Hormone types and the intracellular signalling pathways Part 1

Question 1

What the general pathway for homeostatic control

Answer 1

Signal-> reception-> transduction-> response
Signal amplified between reception and transduction
Feedback mechanism throughout

Question 2

What are the principles of metabolic regulation

Answer 2

The flow of metabolites through pathways must be regulated to maintain homeostasis.
Homeostasis occurs when metabolite concentrations are at a steady state.
Following perturbation, a new steady state is achieved.
Sometimes the levels of required metabolites must be altered very rapidly

Regulation of only one or two key metabolic steps regulates the rate of the entire pathway.

Question 3

What is true about rates to concentration nearer to Km

Answer 3

Rates are more sensitive to concentration at conc near or below Km
At low substrate conc rate changes quickly

Question 4

What are the different glucose transport proteins names?

Answer 4

GLUT1
GLUT2
GLUT3
GLUT4

Question 5

Where can GLUT1 be found?

Answer 5

RBC and other tissues

Question 6

Where can GLUT2 be found?

Answer 6

Liver pancreas

Question 7

Where can GLUT3 be found?

Answer 7

Brain

Question 8

Where can GLUT4 be found?

Answer 8

Muscle adipose tissue

Question 9

What is the Km of GLUT1?

Answer 9

3mM

Question 10

What is the Km of GLUT2?

Answer 10

17mM

Question 11

What is the Km of GLUT3?

Answer 11

1.4mM

Question 12

What is the Km of GLUT4?

Answer 12

5mM

Question 13

How does GLUT2 Km benefit its function?

Answer 13

high Km means that if you look at graph and find rate of glucose uptake at normal glucose concentration, rate is rapidly increasing. Important as liver and pancreas can act quickly on glucose and release right hormones(diabetes) etc

Question 14

How doesGLUT3 Km benefit its function?

Answer 14

low Km means that if you look at graph and find rate of glucose uptake at normal glucose concentration, rate is constant and this is also true at low Km. Important- brain recieves steasy supply of glucose despite low conc of glucose
Working near Vmax

Question 15

What happens to glucose once it enters the cell and why is this important?

Answer 15

Phosphorylated and converted to glucose-6-phosphate by hexokinase/ glucokinase
-No longer substrate for GLUT transporter protein so cant leave the cell
Maintain conc gradient for free glucose molecules- always a low level of free glucose inside cell as always converted
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