Transport

Question 1

What is the average circulatory time?

Answer 1

1 minute

Question 2

How many cells are reached in circulation?

Answer 2

10¹⁴ cells within minutes

Question 3

How many oxygen molecules does each haemoglobin molecule bind to?

Answer 3

4

Question 4

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

Answer 4

250 times stronger

Question 5

What percentage of CO in air leads to unconsciousness?

Answer 5

0.1%

Question 6

What compounds have similar characteristics to CO?

Answer 6

CN-

H2S

Question 7

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

Answer 7

Plasma carrier proteins

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

Question 8

What transports steroids?

Answer 8

Transcortin

Question 9

What transports thyroid hormones?

Answer 9

They bind to thyroxine-binding globin

Question 10

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

Answer 10

Hydrophobic

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

Question 11

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

Answer 11

Passive transport
Active transport
Facilitated transport

Question 12

What is passive transport?

Answer 12

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

Question 13

Does passive transport require energy?

Answer 13

No

Question 14

What is facilitated transport?

Answer 14

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

Question 15

Does facilitated transport require energy?

Answer 15

No

Question 16

What is active transport?

Answer 16

A protein pumps ions/molecules against a gradient

Question 17

Does active transport require energy?

Answer 17

Yes

Question 18

What types of molecules are mainly involved in passive transport?

Answer 18

Gases and small molecules

Question 19

What is passive transport driven by?

Answer 19

Entropy

Question 20

What are the 3 factors affecting diffusion rate?

Answer 20

Concentration
Hydrophobicity
Electrochemical gradients

Question 21

How does concentration affect diffusion rate?

Answer 21

The larger the concentration gradient, the faster the diffusion

Question 22

What are the three membrane transport proteins?

Answer 22

Channels
Transporters
Pumps

Question 23

What do channels do?

Answer 23

Transports ions and water down the gradient

Forms a “pore” through the membrane

Question 24

What do transporters do?

Answer 24

Transports small molecules or ions down the gradient

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

Question 25

Is there any energy used in a transporter? Why?

Answer 25

No | Transports down a gradient

Question 26

What do pumps do?

Answer 26

Transport ions or small molecules against the gradient

Question 27

Do pumps use energy? Why?

Answer 27

Yes | They break an equilibrium which needs energy to do

Question 28

What type of membrane transport protein does facilitated transport use?

Answer 28

Channels | Transporters

Question 29

What do most ion channels open in response to?

Answer 29

Specific signals | Eg. Voltage gated

Question 30

What forms a hydrophilic channel through the membrane?

Answer 30

Alpha-helices

Question 31

Is there any energy involved in a channel? Why?

Answer 31

No | Molecules and ions move down a gradient

Question 32

How do transporters work?

Answer 32

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

Question 33

What are the three types of transporter?

Answer 33

Uniporter Symporter Antiporter

Question 34

What does a uniporter do? eg?

Answer 34

Transports only one molecule down the gradient | glucose transport

Question 35

What does a symporter do? eg?

Answer 35

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

Question 36

What does an antiporter do? eg?

Answer 36

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

Question 37

What voltage membrane potential do nerve cells need?

Answer 37

-70mV

Question 38

How is membrane potential -70mV maintained?

Answer 38

Actively pumping positive ions to the outside

Question 39

What does the synthesis of ATP use?

Answer 39

Reverse ATP-pump

Question 40

What are the 4 types of ATP-powered pumps?

Answer 40

``` P-class Maintains membrane potential Aids in muscle relaxation Maintains low pH in stomach ```

Question 41

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

Answer 41

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

Question 42

What do secretory and endocytic pathways do?

Answer 42

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