Medical Biochemistry - Demo Week 5

Front 1

Name two enzymes inhibited by insulin at the level of transcription.

Back 1

Glucose-6-phosphatase

PEP carboxykinase

Front 2

Name the insulin-dependent glucose transporter. Which cells express this transporter type?

Back 2

GLUT-4

Expressed in Muscle tissue (skeletal and cardiac) and adipose tissue

Front 3

Name the proteins responsible for the phenomenon that pancreatic β-cells release hardly any insulin at normal blood glucose level whereas at high blood glucose level they release much more insulin.

Back 3

Voltage gated Ca2+ channels

ATP gated K+ channels

GLUT-2 transporter

Front 4

What is the enzymatic activity of the ANF receptor?

Back 4

A catalytic receptor that stimulate intracellular guanylyl cyclase activity to convert GTP to cGMP.

Front 5

Describe briefly the hypothalamic effect of leptin leading to reduced food intake.

Back 5

Leptin acts on hypothalamus:

- Enhance release of alpha-MSH (melanocortin), which signals eat less.

- Inhibit the release of NPY, reducing eat-more-signals.

Front 6

Name 4 gastrointestinal hormones. How does ghrelin and PYY regulate food intake?

Back 6

Ghrellin

PPY

CCK

Amylin

- Ghrellin increases food intake

- PPY reduces food intake

Front 7

Via which enzyme and in what direction does insulin regulate the cholesterol synthesis?

Back 7

Insulin enhances cholesterol synthesis, through

HMG-CoA Reductase.

Front 8

Write the name and the structure of an allosteric inhibitor of carnitin-acyltransferase I.

Back 8

Front 9

Which hormone, in what direction and in which tissue regulates the activity of GLUT-4?

Back 9

Hormone: Insulin

Tissue: Muscle (skeletal and cardiac) and adipose tissue

Direction: Increases glucose uptake

(by releasing GLUT-4 vesicles to fuse with cell membrane, activating more transporters)

Front 10

In which organ, in response to what hormone and under what conditions is glucose formed

from glycogen?

Back 10

Organ: Liver

Condition: Low glucose level

Hormone: Glucagon

Front 11

Name the synthetic pathway that is stimulated by glucagon?

Back 11

Gluconeogenesis

Front 12

In what direction do sterols regulate the lipid synthesis in the adipose tissue?

Back 12

Sterols enhances lipid synthesis, and inhibits lipid breakdown.

Front 13

Name one of the allosteric regulator of glycogen-phosphorylase of liver!

Back 13

AMP

(High concentration activates glycogen phosphorylase b)

Front 14

Name the enzyme of fatty acid and cholesterol synthesis, respectively, which is regulated byinsulin? In what direction does insulin regulate these enzymes?

Back 14

Insulinenhances fatty acid/cholesterol synthesis.

HMG-CoAreductase

Citrate lyase

Front 15

Name an allosteric activator, an inhibitor, an activating and an inhibiting hormone thatregulate the activity of acetyl-CoA-carboxylase!

Back 15

Hormonal:

- Activator:Insulin indirectly?

- Inhibitor:Glucagon

Allosterically

- Activator:Citrate

- Inhibitor:Palmitoyl-CoA

Front 16

Write with structures the reaction that is inhibited by fructose-2,6-bisphosphate!

Back 16

Reaction catalyzed by fructose 1,6-bisphosphatase

Front 17

By which hormone and in what direction are glycogen synthesis and degradation regulated, respectively, when cAMP-dependent protein kinase is activated in the muscle?

Back 17

(cAMP-dependentprotein kinase=PKA)

Myocyte/Muscle: Epinephrine activatesPKA, which enhances glycogenDegredation, and inhibits glyogen synthesis.

Front 18

Write with structures the reaction catalyzed by tyrosine aminotransferase.

Back 18

Front 19

Write with structures the reaction catalyzed by p-hydroxyphenylpyruvate dioxygenase.

Back 19

Front 20

Write with structures the reaction catalyzed by homogentisate 1,2 dioxygenase.

Back 20

Front 21

Write with structures the reaction catalyzed by fumarylacetoacetase.

Back 21

Front 22

Write with structures the reaction catalyzed by tyrosine hydroxylase.

Back 22

Front 23

Write with structures the reaction catalyzed by phenylalanine hydroxylase.

Back 23

Front 24

Write with structures the reaction catalyzed by tryptophan hydroxylase.

Back 24