Disorders & Some Syllabus Companion Questions

Question 1

Symptoms:
- microcephaly
- ID
- seizures
- unusual odor
- eczema

Answer 1

Classical PKU

Question 2

What is the enzyme deficiency related to PKU?

Answer 2

phenylalanine hydroxylase

Question 3

What are the treatment options for PKU?

Answer 3

1. Phe restriction
2. Tyr supplementation
3. Sepoterin (BH₄ analogue)
4. Injectable enzyme (Pegvallase)
5. probiotic
6. gene therapy (targets liver)

Sepoterin: more cofactor might drive enzyme to work faster. This is something can be tried for every patient. If patient responds it can allow them to increase tehir protein intake to improve QOL.
Pegvaliase: for adults only. degrades Phe in the blood. Some can eat a regular diet. Commitment to eating more protein though -> if not enough Phe in the body can lead to catabolism.

Question 4

Patient with:
- urine that turns dark when exposed to air
- skin discoloration
- elevated homogentistic acid in urine sample
What medical advice would be most applicable for this patient?

Answer 4

• avoid or reduce high-impact exercises in order to prevent joint trauma

Alkaptonuria (homogentisate oxidase deficiency) leads to development of arthritis and tendon dysfunction
later in life

Question 5

In pateints with alkaptonuria, the pathological cahnges are direct results of the ….

Answer 5

accumulation of a poorly soluble metabolite

metabolite = homogentisate (homogentisic acid)

Question 6

Glucose-6-phosphate is an important hub in the cellular biochemical network for carbohydrate metabolism, because it can be converted to many compounds by a single enzymatic reaction. Which one of the following compounds, however, is not within a single enzymatic reaction step from glucose-6-phosphate?
A. fructose-6-phosphate
B. glucose
C. glucose-1-pohsophate
D. 6-phosphogluconolactone
E. UDP-glucose

Answer 6

E. UDP-glucose

Question 7

In the human metabolic network, which one of the following compounds has the lowest connectivity?
A. alanine
B. glucose
C. glutamate
D. lactate
E. pyruvate

Answer 7

D. lactate

Question 8

A network of biochemical reactions each catalyzed by enzymes which are encoded by an interconnected set of genes taht are regulated in a coordianted fashiona nd response to a set of extracellular signals can be considered to be an example of a
A. democratic network
B. hierarchical network
C. homogeneous network
D. random network
E. scale-free network

Answer 8

B. hierarchical network

Question 9

Random mutagenesis of a mammalian genome generally reveal the following observation: cellular physiology can be robustely sustained initially after a large number of mutation events, but the mutation of one additional gene would lead to the collapse of cell physiology. Knowing the properties of biological netowrks, which one of the following statement is most likely to be true?
A. cell physiology maintenance requires a network in which few nodes have very high connectivity and many more nodes with low connectivity (i.e. hub like configuration)
B. cell physiology maintenance rquires a network with random connectivity
C. cell physiology maintenance requires a very precise number of normal gene (i.e. it demonstrates a threshold effect)
D. cell physiolgy maintaenance requires all of hte genes within the genome
E. cell physiology maintenance requires an unpredictable number of genes

Answer 9

A. cell physiology maintenance requires a network in which few nodes have very high connectivity and many more nodes with low connectivity (i.e. hub like configuration)