Membrane Transport
___________ involves moving large particles into the cell
Endocytosis
examples: Ions
Na, K, Cl
According to the second law of thermodynamics, which of the following is true?
The ordering of one system depends on the disordering of another.
______ _______ are embedded in the cell membrane & have a pore for materials to cross; examples: ___
___, ___, ___, channel proteins
During enzymatic reactions, substrates are converted to products. A property of enzymes that facilitates this reaction is that they are catalysts and therefore _____.
change the rate of a reaction without being consumed by the reaction. This permits enzyme molecules to be used repeatedly.
Heating inactivates enzymes by
changing the enzyme's three-dimensional shape.
______ occurs whenever water moves into the cells causing them to swell and burst
cytolysis
Fluid inside the cell is called _____.
cytosol
High temperatures or changes in pH can ________ an enzyme, causing it to lose its shape and biological activity.
denature
The movement of molecules from an area of higher concentration to an area of lower concentration is called _____.
diffusion
Explain what happens to a drop of food coloring put into a beaker of water
diffusion happens until the dye and the water reach equilibrium
__________ is the opposite of exocytosis
endocytosis
Homeostasis is also called ______
equilibrium
When a cell uses chemical energy to perform work, it uses the energy released from a(n) ________ reaction to drive a(n) ________ reaction.
exergonic . . . endergonic
When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will
exhibit a net movement to the side with lower free water concentration.
Moving very large particles out of the cell is called _________
exocytosis
A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of
facilitated diffusion
During ______ _______ integral proteins assist molecules in moving through the membrane; needs a membrane; however no energy is needed
facilitated diffusion
______ diffusion is a type of _____ transport because energy is NOT required
facilitated, passive
_______ diffusion uses _____ proteins to help move materials from _____ to ____ concentrations
facilitated, transport, high to low
cell membranes of unicellular organisms are _______ so the organism can move
flexible
Channel proteins have an opening or _____ through which molecules can passively move by ________ diffusion
gated, facilitated
Are phospholipids heads polar or non-polar? the tails?
heads=polar
In cellular respiration, most energy is released and transferred to ATP when _____.
high-energy electrons "fall" to lower energy levels
The _______ ___ between an active site and its substrate often strains bonds and helps the reaction proceed.
induced fit
When an enzyme catalyzes a reaction,
it lowers the activation energy of the reaction.
Light is _____ energy, which is converted by plants into molecules, which possess _____ energy.
kinetic ... chemical
Materials soluble in ______ can pass easily through the cell membrane
lipids
How does the plasma membrane help maintain homeostasis?
maintained by plasma membrane controlling what enters and leaves the cell
In active transport,
molecules move across the plasma membrane against their concentration gradient.
With simple diffusion
molecules move from an area of ______ concentration to an area of _____ concentration, HIGH, LOW
White blood cells engulfing bacteria is an example of _________
phagocytosis
______ occurs whenever water moves out of a cell & the cell shrinks in size
plasmalysis
What causes the mosaic pattern of the cell membrane when viewed from above?
proteins
Overall, membranes seem to have a great deal in common, but on closer inspection it is revealed that membranes of different cells have unique properties. What is the primary component of membranes that gives membranes cell-specific properties?
proteins. There is a large variety of proteins, and it is differences in these widely varying molecules that give a particular membrane its unique properties.
________ _________ endocytosis involves protein __________ recognizing hormones to help move them into the cell
receptor mediated, receptors
Simple ______
requires NO energy to move things across the cell membrane, diffusion
Anything that prevents ATP formation will most likely
result in cell death.
_______ _________ is the movement from a high concentration to a low concentration; no energy & no membrane is needed
simple diffusion
the ________ ________ pump is an example of active transport
sodium-potassium
If water potential is LOW
solute concentration ____, HIGH
In exocytosis
wastes are moved out of the cell in ______ that fuse with the cell membrane, vesicles
What are cell junctions?
where cells come in contact with eachother
name two types of transport proteins found in cell membranes
1) channel proteins
give two examples of passive transport in cells
1) movement of oxygen
active transport uses cellular energy known as ____
ATP
Requires energy from the cell. Molecules move against their concentration gradient.
Active Transport
one molecule or ion that moves in one direction using the protein
uniport
plants prefer ______ environments
while animals do best in ______ environments., hypotonic, isotonic
Reactions can be exergonic or endergonic. Which of these reactions is endergonic?
protein synthesis
Most of a cell's enzymes are
proteins.
You are adrift in the Atlantic Ocean, and, being thirsty, drink the surrounding seawater. As a result,
you dehydrate yourself.
How many fatty acid chains are in a phospholipid?
2, both are unsaturated
How does inhibition of an enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor?
Competitive inhibitors bind to the active site of the enzyme; noncompetitive inhibitors bind to a different site.
A form of passive transport. Molecules move across the plasma membrane by crossing the lipid bilayer.
Diffusion
The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains materia from outside the cell.
Endocytosis
Which of the following statements regarding enzyme function is false?
Enzymes are used up when they catalyze a chemical reaction, so must be synthesized for each new chemical reaction.
What is the basic difference between exergonic and endergonic reactions?
Exergonic reactions release energy; endergonic reactions absorb it.
A vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell.
Exocytosis
A form of passive transport. Molecules move across the plasma membrane using a transport protein.
Facilitated Diffusion
Which of the following statements about the ATP molecule is true?
It releases energy when one phosphate group leaves ATP.
List three substances that pass through the cell membrane...
Oxygen, Carbon dioxide, and water
Which of the following statements is true about passive transport?
Passive transport requires no expenditure of cellular energy.
Kinetic energy is energy in motion. Potential energy is _____ energy.
Stored.
The eukaryotic cell has multiple membrane-enclosed compartments. This evolutionary innovation provides what advantage to the cell?
The different membrane-enclosed spaces allow different parts of the cell to perform specific functions. The membranes that surround organelles make it possible to construct very different chemical environments within and on the surface of each of these organelles.
What happens to the chemical energy that is extracted from molecules by cellular activities but that is not used for cellular work?
The energy contributes to the entropy of the system. The second law of thermodynamics states that in any energy transformation, the overall disorder of the universe increases. Most often, this disorder comes in the form of thermal molecular motion (heat), which is a form of energy that is not lost but cannot be harnessed for work.
The phospholipid _____ of the cell membrane allows _______ molecules to pass through easily but
________ do not., bilayer, hydrophobic, hydrophilic
_________
_________ molecules larger than water, and large _______ molecules do NOT move easily through the phospholipids of the cell membrane., ions, hydrophilic, proteins
Energy can be classified as either potential or kinetic. Which of the following is an example of kinetic energy?
a running child
An enzyme peeds up reactions by lowering the __________ ______.
activation energy
An enzyme is specific because of the shape its ______ ____ matches only particular reactants.
active site
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.
what is meant by homeostasis?
balanced internal condition of cells
An enzyme is considered a _________ because it speeds up a chemical reaction without being used up.
catalyst
A ________, which is often a vitamin, binds to an enzyme and plays role in catalysis.
coenzyme
The fluid mosaic model describes the plasma membrane as consisting of
diverse proteins embedded in a phospholipid bilayer.
The phosphorylation of ADP to form ATP is an _____ reaction that _____ energy.
endergonic ... requires an input of
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.
Certain cells that line the stomach synthesize a digestive enzyme and secrete it into the stomach. This enzyme is a protein. Which of the following processes could be responsible for its secretion?
exocytosis
Bacterial production of the enzymes needed for the synthesis of the amino acid tryptophan declines with increasing levels of tryptophan and increases as tryptophan levels decline. This is an example of
feedback inhibition.
The_____ ______ _______ describes the appearance of the cell membrane
fluid mosaic model
When water moves toward the solution with the _____ solute concentration, the solution is _____.
greater ... hypertonic
Which of the following energy transfers is impossible in living systems?
heat to light energy
In oil-based liquids, phospholipids are arranged so that their _____ face outward and their _____ are orientated inward.
hydrophobic tails ... hydrophilic heads This arrangement shelters the hydrophilic heads of the phospholipids from the oil while exposing the hydrophobic tails to the oil. This is seen in oil-based solutions.
With diffusion
molecules move by their own natural _____ or energy of motion., energy
Which of the following is highest in chemical energy?
one molecule of Glucose
Which part of the ATP molecule breaks free of the rest when an ATP molecule is used for energy?
one phosphate group.
Because the cell membrane is ________
only _______ molecules and larger ________ molecules can move through easily., hydrophobic, small, hydrophobic
What is meant by the term selectively permeable?
only certain things can enter and leave
The diffusion of water across a cell membrane
osmosis
The diffusion of water across a selectively permeable membrane is called _____.
osmosis
Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of
passive transport.
Oxygen crosses a plasma membrane by
passive transport.
Which of the following terms specifically refers to the intake of very large particles by cells?
phagocytosis
The process of a white blood cell engulfing a bacterium is
phagocytosis.
A _______ bilayer makes up most of the cell membrane.
phospholipid
Seawater is dangerous to drink because _____.
seawater is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis
The first law of thermodynamics _____.
states that energy is neither created nor destroyed
All cells are enclosed by a plasma membrane that is similar in ________ and ________.
structure . . . function
In catalyzed reaction, a reactant is often called a _________.
substrate
The energy required to initiate an exergonic reaction is called
the activation energy.
Energy is _____.
the capacity to perform work
Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis?
the difference in water concentration across a selectively permeable membrane. The driving force for osmosis is water's concentration gradient across a selectively permeable membrane. Differences in solute concentration across a membrane create water concentration differences, but solute concentration differences do not directly drive osmosis.
What controls the direction of a molecule, such as oxygen, involved in passive transport?
the direction of the oxygen concentration gradient. The direction material moves in passive transport is determined solely by the material's concentration gradient, with material diffusing from regions of higher concentration to regions of lower concentration.
According to ________, energy cannot be created or destroyed.
the first law of thermodynamics
Plasma membranes are selectively permeable. This means that
the plasma membrane allows some substances to enter or leave a cell more easily than others.
The active site of an enzyme is
the region of an enzyme that attaches to a substrate.
Why is the cell membrane said to act like a fluid?
there is lateral movement
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.
Energy is conserved. This means that in any system, _____.
total energy input equals total energy output
Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.
transport proteins . . . down
What substance is transported by aquaporins?
water. Aquaporins are a newly discovered class of transport proteins that transport water in cells with very high water permeability needs.
Kinetic energy differs from chemical energy in that
kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules.
Explain how these carrier proteins move materials across the cell membrane.
They bind to molecules, change their shape carry it to the right side of the membrane and release it
If water potential is HIGH
solute concentration is ____, LOW
List some protein functions:
1) structural support
name to materials that move into or out of cells by facilitated diffusion
1)glucose
The sodium-potassium pump moves ___ sodium ions out for every ___ potassium ions moved into the cell creating voltage across the cell called the ___________ ____________.
3, 2, threshold potential
Water moves from ____ water potential to ____ water potential.
LOW TO HIGH
Active transport moves materials AGAINST the concentration gradient or from ____ to ____ concentration
LOW to HIGH
Do all carrier proteins extend across the cell membrane?
NO
How do carrier proteins help move materials across a cell membrane?
They change their shape to fit the material and carries it to the right side of the membrane; it also protects polar molecules
b. a concentrated salt solution
a.hypotonic
Substrates bind to an enzyme's ________ site.
active
Which of the following processes can move a solute against its concentration gradient?
active transport
________ ________ needs ATP and is the movement of concentration from low to high; may need a protein & needs a cell membrane
active transport
________ is the movement from high pressure to low pressure; occurs in the kidneys
and is a passive transport mechanism, filtration
two molecules or ions that move through the same protein but in opposite directions (one in and one out)
antiport
Water diffuses through the pores called ______ of the cell membrane.
aquaporins
How does cholesterol get into the cell?
attaches to receptor and taken in by vesicle
Why is diffusion considered a passive process?
because there is NO ATP used, only natural energy can be used
"_____ _______" is known as ___________.
cell eating, phagocytosis
passive transport does _____ require additional energy & moves materials from ____ to _____ concentration
not, high, low,
Taking in large liquid droplets is called ________ or "______ _______"
pinocytosis, "cell drinking"
2 substances move through the same protein in one direction
symport
Which of the following processes is endergonic?
the synthesis of glucose from carbon dioxide and water
When solutes diffuse through a membrane
they move from ____ to ____ concentration., HIGH to LOW