Text C Biology 8.2 Transport Across Cell Membranes Flashcards
(106 cards)
1
Q
What structure controls most of the movement in and out of the cell?
A
The cell membrane
The cell membrane is selectively permeable, allowing certain substances to cross while restricting others.
2
Q
What is the term for the movement across membranes that is selective?
A
Selective transport
This process distinguishes between different molecules based on size, shape, and electric charge.
3
Q
What must the cell sometimes use to transport materials across the membrane?
A
Energy
Some molecules require energy for transport, while others do not.
This is called active transport.
4
Q
What is the term for the constant, random motion of particles?
A
Brownian motion
This motion occurs in liquids or air and is a key concept in the particle model of matter.
5
Q
Why does it take longer for a sugar cube to dissolve in iced tea than in hot tea?
A
Lower temperature reduces particle motion
In hot tea, particles move faster, facilitating quicker dissolution.
6
Q
What distinguishes the molecules that are allowed to cross the cell membrane?
A
Size, shape, and electric charge
These characteristics are crucial for selective transport.
7
Q
Fill in the blank: Movement across membranes without using energy is called _______.
A
passive transport
Passive transport allows molecules to move freely without energy expenditure.
8
Q
What is the net movement of particles in a concentration gradient?
A
Particles move toward areas of lower concentration.
9
Q
What happens when sugar is added to a cup of tea?
A
Sugar molecules spread out to give the tea a uniform sweetness.
10
Q
What is a concentration gradient?
A
The difference in concentration between two areas.
11
Q
What does it mean for molecules to reach a state of equilibrium?
A
Molecules are distributed evenly throughout the solution.
12
Q
True or False: Molecules stop moving once equilibrium is reached.
A
False
13
Q
What is the overall effect on the distribution of molecules after reaching equilibrium?
A
The net flow does not change.
14
Q
Fill in the blank: Molecules move down a concentration gradient similarly to a cyclist coasting downhill, receiving a _______.
A
free ride
15
Q
What are the solute and solvent in the example of sugar in tea?
A
Solute: sugar molecules; Solvent: water
16
Q
What is passive transport?
A
Movement across cell membranes without an input of energy
Passive transport includes diffusion, osmosis, and facilitated diffusion.
17
Q
What helps materials move across cell membranes?
A
Brownian motion and concentration gradients
These processes facilitate the passive movement of molecules.
18
Q
Define diffusion.
A
The net movement of particles from an area of high concentration to an area of low concentration
Diffusion occurs without energy expenditure by cells.
19
Q
How do very small particles move across cell membranes?
A
They can move between the phospholipid molecules from one side of the cell membrane to the other
This movement is a part of the diffusion process.
20
Q
What is an example of diffusion in cells?
A
Oxygen travels down a concentration gradient from the fluid surrounding cells into the cytoplasm
Cells consume oxygen, preventing equilibrium.
21
Q
What is osmosis?
A
The diffusion of water molecules across a membrane
Osmosis occurs from areas of higher water concentration to areas of lower concentration.
22
Q
What happens when water molecules move into and out of a cell at the same rate?
A
The water is in a state of equilibrium
Equilibrium means no net movement of water molecules.
23
Q
What is a hypotonic solution?
A
A solution that has a higher concentration of water molecules than the cell cytoplasm
In hypotonic solutions, water moves into the cell.
24
Q
What occurs in a hypertonic solution?
A
The solute concentration inside the cell is higher than that of the solution outside
Hypertonic solutions gain water.
25
What is isotonic solution?
Solutions that have the same concentration of solutes
## Footnote
At equilibrium, the cytoplasm and the solution outside the cell are isotonic.
26
Fill in the blank: The diffusion of water molecules across a membrane is called _______.
osmosis
27
Fill in the blank: A solution that loses water is called _______.
hypotonic
28
True or False: Cells expend energy to transport materials by diffusion.
False
## Footnote
Diffusion is a passive transport process.
29
What is the relationship between solute concentration and the movement of water in a hypotonic solution?
Higher concentration of water molecules outside the cell leads to water moving into the cell
## Footnote
This results in the cell swelling.
30
What is the definition of osmoregulation?
The process by which cells maintain water balance across the cell membrane
31
What happens to animal cells placed in distilled water?
They swell and may eventually burst
32
What occurs to animal cells placed in relatively salty water?
They shrivel, a process called plasmolysis
33
What happens to plant cells in a hypertonic solution?
They shrivel as the central vacuole loses water
34
Why is osmoregulation important for cells?
Maintaining water balance is vital for cell survival
35
What can excessive water intake do to a cell?
It can kill the cell by causing it to burst
36
What is turgor pressure?
An internal force in plant cells that keeps structures firm due to water uptake
37
What happens to cells in strong salt water?
Water diffuses out, causing the cells to shrink and possibly die
38
What substances can diffuse through the cell membrane?
Water, oxygen, and carbon dioxide
39
Why can't glucose molecules pass through the cell membrane by simple diffusion?
They are too big to squeeze between the phospholipid molecules
40
What prevents charged ions from crossing the cell membrane by simple diffusion?
Their charge causes them to be repelled by the hydrophobic tails of membrane phospholipids
41
Fill in the blank: The solution outside the cells is _______ to the cytoplasm when placed in salt water.
hypertonic
42
True or False: Plant cells can withstand pressure from water uptake due to their cell wall.
True
43
What happens to plant structures when turgor pressure is maintained?
They remain firm
44
What is the effect of drinking salt water for humans?
It can lead to dehydration and death within days
45
What are transport proteins?
Membrane proteins that help move materials across the membrane
## Footnote
Transport proteins are essential for the movement of substances that cannot cross the membrane by simple diffusion.
46
What is facilitated diffusion?
The use of transport proteins to aid the diffusion of particles across the cell membrane
## Footnote
Facilitated diffusion occurs down a concentration gradient and is a type of passive transport.
47
How do transport proteins recognize atoms or molecules?
By their shape, size, and electrical charge
## Footnote
Transport proteins are highly selective, similar to how a key fits only a certain lock.
48
What are the two types of transport proteins?
* Carrier proteins
* Channel proteins
## Footnote
Each type serves a different function in transporting substances across the cell membrane.
49
What does a carrier protein do?
Facilitates the diffusion of glucose across the cell membrane
## Footnote
Carrier proteins change shape to allow certain molecules to cross the membrane.
50
What is the role of channel proteins?
Form tunnel-like pores in the membrane filled with water, allowing charged ions in and out of the cell
## Footnote
Channel proteins provide water-filled passages for small dissolved ions.
51
What is active transport?
The process of using energy to transport materials across membranes against a concentration gradient
## Footnote
Active transport is necessary when cells need to move substances from areas of lower concentration to higher concentration.
52
When do cells use active transport?
When they have to work against a concentration gradient
## Footnote
This often occurs when root cells require minerals from the soil.
53
What condition is associated with faulty channel proteins?
Cystic fibrosis
## Footnote
This genetic disorder leads to an imbalance of ions inside and outside cells, causing thick and sticky mucus.
54
How does cystic fibrosis affect the lungs?
Thick mucus interferes with breathing and traps disease-causing bacteria
## Footnote
The abnormal mucus layer can lead to serious respiratory issues.
55
Fill in the blank: Facilitated diffusion always occurs down a _______.
concentration gradient
## Footnote
This principle is fundamental to understanding how substances move across cell membranes.
56
What energy source do cells use for active transport?
Energy from ATP
## Footnote
ATP is the primary energy currency of the cell, used for various cellular processes including active transport.
57
What percentage of energy do cells use for active transport even when resting?
Up to 40 percent
## Footnote
Many specialized cells, like kidney cells, use even more energy for active transport.
58
What percentage of energy do kidney cells use for active transport?
Up to 90 percent
## Footnote
Kidney cells filter blood and require significant energy for active transport.
59
What is the role of active transport in plant root cells?
To take in minerals from the surrounding soil
## Footnote
Root cells use carrier molecules and energy to move additional minerals into the cells.
60
How do active and passive transport differ?
Active transport requires energy; passive transport does not
## Footnote
Both mechanisms allow materials to cross the cell membrane.
61
What are the common topics to compare in a poster illustrating active and passive transport?
* Cell membrane structures
* Type of materials transported
* Direction of transport
* Equilibrium
* Carrier molecules
* Consumption of energy
62
What is the main function of active transport?
Helps maintain an internal environment different from the external environment
## Footnote
This is crucial for concentrating nutrients and removing toxic waste.
63
What are the two processes by which cells can transport materials that cannot be moved by passive or active transport?
Endocytosis and Exocytosis
## Footnote
These processes involve the cell membrane forming pockets around materials.
64
What is endocytosis?
A process where the cell membrane forms a pocket around material to be transported
## Footnote
The membrane folds in and encloses the item in a sphere.
65
What happens to the sphere formed during endocytosis?
It typically pinches off as a vesicle or forms a vacuole
## Footnote
Vesicles transport contents within the cell; vacuoles act as storage sites.
66
What is phagocytosis?
A type of endocytosis where cells take in large particles or other cells
## Footnote
This process is often referred to as 'cell eating.'
67
What is pinocytosis?
A type of endocytosis where cells take in droplets of fluid
## Footnote
This process is often referred to as 'cell drinking.'
68
What type of molecules cannot dissolve in water and cannot diffuse across membranes?
Cholesterol
## Footnote
Large protein molecules and bacterial cells are also too large to cross membranes.
69
What is the purpose of active transport in cells?
To concentrate nutrients and remove toxic waste
## Footnote
This process is essential for cell growth and activities.
70
What is phagocytosis?
A process used by cells to ingest food or other solids
## Footnote
Involves the cell membrane surrounding a particle, fusing, and forming a vesicle
71
What is pinocytosis?
A process where the cell membrane surrounds droplets of fluid, forming a vesicle
## Footnote
Involves the membrane pinching off to take in fluid
72
What is exocytosis?
The process used to dispose of wastes or secrete cell products
## Footnote
Involves the vesicle membrane fusing with the cell membrane to release contents
73
What role do membrane proteins play in endocytosis?
They assist in the process by acting as receptors that detect specific compounds
## Footnote
Receptors bind items for transport, triggering endocytosis
74
What is receptor-mediated endocytosis?
A process where cells take in molecules like cholesterol by binding to receptors
## Footnote
This method allows specific transport of certain molecules into the cell
75
How does HIV enter cells?
By binding to receptors specialized for transport of other molecules, triggering endocytosis
## Footnote
HIV tricks the cell into transporting it inside
76
What are the main types of cell transport?
* Diffusion
* Osmosis
* Facilitated diffusion
* Active transport
* Endocytosis
* Exocytosis
## Footnote
These processes allow materials to be transported in and out of the cell
77
What do the prefixes 'endo-' and 'exo-' mean?
'Endo-' means inside, and 'exo-' means outside
## Footnote
They relate to endocytosis (bringing substances in) and exocytosis (expelling substances out)
78
Fill in the blank: _______ is the reverse of endocytosis.
Exocytosis
79
What happens to the membrane during phagocytosis?
The membrane surrounds the particle and fuses to form a vesicle
## Footnote
This vesicle then enters the cytoplasm
80
What is reverse osmosis used for?
To purify water by filtering it through an artificial membrane with very fine pores
## Footnote
Reverse osmosis filtration systems are commonly used in Canada to purify drinking water.
81
How does reverse osmosis work?
Water is forced through a semi-permeable membrane, allowing water to pass but blocking larger particles such as bacteria and salts
## Footnote
Pressure is applied to push contaminated water through the membrane.
82
What substances can pass through the reverse osmosis membrane?
Water can pass through, but larger particles like bacteria, salts, and other dissolved molecules cannot
## Footnote
This selective permeability is crucial for effective water purification.
83
What role do kidneys play in the body?
They filter blood, regulate solute and water content, and eliminate wastes
## Footnote
They also retain valuable substances like proteins, glucose, and certain ions.
84
What happens when kidneys are damaged?
They do not filter blood properly, leading to toxic accumulation of wastes
## Footnote
Patients may require a kidney transplant or dialysis.
85
What is kidney dialysis?
A process where a patient's blood is filtered through an artificial membrane to remove wastes
## Footnote
Dialysis tubing is immersed in a salt solution to facilitate this process.
86
What is the function of the dialysis tubing in kidney dialysis?
It allows small dissolved waste molecules to diffuse out of the blood while retaining large proteins and blood cells
## Footnote
This helps cleanse the blood without losing essential components.
87
What is a controlled delivery of medications?
A method of providing medications at constant levels using semi-permeable membranes
## Footnote
This is often achieved through transdermal patches.
88
What is the advantage of using semi-permeable membranes in medication delivery?
They allow drugs to diffuse out at a slow, constant rate
## Footnote
This helps maintain stable medication levels in the body.
89
What types of medications are effective for transdermal patches?
* Nicotine for quitting smoking
* Motion sickness drugs
* Pain reducers
* Hormones for correcting imbalances
## Footnote
These medications must easily diffuse through the skin.
90
Fill in the blank: The process of forcing contaminated water through a membrane to purify it is called _______.
reverse osmosis
91
True or False: Reverse osmosis can remove large particles such as bacteria and salts from water.
True
92
What is the purpose of the dialysate in kidney dialysis?
To provide a solution that allows waste molecules to diffuse out of the blood without losing salts and water
## Footnote
The dialysate has a concentration similar to blood but does not contain wastes.
93
What are liposomes?
Artificial vesicles that transport medications safely from one part of the body to another
## Footnote
Liposomes are used to deliver anti-cancer medications to tumors in some cancer patients.
94
What controls the movement of molecules in and out of the cell?
Cell membranes
## Footnote
Cell membranes regulate the passage of substances, maintaining homeostasis.
95
What is passive transport?
Movement of molecules across the membrane without expending energy
## Footnote
Includes processes like diffusion, osmosis, and facilitated diffusion.
96
What types of transport are included in passive transport?
* Diffusion
* Osmosis
* Facilitated diffusion
## Footnote
Passive transport does not require energy input from the cell.
97
What is active transport?
Movement of molecules against a concentration gradient that requires energy
## Footnote
Active transport is crucial when moving substances from areas of low concentration to areas of high concentration.
98
What processes move large molecules in and out of the cell?
* Endocytosis
* Exocytosis
## Footnote
These processes involve the formation of vesicles to transport large molecules.
99
Define diffusion.
The movement of molecules from an area of higher concentration to an area of lower concentration
## Footnote
Diffusion occurs until equilibrium is reached.
100
How does osmosis differ from diffusion?
Osmosis specifically refers to the movement of water across a semi-permeable membrane
## Footnote
Diffusion can involve any type of molecule, while osmosis is limited to water.
101
What makes osmosis and diffusion similar?
Both processes involve the movement of molecules down their concentration gradient
## Footnote
They are both passive processes that do not require energy.
102
Why is facilitated diffusion considered passive transport?
It does not require energy despite using membrane proteins for molecule transport
## Footnote
The molecules still move down their concentration gradient.
103
List four applications of semi-permeable membranes.
* Medical applications
* Industrial applications
* Water purification
* Food processing
## Footnote
Semi-permeable membranes are crucial in various fields for selective permeability.
104
What would happen to Paramecium without a contractile vacuole?
It would accumulate excess water and potentially burst
## Footnote
The contractile vacuole helps maintain osmotic balance in the organism.
105
What is the predicted effect of placing Paramecium in salt water?
It would likely lose water and shrivel due to osmosis
## Footnote
Salt water creates a hypertonic environment for the Paramecium.
106
How does active transport affect equilibrium across the cell membrane?
It moves particles against a concentration gradient, preventing equilibrium
## Footnote
This allows the cell to maintain different concentrations of substances on either side of the membrane.
