Transport Flashcards

1
Q

What is the average circulatory time?

A

1 minute

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2
Q

How many cells are reached in circulation?

A

10¹⁴ cells within minutes

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3
Q

How many oxygen molecules does each haemoglobin molecule bind to?

A

4

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4
Q

How many times stronger does CO bind to haemoglobin compared to O2?

A

250 times stronger

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5
Q

What percentage of CO in air leads to unconsciousness?

A

0.1%

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6
Q

What compounds have similar characteristics to CO?

A

CN-

H2S

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7
Q

What are steroids and thyroids carried through the blood by? Why?

A

Plasma carrier proteins

They are very non-polar and don’t dissolve in the blood plasma

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8
Q

What transports steroids?

A

Transcortin

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9
Q

What transports thyroid hormones?

A

They bind to thyroxine-binding globin

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10
Q

What type of core does the cell membrane have? What does this mean?

A

Hydrophobic

Prevents ions, charged molecules, polar molecules and peptides from passing through

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11
Q

What are the three ways molecules can pass through the membrane?

A

Passive transport
Active transport
Facilitated transport

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12
Q

What is passive transport?

A

The compound diffuses spontaneously through the membrane from high to low concentration

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13
Q

Does passive transport require energy?

A

No

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14
Q

What is facilitated transport?

A

A protein helps transport ions/molecules from high to low concentration

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15
Q

Does facilitated transport require energy?

A

No

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16
Q

What is active transport?

A

A protein pumps ions/molecules against a gradient

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17
Q

Does active transport require energy?

A

Yes

18
Q

What types of molecules are mainly involved in passive transport?

A

Gases and small molecules

19
Q

What is passive transport driven by?

A

Entropy

20
Q

What are the 3 factors affecting diffusion rate?

A

Concentration
Hydrophobicity
Electrochemical gradients

21
Q

How does concentration affect diffusion rate?

A

The larger the concentration gradient, the faster the diffusion

22
Q

What are the three membrane transport proteins?

A

Channels
Transporters
Pumps

23
Q

What do channels do?

A

Transports ions and water down the gradient

Forms a “pore” through the membrane

24
Q

What do transporters do?

A

Transports small molecules or ions down the gradient

Binds to the molecule and “moves” it across the membrane

25
Q

Is there any energy used in a transporter? Why?

A

No

Transports down a gradient

26
Q

What do pumps do?

A

Transport ions or small molecules against the gradient

27
Q

Do pumps use energy? Why?

A

Yes

They break an equilibrium which needs energy to do

28
Q

What type of membrane transport protein does facilitated transport use?

A

Channels

Transporters

29
Q

What do most ion channels open in response to?

A

Specific signals

Eg. Voltage gated

30
Q

What forms a hydrophilic channel through the membrane?

A

Alpha-helices

31
Q

Is there any energy involved in a channel? Why?

A

No

Molecules and ions move down a gradient

32
Q

How do transporters work?

A

The molecule/ion binds to the transporter from the outside which causes a conformational change and causes the transporter to open the other side, releasing the molecule/ion

33
Q

What are the three types of transporter?

A

Uniporter
Symporter
Antiporter

34
Q

What does a uniporter do? eg?

A

Transports only one molecule down the gradient

glucose transport

35
Q

What does a symporter do? eg?

A

Transports two molecules down the gradient in the same direction
Glucose/Na+ transport

36
Q

What does an antiporter do? eg?

A

Transports two molecules down the gradient in opposite directions
Na+/H+ transport

37
Q

What voltage membrane potential do nerve cells need?

A

-70mV

38
Q

How is membrane potential -70mV maintained?

A

Actively pumping positive ions to the outside

39
Q

What does the synthesis of ATP use?

A

Reverse ATP-pump

40
Q

What are the 4 types of ATP-powered pumps?

A
P-class
Maintains membrane potential 
Aids in muscle relaxation 
Maintains low pH in stomach
41
Q

What are the steps of the P-Type ATP powered pump?

A
Ca2+ and ATP binds 
Phosphorylation 
Conformation change where the channel changes direction 
Ca2+ is released 
Dephosphorylation 
Conformation change
42
Q

What do secretory and endocytic pathways do?

A

Move large molecules or large amounts of molecules across the cell membrane