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MED 103- BIOLOGY I > 25. ACTIVE TRANSPORT > Flashcards

25. ACTIVE TRANSPORT Flashcards

1
Q
  1. What are two characteristics of Active Transport?
A
  • they move substances against their concentration gradient

(they move from a place of low concentration to a place of high concentration)

  • they require energy to do this
    (usually in the form of ATP)
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2
Q
  1. What does Active Transport allow the cells to maintain?
A
  • they can maintain their concentration gradients
  • these differ from their surroundings
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3
Q
  1. What structure performs active transport?
A
  • ion pumps
  • these are specific membrane proteins
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4
Q
  1. What is one form of an ion pump?
A
  • the sodium-potassium pump
    (Na+/K+)
  • it is a type of active transport system
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5
Q
  1. What do ion pumps do?
A
  • they move substances across a membrane
  • this movement is against their concentration
  • energy for this work is usually supplied by the ATP
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6
Q
  1. What is membrane potential?
A
  • it is the voltage difference across a membrane
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7
Q
  1. What is voltage created by?
A
  • it is a result of the differences in the distribution of the positive and the negative ions
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8
Q
  1. Which structure of the cells is negatively charged compared to the outside?
A
  • the cytoplasm of the cells
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9
Q
  1. What does the membrane potential act as?
A
  • it acts as a battery
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10
Q
  1. What does the membrane potential favour?
A
  • it favours the passive transport of cations into the cell
  • these are the positive ions
  • it favours the passive transport of anions out of the cell
  • these are the negative ions
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11
Q
  1. Which pump contributes to the creation and the maintenance of the membrane potential?
A
  • the Na+/K+ pump
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12
Q
  1. How does the Na+/K+ pump contribute to the creation and the maintenance of the membrane potential?
A
  • it transports 3 Na+ ions out of the cell
  • it transports 2 K+ ions into the cell
  • there is a net transfer of one + charge out
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13
Q
  1. Provide a definition for the Electrochemical gradient?
A
  • this is the combination of two forces
  • they drive the diffusion of an ion
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14
Q
  1. What are the two forces of the electrochemical gradient?
A
  • a chemical force
  • an electrical force
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15
Q
  1. What is a chemical force?
A
  • it is the ion’s concentration gradient
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16
Q
  1. What is an electrical force?
A
  • it is the effect of the membrane potential on the ion’s movement
  • this is the ions charge
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17
Q
  1. Provide a description for label one.
A
  • the cytoplasmic Na+ binds to the sodium-potassium pump
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18
Q
  1. Provide a description for label two.
A
  • the Na + binding stimulates the phosphorylation by ATP hydrolysis

PHOSPHORYLATION= the process in which a phosphate group is added to a molecule

(EG: sugar or a protein)

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19
Q
  1. Provide a description for label three.
A
  • the Phosphorylation causes the protein to change its conformation/structure
  • this expels the Na+ to the outside
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20
Q
  1. Provide a description for label four.
A
  • the extracellular K+ binds to the protein
  • this triggers the release of the Phosphate group
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21
Q
  1. Provide a description for label five.
A
  • the loss of the phosphate restores the protein’s original conformation/structure
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22
Q
  1. Provide a description for label six.
A
  • the K+ is released
  • the Na+ sites are receptive again
  • the cycle repeats
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23
Q
  1. What are Electrogenic pumps?
A
  • they transport the proteins
  • these proteins generate the voltage across a membrane
  • this creates the membrane potential
  • they require a source of energy to do this
    (ATP Hydrolysis)
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24
Q
  1. Which pump is present in animals?
A
  • the Na+/K+ (sodium-potassium) pump
25
Q
  1. What pump is present in plants, fungi and bacteria?
A
  • the H+ (proton) pump
26
Q
  1. What is Cotransport?
A
  • this is the coupled transport of substances
  • it is done by a membrane protein (cotransporter)
27
Q
  1. What spending is active transport driven by?
A
  • it is driven by the indirect spending of energy
  • this is when the concentration gradient of one substance indirectly drives the active transport of another substance
  • the passive transport of one substance indirectly drives the active transport of another
28
Q
  1. Name one example of Cotransport?
A
  • the passive transport of the H+ to the inside of the cell
  • this is done by the diffusion that is coupled with the active
    transport of sucrose
29
Q
  1. Explain how the transport of H+ to the inside of the cell occurs as a result of Cotransport.
A

ACTIVE TRANSPORT:
- the proton pump maintains a higher H+ outside the cell than inside the cell
- this leads to ATP being spent

PASSIVE TRANSPORT:
- the H+ gradient is stored as potential energy
- the sucrose H+ cotransporter drives the movement of the sucrose
- it does this by bringing down their gradient

30
Q
  1. How do small molecules and water enter or exit the cell?
A
  • they do this through the lipid bilayer
  • they can also do this by transport proteins
31
Q
  1. What does Bulk transport consist of?
A
  • it consists of the movement of large macromolecules across the plasma membrane
  • this is done through the usage of transport vesicles
32
Q
  1. What causes Bulk Transport?
A
  • endocytosis
  • exocytosis
33
Q
  1. What can be said about Active transport processes?
A
  • they require energy
34
Q
  1. What is Exocytosis?
A
  • it is the transport of macromolecules
  • these macromolecules are packaged in vesicles
  • they are transported from the inside of the cell to the outside of the cell
  • this is done via the fusion of the transport vesicles with the plasma membrane
35
Q
  1. Which cells use exocytosis to export their products?
A
  • secretory cells
36
Q
  1. What is an example of Exocytosis?
A
  • the pancreatic cells produce insulin
  • they secrete it to the extracellular fluid
  • this is done by exocytosis
37
Q
  1. What is Endocytosis?
A
  • it is the transport of macromolecules
  • they are transported from the outside of the cell to the inside of the cell
  • this is a result of the formation of transport vesicles
  • these transport vesicles are an extension/projection of the plasma membrane
  • to the inside of the cell
38
Q
  1. What happens during endocytosis?
A
  • the cell takes in the macromolecules
  • it does this by forming new vesicles from the plasma membrane
39
Q
  1. What are the three types of endocytosis?
A
  1. Pinocytosis
  2. Phagocytosis
  3. Receptor-Mediated Endocytosis
40
Q
  1. What is another name for Pinocytosis?
A
  • Cellular Drinking
41
Q
  1. What is Pinocytosis?
A
  • it is the intake of liquid or soluble material by the cell
  • soluble molecules are taken up
  • this happens when the extracellular fluid is engulfed into
    tiny vesicles
42
Q
  1. What is another name for Phagocytosis?
A
  • Cellular Eating
43
Q
  1. What is Phagocytosis?
A
  • it is the intake of solid and soluble materials by the cell
  • it is the ingestion of whole cells
    (EG: microorganisms)
44
Q
  1. What happens during Phagocytosis?
A
  • the cell engulfs a solid particle
    (such as a macromolecule or a microorganism)
  • into a vacuole
    (such as a phagosome or a food vacuole)
  • the vacuole then fuses with a lysosome
  • this allows particles to be digested
  • a phagolysosome is formed
45
Q
  1. What are Phagocytes?
A
  • they are specialised immune cells
  • they are able to engulf microorganisms
  • this is done through the help of the digestion by
    lysosomes

-the cell membrane receptors then recognise the microorganism

46
Q
  1. What is an example of a Phagocyte?
A
  • macrophages
47
Q
  1. Where do Pseudopodia form?
A
  • they form around the microorganism
  • they enclose the microorganism into a vesicle
    (they enclose it into a phagosome)
48
Q
  1. What is Receptor-Mediated Endocytosis?
A
  • it is a special type of endocytosis
  • it is the intake of specific molecules that are selected by a
    receptor
  • it is the entrance of specific extracellular compounds into the cell
  • the receptors select these specific compounds
49
Q
  1. What happens during Receptor-Binding Endocytosis?
A
  • the ligands bind to the receptors
  • this triggers vesicle formation
50
Q
  1. What is a ligand?
A
  • it is any molecule that bonds specifically to a receptor molecule
51
Q
  1. What is an example of Receptor-Mediated Endocytosis?
A
  • the cholesterol uptake done by hepatocytes
52
Q
  1. What is Cholesterol?
A
  • it is a type of lipid
  • it is hydrophobic
  • it cannot circulate around the blood by itself
  • it can circulate in blood when it is bound to lipoproteins
  • these can be either low density lipoproteins (LDL)
  • or high density lipoproteins (HDL)
53
Q
  1. How are Lipoproteins recognised?
A
  • they are recognised by their receptor
  • this is found on the plasma membrane of the liver cells
54
Q
  1. What process allows Cholesterol to be released into the liver cells?
A
  • the cell takes in the lipoproteins
    (cholesterol vesicles)
  • cholesterol is then released into the liver cell
55
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
56
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
57
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes
58
Q
  1. Read through this summary.
    Does everything make sense?
A
  • yes

MED 103- BIOLOGY I (53 decks)

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