Physiology Ex 1 - Ion Gradients and Transport Flashcards Preview

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Flashcards in Physiology Ex 1 - Ion Gradients and Transport Deck (31)
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2

How long do each of the 1 billion ATP molecules in the cell last?

less than one minute and 70% is used to pump Na+/K+

3

What is ADP to ATP conversion used for?

Glycolysis

Oxidative metabolism

4

What is ATP to ADP conversion used for?

Membrane transport

Anabolism

Catabolism

Mechanical work

Etc

5

What is required for the efficient production of ATP by cells?

A hydrogen ion gradient across the mitochondrial inner membrane

6

ATP synthase uses the energy of hydrogen ions diffusing down the gradient to produce?

ATP

7

Electron Transport Chain proteins use energy derived from metabolism to?

Pump hydrogen ions across the inner mitochondrial membrane

8

What does the metabolic poison 2,4-Dinitrophenol (DNP) do?

Uncouples oxidative phosphorylation (inhibits ATP production) by acting as a proton ionophore carrying protons across the mitochondrial membrane and decreasing the proton gradient.

9

Why was DNP discontinued from use as a diet pill in the 1930's?

Because of the risk of fatal hyperthermia and development of cataracts

10

What does the metabolic poison Sodium Azide do?

Inhibits cytochrome oxidase by binding irreversibly to the heme cofactor (similar to cyanide poisoning). It affects organs that undergo high rates of repiration, such as the heart and brain. It inhibits growth of bacteria and fungi and is an airbag explosive.

11

What types of transport down a concetration gradient do not require added energy?

Simple diffusion

Facilitated diffusion (vmax)

12

What types of transport down a concetration gradient require added energy?

  • Active transport - Na/K ATPase, Ca ATPase, P-glycoprotein
  • Secondary active transport
  • Endocytosis and Exocitosis

13

Which types of molecules can diffuse across the membrane without a carrier?

Small lipid soluble molecules

14

Which molecules require a carrier or channel to diffuse across the membrane?

Hydrophilic molecules

15

Which are the membrane proteins that enable or facilitate passage of molecules across the membrane?

Channel proteins

Carrier proteins (passive, active)

16

How does Vmad limit the rate of transport (or diffusion)

Facilitated diffusion is driven by the concentration gradient across the membrane but limited by the number and function of the transporters

17

Does transporter-mediated diffusion require energy(net diffusion down a concentration gradient)?

No, however the rate of diffusion is NOT exclusively concentration-dependent unlike simple diffusion - the max rate of transport (Vmax) is related to the number of carrier molecules in the membrane and the speed with which the transporter protein can transport the molecule.

18

What is the main use of facilitated diffusion?

To transport glucose and most amino acids into cells

19

What is the specificity of the channel (channel proteins) determined by?

The size of the passageway and the charge of properties of the amino acids that make up the passageway

20

What causes the net movement through a channel (channel proteins)?

An electrochemical gradient

21

What are aquaporins?

Water channels

22

Name some ion channels

K+

Na+

Ca++

Cl-

monovalent

divalent

etc

23

Who discovered aquaporins?

Peter Agre (2003)

24

Which channels are always open?

Pores

Leak channels

25

Which channels are gated?

Gated channel

26

What are the types of gated channels?

  • Ligand-gated channel (triggered by binding of specific molecules to the channel)
  • Phosphorylation-gated channels (function altered by phosphorylation/dephosphorylation)
  • Voltage-gated channels (triggered by change in membrane potential)
  • Mechanically-gated channels (triggered by mechanical stress to membrane)

27

What type of gated channel are Nicotinic Cholinergic receptors?

Ligand-gated ion channels. 2 acetylcoline binding sites-binding of Ach opens the channel and allows Na+ ions to cross the membrane

28

What are carrier proteins?

Membrane proteins that transport molecules in one or both directions

29

Some molecules are transported by both carriers and channels. T/F?

True

30

Oxygen enters cells by

Simple diffusion

31

Sodium ions enter cells by

Primary active transport