pump: phosphorylation of the protein which reduces its affinity for Na+ occurs after dephosphorylation of the protein reduces its affinity for K+.
False
The following substances all move across the plasma membrane of red blood cells by diffusion. Which ones move by facilitated diffusion?
Glucose, Bicarbonate ions, Chloride ions.
The plasma membrane's cell surface markers include which of the following?
Glycolipids and Glycoproteins
What is the immediate source of the energy needed to power the sodium-potassium pump?
Hydrolysis of ATP
The four main components of all eukaryotic membranes.
Interior protein network, Cell surface markers, Lipid bilayer, and Transmembrane proteins.
Examples of how an interior protein network structurally support the membrane include:
Intracellular proteins anchor membrane proteins. A protein in red blood cells called spectrin links proteins in the plasma membrane to actin filaments.
In cell membranes, the interior of the lipid bilayer repels which of the following?
Ions, Hydrophillic molecules, polar molecules
Why do phospholipids form bilayers when mixed with water?
It allows the nonpolar tails to avoid contact with water.
Which of the following describes the surface of a phospholipid bilayer?
It is polar or charged. It is hydrophillic.
Which of the following are true of the plasma membrane?
It is selectively permeable. It is fluid.
Which of the following describes the sodium-potassium pump?
It uses NRG from ATP to alter the conformation of the carrier protein. It is an active transport mechanism. It moves sodium ions and potassium ions across the membrane in opposite directions.
Which of the following accurately describes the hydrostatic pressure inside a cell if it is transferred from a hypertonic environment to a hypotonic environment?
It will increase
True statements concerning the organization of the plasma membrane.
Lipids can exist in either an ordered or disordered phase within the membrane. The plasma membrane is not homogeneous. The plasma membrane contains areas with distinct lipid and protein composition.
Which of the following best describes the amount of energy used by animal cells in the active transport of Na+ and K+ from areas of low concentration to areas of high concentration?
More than one-third of all energy expended by an animal cell that is not actively dividing is used in the transport of Na+ and K+.
In human patients with familiar hypercholesterolemia which of the following occurs?
The LDL receptors lack tails so they are not fastened in the clatherin-coated pits and do not trigger vesicle formation.
In which of the following is ATP used directly in active transport?
The Tranport of Na^+ across the plasma membrane.
If a cell is placed in a hypertonic solution what occurs?
The cell will tend to shrink. Net movement of water is out of the cell.
Diffusion is caused by which of the following?
The constant random motion of all atoms and molecules.
During receptor-mediated endocytosis, binding of the target molecules to their matching receptors triggers what?
The formation of an endocytic vesicle
Why does a plasma membrane act as a barrier to the free passage of water-soluble substances?
The interior of the lipid bilayer is hydrophobic.
Which statements are true regarding endocytosis?
The plasma membrane envelops food particles and fluids. Once material enter the cell they are still separated from the cytoplasm by the membrane of a vacuole or vesicle.
Select the accurate statements concerning membrane fluidity.
Unanchored proteins are relatively free to move around laterally within the membrane. Phospholipids are relatively free to move around laterally within the membrane. The degree of membrane fluidity varies depending on the composition of the membrane.
The diffusion of these molecules across a selectively permeable membrane is called osmosis.
Water
Which of the following best describes the ability to move across the lipid bilayer membrane, such as the plasma membrane?
Water can move across the lipid bilayer, but the flow is lipid.
In a living cell, the plasma membrane does not allow the free passage of water-soluble substances. Why?
Water-soluble substances are repelled by the interior of the lipid bilayer.
Carrier proteins that transport 2 different types of molecules or ions in opposite directions are called
antiporters
The movement of water across the plasma membrane is facilitated by specialized water channels called ___________
aquaporins
Why do ions need membrane transport proteins to help them cross the plasma membrane?
b/c of their charge
Amino acids, sugars and ions are transported across the plasma membrane by ______________ proteins.
carrier
Of the 2 types of transport proteins that mediate facilitated diffusion, only ________ proteins actually bind with the substance being transported while ________ proteins simply provide a hydrophillic space for the substance to move through.
carrier, channel
Proteins which are embedded in the membrane are called ______________ membrane proteins, while proteins which are attached to the surface of the membrane are called _______ proteins.
integral; peripheral
Ions that carry an overall positive charge are called ___________ while those that carry an overall negative charge are called __________.
cations, anions
Transport proteins that have a hydrophillic interior space through which specific substances can move across the membrane in either direction are called _______ proteins.
channel
Many substances that are repelled by the hydrophobic interior of the lipid bilayer can readily diffuse acoss the plasma membrane with the help of specific ________ proteins or ________ proteins.
channel; carrier
Ion ________ have hydrated interior that spans the membrane and allows ions to diffuse through.
channels
During ___________ transport, carrier proteins use the energy in one substance's concentration _________ to actively transport another substance.
coupled, gradient
If a cell is transferred from a hypotonic environment to a hypertonic environment, the hydrostatic pressure inside the cell will.
decrease
When a cell is placed in ____________ solution, water moves across the plasma membrane in both directions but there is no change in cell size.
isotonic
Due to the constant random motion of its atoms and molecules, a substance will exhibit net movement from a region where it has a higher concentration to a region where it has a lower concentration. This net movement is called __________
diffusion
The relative concentration of substance inside and outside the cell along with the ability of a substance to cross the membrane determines the rate __________ across the plasma membrane.
diffusion
Each membrane-spanning region of a transmembrane protein is called a transmembrane ______________.
domain
Examination of cell membranes using the two types of ______________ microscopy has allowed biologists to visualize the lipid bilayer of the membrane.
electron
Carrier proteins that transport 2 different types of molecules or ions may be either ________ or antiporters.
symporters
When phospholipids are placed in water, they spontaneously form which of the following?
A bilayer
When the concentration of a substance varies from one region to another, this is called which of the following?
A concentration gradient
Animal cells are more likely than plant cells to rupture when placed in which of the following solutions?
A hypotonic solution.
A defining feature of biological membranes is the presence of which of the following?
A lipid bilayer.
During the coupled transport of glucose what occurs?
As sodium moves back into the cell down its concentration gradient, it releases the energy needed to move glucose up its concentration gradient. Sodium ions move back into the cell down their concentration gradient.
Why are bacterial cells less likely than animal cells to burst in a hypotonic solution?
Bacterial cells have strong cell walls.
What are lipid rafts in cellular membranes heavily enriched in?
Cholesterol and Sphingolipids.
Compared to the ER membrane, the plasma membrane contains more of which of the following?
Cholesterol, Sphingomyelin, and Phosphatidylcholine
Which type of transport proteins use of energy from ATP indirectly?
Coupled transport proteins
Different proteins can cross the membrane in different ways. What is the primary difference between transmembrane proteins in terms of how they cross the membrane?
Different proteins can cross the membrane a different number of times.
How do active and passive transport differ?
Only active transport relies on an expenditure of energy by the cell itself, usually from ATP. Only active transport can move a substance against its concentration gradient.
Which of the following makes up the bilayer of every cell membrane?
Phospholipids
Which of the following are mechanisms of endocytosis?
Pinocytosis, Phagocytosis, and Recepter-mediated endocytosis.
Examples of Exocytosis
Plant cells export materials needed to construct the cell wall. Nerve cells secrete neurotransmitters. Animal cells secrete hormones. Cells lining the digestive tract secrete digestive enzymes.
The major barrier to crossing a biological membrane is the hydrophobic interior of the membrane that repels what kind of molecules?
Polar molecules
Key functions carried out by membrane proteins?
Receive external chemical messages. Connect adjacent cells and hold them together. Attach the membrane to the cytoskeleton.
Clathrin is used in which type of endocytosis?
Receptor-Mediated Endocytosis
How does lipid composition affect membrane fluidity?
Saturated fatty acids tend to make the membrane less fluid because they pack together well. Sterols, such as cholesterol, can either increase or decrease membrane fluidity depending on temperature.
Chose the three groups of lipids found in eukaryotic cells
Sterols, Glycerol Phospholipids, and Sphingolipids
T/F: NRG released from the hydrolysis of ATP is used to change the conformation of the sodium-potassium pump which results in changes in the protein's affinity for Na+ and K+.
T
The ER membrane is typically more fluid than the plasma membrane and it contains more curvature. Why?
The ER membrane contains mainly unsaturated phospholipids.
If 2 solutions have unequal concentrations of solutes, which one will be considered hypertonic?
The solution with the higher solute concentration.
Some membrane proteins are attached to the surface of the membrane by special molecules that associate strongly with phospholipids. Which of the following describes the anchoring molecules?
They are modified lipids. They have chemical bonding domains that link them directly to the membrane proteins.
During facilitarted diffusion, how do carrier proteins transport solutes across the membrane?
They bind specifically to the solute being transported.
Which of the following represents the highest rate of endocytosis expressed in white blood cells?
They can ingest up to 25% of their cell volume per hour.
Statements that are true regarding gated channels.
They have a hydrated interior through which polar molecules and ions can move when open. They can open and close in response to chemical stimuli. They can open and close in response to electrical stimuli.
Which of the following is true of channel proteins?
They have a hydrophillic interior through which polar molecules can pass.
T/F: In order to survive, grow, and reproduce, a cell must continually exchange materials and information with its environment.
True
Carrier proteins that transport 2 different types of molecules or ions in the same direction are called
symporters
The lack of double bonds in saturated fats allow them to pack together tightly, and therefore the membrane is _______________ fluid. The presence of double bonds is unsaturated fats prevent them from packing together tightly, and therefore the membrane is _____________ fluid.
less, more
Cellular ________ are said to be selectively ____________ because they allow some substances to pass through easily while other substances pass through very slowly or not at all.
membranes, permeable
The active glucose transporter moves ____________ down its concentration gradient and __________ against its concentration gradient.
sodium; glucose
The combined concentration of all ________ in a solution determines the osmotic concentration of the solution.
solutes
The cytoplasm contains ions and molecules dissolved in ______________.
water
The movement of __________ and other small hydrophilic molecules across a membrane is facilitated by specialized channels called aquaporins.
water
When 10 grams of sugar are dissolved in 1 L of water, ________ is the solved and ______ is the solute.
water, sugar
