Lesson 2.4 - Transport Across Membranes Flashcards
1
Q
Define Passive Transport
A
The movement of a substance across a membrane without expending energy.
2
Q
What is the movement of a substance across a membrane without expending energy known as?
A
Passive Transport
3
Q
Define Dynamic Equilibrium
A
The state in which continuous action results in balanced conditions.
4
Q
What is the state in which continuous action results in balanced conditions known as?
A
Dynamic Equilibrium
5
Q
Define Simple Diffusion
A
The ability of small and non-polar substances to move across a membrane unassisted.
6
Q
What is the ability of small and non-polar substances to move across a membrane unassisted known as?
A
Simple Diffusion
7
Q
Define Facilitated Diffusion
A
The facilitated transport of ions and polar molecules through a membrane via protein complexes.
8
Q
What is the facilitated transport of ions and polar molecules through a membrane via protein complexes known as?
A
Facilitated Diffusion
9
Q
Define Transport Protein
A
An integral membrane protein that provides a pathway for molecules to cross a membrane.
10
Q
What is an integral membrane protein that provides a pathway for molecules to cross a membrane known as?
A
Transport Protein
11
Q
Define Channel Protein
A
A hydrophilic pathway in a membrane that enables water and ions to pass through.
12
Q
What is a hydrophilic pathway in a membrane that enables water and ions to pass through known as?
A
Channel Protein
13
Q
Define Carrier Protein
A
A protein that binds to a molecule and transports it across the lipid bilayer.
14
Q
What is a protein that binds to a molecule and transports it across the lipid bilayer known as?
A
Carrier Protein
15
Q
Define Osmosis
A
The passive diffusion of water across a membrane.
16
Q
What is the passive diffusion of water across a membrane known as?
A
Osmosis
17
Q
Define Hypotonic
A
A solution that has a lower solute concentration than another solution.
18
Q
What is a solution that has a lower solute concentration than another solution known as?
A
Hypotonic
19
Q
Define Hypertonic
A
A solution that has a higher solute concentration than another solution.
20
Q
What is a solution that has a higher solute concentration than another solution known as?
A
Hypertonic
21
Q
Define Isotonic
A
A solution that has the same solute concentration as another solution.
22
Q
What is a solution that has the same solute concentration as another solution known as?
A
Isotonic
23
Q
Define Active Transport
A
The movement of substances across membranes against their concentration gradient using pumps.
24
Q
What is the movement of substances across membranes against their concentration gradient using pumps known as?
A
Active Transport
25
Define Electrochemical Gradient
The combined effects of a difference in electrical potential energy and a difference in the concentration gradients of ions.
26
What are the combined effects of a difference in electrical potential energy and a difference in the concentration gradients of ions known as?
Electrochemical Gradient
27
Cells and cell organelles must interact with their environment by allowing and controlling the inward and outward movement of molecules and ions through their \_\_\_\_\_.
Cells and cell organelles must interact with their environment by allowing and controlling the inward and outward movement of molecules and ions through their **membrane**.
28
Some molecules can pass through a membrane using passive transport (\_\_\_\_\_ or _____ diffusion), which depends on a _____ gradient.
Some molecules can pass through a membrane using passive transport (**simple** or **facilitated** diffusion), which depends on a **concentration** gradient.
29
Osmosis is the passive diffusion of _____ across a membrane.
Osmosis is the passive diffusion of **water** across a membrane.
30
Active transport moves a substance against a _____ across a membrane, using a \_\_\_\_\_. Primary active transport pumps include H+, Ca+, Na+, and K+ pumps. Secondary transport pumps occur via symport or antiport.
Active transport moves a substance against a **concentration gradient** across a membrane, using a **pump**. Primary active transport pumps include H+, Ca+, Na+, and K+ pumps. Secondary transport pumps occur via symport or antiport.
31
Endocytosis moves aggregate molecules _____ the cell. Exocytosis moves protein and wastes _____ the cell.
Endocytosis moves aggregate molecules **into** the cell. Exocytosis moves protein and wastes **out of** the cell.
32
Passive transport is the movement of a substance across a membrane without the need to expend \_\_\_\_\_.
Passive transport is the movement of a substance across a membrane without the need to expend **energy**.
33
[Passive transport] is driven by \_\_\_\_\_, which is the movement of substances from an area of high concentration to low concentration.
[Passive transport] is driven by **diffusion**, which is the movement of substances from an area of high concentration to low concentration.
34
Membranes have selective \_\_\_\_\_, which means that some molecules can diffuse very rapidly across a membrane while other molecules are unable to transit the membrane without assistance.
Membranes have selective **permeability**, which means that some molecules can diffuse very rapidly across a membrane while other molecules are unable to transit the membrane without assistance.
35
What two factors does the rate of diffusion in active transport depend on? How do they affect the rate?
Concentration Difference (or Gradient) - The steeper the concentration gradient, the quicker they will diffuse.
Temperature - A higher temperature allows the molecules to move faster, encouraging more movement and increasing the rate of diffusion.
36
Simple diffusion is the ability of small and non-polar substances to move across a membrane _____ and without \_\_\_\_\_.
Simple diffusion is the ability of small and non-polar substances to move across a membrane **unassisted** and without **energy**.
37
[In simple diffusion,] very small _____ molecules (O2 and CO2) are readily soluble in the hydrophobic interior and therefore move rapidly from one side to the other. _____ steroid hormones and drugs also cross easily. Small, uncharged molecules (H2O and glycerol) even though polar, still move quite rapidly. Membranes are impermeable to large molecules and ions.
[In simple diffusion,] very small **non-polar** molecules (O2 and CO2) are readily soluble in the hydrophobic interior and therefore move rapidly from one side to the other. **Non-polar** steroid hormones and drugs also cross easily. Small, uncharged molecules (H2O and glycerol) even though polar, still move quite rapidly. Membranes are impermeable to large molecules and ions.
38
\_\_\_\_\_ diffusion is the _____ transport of ions and polar molecules through a membrane via protein complexes and without energy. [It] still uses the process of diffusion [like in simple diffusion], and is based on a concentration gradient but uses a protein to help substances across the membrane.
**Facilitated** diffusion is the **facilitated** transport of ions and polar molecules through a membrane via protein complexes and without energy. [It] still uses the process of diffusion [like in simple diffusion], and is based on a concentration gradient but uses a protein to help substances across the membrane.
39
Channel proteins are _____ membrane proteins that form hydro\_\_\_\_\_ pathways in the membrane, so substances like H2O and ions can cross.
Channel proteins are **integral** membrane proteins that form hydro**philic** pathways in the membrane, so substances like H2O and ions can cross.
40
Some ion channels are \_\_\_\_\_, which means that they switch between open, closed, and intermediate states.
Some ion channels are **voltage-gated**, which means that they switch between open, closed, and intermediate states.
41
Carrier proteins bind to a specific solute (ex. glucose and amino acids) and transport it across the _____ bilayer. When performing the transport step, the carrier protein changes \_\_\_\_\_, allowing the solute to move from one side of the membrane to the other. Transport proteins are very selective about which solutes they will carry.
Carrier proteins bind to a specific solute (ex. glucose and amino acids) and transport it across the **lipid** bilayer. When performing the transport step, the carrier protein changes **shape**, allowing the solute to move from one side of the membrane to the other. Transport proteins are very selective about which solutes they will carry.
42
Osmosis [is] the simple passive diffusion of water across a membrane. Water always diffuses from an area of _____ solute concentration (\_\_\_\_\_ water concentration) to an area of _____ solute concentration (\_\_\_\_\_ water concentration).
Osmosis [is] the simple passive diffusion of water across a membrane. Water always diffuses from an area of **lower** solute concentration (**high** water concentration) to an area of **greater** solute concentration (**low** water concentration).
43
Does the following describe hypotonic, hypertonic, or isotonic conditions?
Solution (surrounding a cell) contains dissolved substances at a lower concentration than they are in the cell.
Hypotonic
44
Does the following describe hypotonic, hypertonic, or isotonic conditions?
Solution (surrounding a cell) contains dissolved substances at a higher concentration than they are in the cell.
Hypertonic
45
Does the following describe hypotonic, hypertonic, or isotonic conditions?
Concentration of water inside and outside cells is equal.
Isotonic
46
Does the following describe hypotonic, hypertonic, or isotonic conditions?
Solution (surrounding a cell) contains a higher concentration of water than in the cell.
Hypotonic
47
Does the following describe hypotonic, hypertonic, or isotonic conditions?
Solution (surrounding a cell) contains a lower concentration of water than in the cell.
Hypertonic
48
Active transport is the movement of substances across membranes _____ their concentration gradient using _____ (energy-dependent process).
Active transport is the movement of substances across membranes **against** their concentration gradient using **pumps** (energy-dependent process).
49
\_\_\_\_\_ active transport moves positively charged ions, such as H+, Ca2+, Na+, and K+ across the membrane. The concentration _____ that are established by these active transport pumps underline functions that are absolutely essential for cellular life.
**Primary** active transport moves positively charged ions, such as H+, Ca2+, Na+, and K+ across the membrane. The concentration **gradients** that are established by these active transport pumps underline functions that are absolutely essential for cellular life.
50
How many Na+ ions are pushed out of the cell and how many K+ ions are pushed into the cell simultaneously by a sodium-potassium pump?
Three Na+ are pushed out of the cell and two K+ ions are pushed into the cell simultaneously by a sodium-potassium pump.
51
\_\_\_\_\_ active transport uses the concentration gradient of an ion, established by a _____ pump, as its energy source.
**Secondary** active transport uses the concentration gradient of an ion, established by a **primary** pump, as its energy source.
52
What are the two mechanisms of secondary transport, and how do the differ?
Symport - a solute moves through the membrane channel in the same direction as the driving ion
Antiport - the driving ion moves through the membrane channel in one directioo, providing the energy for active transport of another molecule in the opposite direction
53
Sometimes cells need to move large quantities of materials into or out of their cytoplasm all at once. A process called _____ may accomplish this. As in active transport, all bulk-transport mechanisms use energy in the form of \_\_\_\_\_.
Sometimes cells need to move large quantities of materials into or out of their cytoplasm all at once. A process called **bulk transport** may accomplish this. As in active transport, all bulk-transport mechanisms use energy in the form of **ATP**.
54
Endocytosis is the form of bulk transport used to bring large amounts of material _____ the cell from the extracellular fluid.
Endocytosis is the form of bulk transport used to bring large amounts of material **into** the cell from the extracellular fluid.
55
What are the three forms of endocytosis?
Phagocytisis, pinocytosis, and receptor-assisted endocytosis.
56
[\_\_\_\_\_] only occurs in specialized cells, such as a single-celled amoeba or the bacteria eating white blood cells of our immune system (macrophages).
[**Phagocytosis**] only occurs in specialized cells, such as a single-celled amoeba or the bacteria eating white blood cells of our immune system (macrophages).
57
Phagocytosis begins when a solid particle comes in contact with the plasma membrane of a cell. The cell membrane send out fingerlike projections called _____ that surround and eventually enclose the particle in a vesicle that is within the cell's cytoplasm. Such a vesicle is called a \_\_\_\_\_.
Phagocytosis begins when a solid particle comes in contact with the plasma membrane of a cell. The cell membrane send out fingerlike projections called **pseudopods** that surround and eventually enclose the particle in a vesicle that is within the cell's cytoplasm. Such a vesicle is called a **phagocytotic vesicle**.
58
\_\_\_\_\_ containing digestive enzymes may fuse with the phagocytotic vesicle to digest the particles it contains. Nutrients formed by this digestion process move through the vesicle's membrane into the cell's cytoplasm.
**Lysosomes** containing digestive enzymes may fuse with the phagocytotic vesicle to digest the particles it contains. Nutrients formed by this digestion process move through the vesicle's membrane into the cell's cytoplasm.
59
[Pinocytosis] occurs in nearly all cell types. Pinocytosis occurs when a cell's plasma membrane engulfs a small drop of _____ fluid together with any _____ substances it might contain. This results in the formation of a pinocytotic vesicle.
[Pinocytosis] occurs in nearly all cell types. Pinocytosis occurs when a cell's plasma membrane engulfs a small drop of **extracellular** fluid together with any **dissolved** substances it might contain. This results in the formation of a pinocytotic vesicle.
60
What is the difference between phagocytosis and pinocytosis?
In phagocytosis, the cell takes in large solids. In pinocytosis, the cell takes in small amounts of extracellular fluid with dissolved substances into the cell.
61
[In receptor-mediated endocytosis,] specific molecules attach to membrane _____ that posse a uniquely shape projection or cavity that fits the shape of only one specific molecule.
[In receptor-mediated endocytosis,] specific molecules attach to membrane **receptors** that posse a uniquely shape projection or cavity that fits the shape of only one specific molecule.
62
Facilitated diffusion is specific. What does this mean?
Facilitated diffusion is specific in that specific transport proteins will carry certain polar or charged molecules but not others.
63
A red blood cell was placed in a beaker of solution. The cell immediately began to swell and finally burst. Explain what happened, referring to the cytosol of the cell and the solution in the beaker.
The cytosol of the cell was hypertonic to the solution in the beaker, which in turn was hypotonic to the cell. When the cell was placed in the beaker, water entered the cell by osmosis until the cell burst.
64
Distilled water is considered hypotonic to body cells. Explain.
Distilled water is hypotonic to body cells as it has a lower concentration of solutes than the cells do.
65
Compare the energy requirements of passive transport, primary active transport, and secondary active transport.
Passive transport requires no energy; active transport requires energy. Primary active transport expends energy directly through ATP hydrolysis. Secondary active transport relies on pre-established ion gradients for energy rather than direct hydrolysis of ATP.
66
What is meant by the term "concentration gradient"?
A concentration gradient is the gradual difference in concentration of a dissolved substance in a solution between regions.
67
Your biology study partner asks you a question about the concentration gradient of water. Is your study partner using the term "concentration gradient" correctly in reference to water? Explain why or why not.
No, “concentration gradient” is not being used correctly as water is usually the solvent, not the solute, and we do not refer to the concentration of the solvent.
68
How do size, polarity, and charge influence the ability of a substance to diffuse across a membrane?
The ability of a substance to diffuse across a membrane is hindered by larger size, polarity, and charge.
69
How does the concentration of a solute on the two sides of a membrane affect passive transport?
The concentration of the solute controls the direction of passive transport. The solute will diffuse across a membrane from the region of high concentration to the region of low concentration.
70
How does the concentration of a solute on the two sides of a membrane affect primary and secondary active transport?
Primary active transport is not dependent on solute concentration and actively works against the solute’s concentration gradient. Secondary active transport utilizes an ion concentration gradient, created by primary active transport processes, to move another solute against its own concentration gradient.
71
The transport of molecules across cellular membranes is important for the proper functioning of cells. Explain the role of transport across cell membranes in the proper functioning of red blood cells.
Red blood cells carry oxygen throughout the body, so the oxygen needs to get into and out of the blood cells.
72
The transport of molecules across cellular membranes is important for the proper functioning of cells. Explain the role of transport across cell membranes in the proper functioning of cells in the gut.
Cells in the gut absorb nutrients to fuel the body, so these solutes and molecules need to move in and out of cells.
73
The transport of molecules across cellular membranes is important for the proper functioning of cells. Explain the role of transport across cell membranes in the proper functioning of the release of hormones.
Hormones are released from cells in glands. Without transport across membranes, the hormones would not be released to help regulate the body.
