Cell Transport Mechanisms & Permeability
Why is the "plasma membrane" said to be, "Selectively permeable?"Molecular composition of the plasma membrane allows it to be selective about what passes through it. It allows nutrients and appropriate amounts of ions to enter the cell and keeps out undesirable substances.
Name the two basic ways that transport through the plasma membrane occurs:1. Passive processes
2. Active Processes
Define "passive processes"the transport process is driven by concentration or pressure differences (gradients) between the interior and exterior of the cell.
Define "active processes"the cell provides energy (ATP) to power the transport.
Name two key passive processes of membrane transport & briefly define them:1. Simple diffusion:
occurs without the assistance of membrane proteins.
2. Facilitated diffusion:
requires a membrane bound carrier protein that assists in the transport.
Define and/or describe, "osmosis"a special type of diffusion across a membrane. Water moves with its concentration gradient, from a higher concentration of water to a lower concentration of water. Movement is in response to a higher concentration of solutes on the other side of a membrane.
Define: Filtration....in the bodyPassive process. Usually occurs only across capillary walls. Depends upon a, "pressure gradient" as its driving force. Not a selective process. It si dependent upon the size of the pores in the filter.
List and briefly describe the two key ACTIVE processes: 1. Active Transport ... uses a membrane bound carrier protein like diffusion. Active transport differs from Facilitated diffusion because the solutes move AGAINST their concentration gradient & ATP is used to power the transport.
2. Vesicular transport ... Includes phagocytosis, endocytosis, pinocytosis, and exocytosis.
Define concentration gradient: Difference in concentration
Define diffusion: the movement of molecules from a region of their higher concentration to a region of their lower concentration.
What is the driving force behind diffusion: the kinetic energy of the molecules themselves.
Name the three things a membrane is called if it allows some solute particles (molecules) to pass but not others.
1. Selectively permeable
2. Differentially permeable
3. Semipermeable
The diffusion of solute particles dissolved in water through a selectively permeable membrane is called: Simple diffusion
The diffusion of water through a differentially permeable membrane is called:Osmosis
What does, "MWCO" stand forMolecular Weight Cut Off
What is Avogadro's Number?6.02 x 10 to the 23rd molecules/mole
Avagadro's number is a constant for the number of:molecules
Define and/or describe "facilitated diffusion"solutes combine with carrier-protein molecules in the membrane and are then transported with their concentration gradient. The cell does NOT have to expend the energy of ATP
Molecules need a carrier protein to help them move across the membrane because they are lipid insoluble or they are too large
Facilitated diffusion movement ispassive and down the concentration gradient
The variable that affects osmotic pressure is:the concentration of nondiffusing solutes
Filtration is a process that ...is passive
Filtration is dependent on ....a hydrostatic pressure gradient
Whenever a cell uses cellular energy (ATP) to move substances across its membrane the process is an ....active transport process.
Carrier proteins are commonly called......Solute pumps
Name two substances that are moved into cells by solute pumps....1. amino acids
2. some sugars
Membrane carrier proteins that move more than one substance, such as the Na+-K+ pump, are participating in....coupled transport.
If solutes move in the same direction, the carrier is a.....symporter
If the solutes move in opposite directions, the carrier is an .....antiporter
A carrier that transports only a single solute is a .....uniporter
The sodium-potassium pump moves_____ sodium ions and ____ potassium ions simultaneously.3, 2
The lipid bilayer is a barrier to ....hydrophilic molecules.
The process by which molecules move into and out of cells is called......membrane transport
Nonpolar molecules can permeate the plasma membrane and will simply move across the membrane by ....diffusion
Glucose and amino acids are transported across the membrane by .....carrier proteins
Molecules such as water and ions, can move through .....channels
Briefly describe the 3 types of cell adhesions, and give an example of where each is found.
1. Tight Junctions
epithelial tissue that is specialized for molecular transport.
Gastrointestinal tract or the tubules in the kidneys.
2. desmosomes
Tissues subject to mechanical stress, such as those in
the heart, uterus, and skin.
3. Gap Junctions
Smooth muscle and in the muscle of the heart.
Describe the role of transmembrane proteins in the transport of molecules across the plasma membrane.Large polar molecules that can not penetrate the lipid bylayer cross the plasma membrane using transmembrane proteins.
Even though DNA is located in the nucleus, protein synthesis takes place in the ....cytoplasm
The 3 general steps of protein synthesis are as follows:
1. DNA is TRANSCRIBED according to the genetic code to form a complementary mRNA in the nucleus.
2. mRNA moves from the nucleus to the cytoplasm.
3. mRNA is TRANSLATED by ribosomes to form the correct amino acid sequence of the protein in the cytoplasm.
Nuclear DNA comes from the mother and the father...Mitochondrial DNA only comes from the mother
Homeostasis and Cell Transport
In the space provided, write the letter of the description that best matches the
term or phrase.
_h____ 1. passive transport
__j____ 2. concentration gradient
___i___ 3. equilibrium
___a___ 4. diffusion
___k___ 5. osmosis
___b___ 6. hypertonic solution
___p___ 7. hypotonic solution
____n__ 8. isotonic solution
___f___ 9. ion channel
___e___10. carrier protein
___m___11. facilitated diffusion
____o__12. active transport
__d____13. sodium-potassium pump
____g__14. endocytosis
____c__15. exocytosis
___q___16. vesicle
___l___17. contractile vacuole
Descriptions
a. movement of a substance down the
substance’s concentration gradient
b. causes a cell to shrink because of
Osmosis
c. movement of a substance by a
vesicle to the outside of a cell
d. an example of a cell membrane “pump”
e. protein used to transport specific
substances across a membrane
f. transport protein through which ions
can pass
g. movement of a substance by a
vesicle to the inside of a cell
h. does not require energy from the cell
i. concentration of molecules is equal
throughout a space
j. difference in the concentration of
molecules across a space
k. diffusion of water through a
Membrane
l. organelle that pumps water out of
the cell
m. passive transport using carrier
Proteins
n. concentration of both solutions is
Equal
o. movement of a substance against the
substance’s concentration gradient
p. causes a cell to swell because of
Osmosis
q. organelle that fuses with lysosomes in
order that contents can be digested
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Modern Biology 9 Vocabulary Review
Why is the "plasma membrane" said to be, "Selectively permeable?"Molecular composition of the plasma membrane allows it to be selective about what passes through it. It allows nutrients and appropriate amounts of ions to enter the cell and keeps out undesirable substances.
Name the two basic ways that transport through the plasma membrane occurs:1. Passive processes
2. Active Processes
Define "passive processes"the transport process is driven by concentration or pressure differences (gradients) between the interior and exterior of the cell.
Define "active processes"the cell provides energy (ATP) to power the transport.
Name two key passive processes of membrane transport & briefly define them:1. Simple diffusion:
occurs without the assistance of membrane proteins.
2. Facilitated diffusion:
requires a membrane bound carrier protein that assists in the transport.
Define and/or describe, "osmosis"a special type of diffusion across a membrane. Water moves with its concentration gradient, from a higher concentration of water to a lower concentration of water. Movement is in response to a higher concentration of solutes on the other side of a membrane.
Define: Filtration....in the bodyPassive process. Usually occurs only across capillary walls. Depends upon a, "pressure gradient" as its driving force. Not a selective process. It si dependent upon the size of the pores in the filter.
List and briefly describe the two key ACTIVE processes: 1. Active Transport ... uses a membrane bound carrier protein like diffusion. Active transport differs from Facilitated diffusion because the solutes move AGAINST their concentration gradient & ATP is used to power the transport.
2. Vesicular transport ... Includes phagocytosis, endocytosis, pinocytosis, and exocytosis.
Define concentration gradient: Difference in concentration
Define diffusion: the movement of molecules from a region of their higher concentration to a region of their lower concentration.
What is the driving force behind diffusion: the kinetic energy of the molecules themselves.
Name the three things a membrane is called if it allows some solute particles (molecules) to pass but not others.
1. Selectively permeable
2. Differentially permeable
3. Semipermeable
The diffusion of solute particles dissolved in water through a selectively permeable membrane is called: Simple diffusion
The diffusion of water through a differentially permeable membrane is called:Osmosis
What does, "MWCO" stand forMolecular Weight Cut Off
What is Avogadro's Number?6.02 x 10 to the 23rd molecules/mole
Avagadro's number is a constant for the number of:molecules
Define and/or describe "facilitated diffusion"solutes combine with carrier-protein molecules in the membrane and are then transported with their concentration gradient. The cell does NOT have to expend the energy of ATP
Molecules need a carrier protein to help them move across the membrane because they are lipid insoluble or they are too large
Facilitated diffusion movement ispassive and down the concentration gradient
The variable that affects osmotic pressure is:the concentration of nondiffusing solutes
Filtration is a process that ...is passive
Filtration is dependent on ....a hydrostatic pressure gradient
Whenever a cell uses cellular energy (ATP) to move substances across its membrane the process is an ....active transport process.
Carrier proteins are commonly called......Solute pumps
Name two substances that are moved into cells by solute pumps....1. amino acids
2. some sugars
Membrane carrier proteins that move more than one substance, such as the Na+-K+ pump, are participating in....coupled transport.
If solutes move in the same direction, the carrier is a.....symporter
If the solutes move in opposite directions, the carrier is an .....antiporter
A carrier that transports only a single solute is a .....uniporter
The sodium-potassium pump moves_____ sodium ions and ____ potassium ions simultaneously.3, 2
The lipid bilayer is a barrier to ....hydrophilic molecules.
The process by which molecules move into and out of cells is called......membrane transport
Nonpolar molecules can permeate the plasma membrane and will simply move across the membrane by ....diffusion
Glucose and amino acids are transported across the membrane by .....carrier proteins
Molecules such as water and ions, can move through .....channels
Briefly describe the 3 types of cell adhesions, and give an example of where each is found.
1. Tight Junctions
epithelial tissue that is specialized for molecular transport.
Gastrointestinal tract or the tubules in the kidneys.
2. desmosomes
Tissues subject to mechanical stress, such as those in
the heart, uterus, and skin.
3. Gap Junctions
Smooth muscle and in the muscle of the heart.
Describe the role of transmembrane proteins in the transport of molecules across the plasma membrane.Large polar molecules that can not penetrate the lipid bylayer cross the plasma membrane using transmembrane proteins.
Even though DNA is located in the nucleus, protein synthesis takes place in the ....cytoplasm
The 3 general steps of protein synthesis are as follows:
1. DNA is TRANSCRIBED according to the genetic code to form a complementary mRNA in the nucleus.
2. mRNA moves from the nucleus to the cytoplasm.
3. mRNA is TRANSLATED by ribosomes to form the correct amino acid sequence of the protein in the cytoplasm.
Nuclear DNA comes from the mother and the father...Mitochondrial DNA only comes from the mother
Homeostasis and Cell Transport
In the space provided, write the letter of the description that best matches the
term or phrase.
_h____ 1. passive transport
__j____ 2. concentration gradient
___i___ 3. equilibrium
___a___ 4. diffusion
___k___ 5. osmosis
___b___ 6. hypertonic solution
___p___ 7. hypotonic solution
____n__ 8. isotonic solution
___f___ 9. ion channel
___e___10. carrier protein
___m___11. facilitated diffusion
____o__12. active transport
__d____13. sodium-potassium pump
____g__14. endocytosis
____c__15. exocytosis
___q___16. vesicle
___l___17. contractile vacuole
Descriptions
a. movement of a substance down the
substance’s concentration gradient
b. causes a cell to shrink because of
Osmosis
c. movement of a substance by a
vesicle to the outside of a cell
d. an example of a cell membrane “pump”
e. protein used to transport specific
substances across a membrane
f. transport protein through which ions
can pass
g. movement of a substance by a
vesicle to the inside of a cell
h. does not require energy from the cell
i. concentration of molecules is equal
throughout a space
j. difference in the concentration of
molecules across a space
k. diffusion of water through a
Membrane
l. organelle that pumps water out of
the cell
m. passive transport using carrier
Proteins
n. concentration of both solutions is
Equal
o. movement of a substance against the
substance’s concentration gradient
p. causes a cell to swell because of
Osmosis
q. organelle that fuses with lysosomes in
order that contents can be digested
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Modern Biology 9 Vocabulary Review