Transport Flashcards

1
Q

The cytoplasmic membrane has a ___ that prevents leakage and functions as a ___ for nutrient transport in and out

A

permeability barrier/gateway

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2
Q

Why does water transport freely across the membrane?

A

it is small and weakly polar

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3
Q

___ PRO transport those molecules that the membrane isn’t permeable to

A

integral

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4
Q

Describe facilitated diffusion

A

transports solutes down a gradient, for uncharged substrates the gradient alone determines the direction but for charged particles the charge and gradient have an effect

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5
Q

Describe active transport

A

transports solutes against a gradient

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6
Q

Transport systems are ___; the rate of update becomes ___ and increase of substrate ___ increase rate

A

saturable/maximal/doesn’t

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7
Q

Transport systems are ___; they transport ___ molecules or molecules ___

A

specific/single/of a series

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8
Q

True or false: biosynthesis is not very regulated by the cell

A

false, it is highly regulated

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9
Q

In unicellular organisms nutrients are usually acquired via ___, in multicellular they’re usually acquired via ___ or ___

A

active transport/diffusion/facilitated diffusion

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10
Q

What are the types of facilitated diffusion? Include a brief description

A
  1. channel-mediated: specificity is low, can be closed by cell (gated)
  2. carrier-mediated: substrate binds to one side of the membrane and induces a conformational change, the substrate is then released on the other side, much more specific and required no energy
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11
Q

Types of transporters: ___ (one molecule), ___ (one in, another out), ___ (two in the same direction)

A

uniporter/antiporter/symporter

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12
Q

Describe pmf-dependant transport

A

in bacteria and archaea, under conditions where respiration is possible a pmf is generated, if respiration is not possible ATPases can create a pmf, some sym and antiporters can use the pmf to generate energy

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13
Q

What are some pmf transporters that use H+ gradient?

A

cation uniporter, proton symporter, anion symporter, proton-X symporter

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14
Q

What are some pmf transporters that use Na+ gradient?

A

Na-anion symporter, Na-X symporter

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15
Q

Where is the Na+ generated pmf common?

A

marine environments

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16
Q

What are the three components of ABS transporters?

A
  1. membrane-spanning PRO (active transport carrier)
  2. ATP-hydrolyzing PRO (provides energy for active transport)
  3. substrate-specific binding PRO (has high affinity for specific substrate)
17
Q

How do ABC transporters function?

A

binding PRO binds to substrate and transfers it to the transporter where it is actively transported using ATP generated

18
Q

Where is the binding PRO (for ABC transporter) in G+ and G- organisms?

A

G+: anchored in the cytoplasmic membrane

G-: free in periplasm

19
Q

What are the rates of permeability of glucose and glycerol?

A

glucose: 0.001 (fair/poor)
glycerol: 0.1 (good)

20
Q

Describe group translocation?

A

substrate is modified as it passes through transporter across the membrane

21
Q

What is an example of group translocation?

A

PEP-dependant sugar phosphotransferase system, used by bacteria to transport common monosaccharides

22
Q

How is transport done in unicellular eukaryotes?

A

pmf is generated inside the mitochondria usually but in this case it needs to be generated in the cytoplasmic membrane; proton translocating ATPase in the cytoplasmic membrane used ATP to pump out protons which generates a pmf at cytoplasmic membrane level which is used to power symporters in the cytoplasmic membrane

23
Q

How many H+ do F-type ATPase and P-type ATPase pump out during generating of the cytoplasmic membrane pmf?

A

F: 3
P: 1

24
Q

What are the types of endocytosis with a brief description:

A
  • phagocytosis: large, solid particles enter via food vacuoles
  • pinocytosis: small fluid particles enter via vesicle
  • receptor-mediated: coated vesicle with coat PRO from a pit coated with receptors