Biodegradation and Biosynthesis

Question 1

what are lysosomes?

Answer 1

biological ‘bins’ of the cell. Recycles and degrades molecules and contains >60 hydrolytic enzymes. The internal environment is acidic

Question 2

what are glycoproteins?

Answer 2

involved in adhesion and recognition

Question 3

what are glycolipids and give an example

Answer 3

involved in the cell membrane. Eg gangliosides which contain ceramide which is the lipid backbone and oligosaccharides which attach to the ceramide

Oligosaccharides are progressively degraded in lysosomes

Question 4

Describe Gaucher’s disease

Answer 4

defect in beta-glucosidase enzyme which removes the last glucose off the ceramide backbone and therefore leads to buildup of glucose-ceramide molecules which are toxic

Question 5

Describe Guacher’s type 1

Answer 5

Type 1 = non-neuropathic
- some enzyme activity which means neural cells are not affected as neural cells are turned over slowly and therefore less enzyme is required as less gangliosides are being degraded

• blood cells are affected as they are turned over faster and there is not enough beta-glucosidase to break down the blood cells == hepatosplenomegaly

Question 6

Describe type 2 and 3

Answer 6

both neural

Type 2 = die at 3 as there are 0% enzyme activity = seizures
caused by a lysine 444 proline (444th amino acid becomes proline) - missense

Type 3 = slower onset than type 2
- lysine 444 proline mutation but there are protective polymorphisms

Question 7

Treatment of gauchers disease?

Answer 7

enzyme replacement therapy

- only treats type 1 as drugs cant cross the blood-brain barrier in type 2 and 3 as theyre neural

Question 8

Describe Tay-Sachs disease

Answer 8

autosomal recessive
defective beta-hexosaminidase

Accumulation of intermediate gangliosides

Infantile - deaf, blind - death by 5 years old
Juvenile - rare (5-15 years)
Late-onset - 30s and neurodegenerative

Question 9

Describe mucopolysaccharidosis?

Answer 9

defects in GAG breakdown - skeletal and neural

Question 10

Example of mucopolysaccharidosis?

Answer 10

Hunters disease

Question 11

Describe hunters disease

Answer 11

X linked recessive
Iduronate sulphatase defect
no GAG breakdown = buildup of GAGs

leads to muscle weakness and respiratory problems

Question 12

What is a possible treatment method for disease affecting biodegradation pathways

Answer 12

Gene therapy which involves genetic editing so that patients can produce enzymes which they are deficient/defective for

Question 13

Where does haem synthesis take place?

Answer 13

85% in red blood cells (haemoglobin)

15% in liver .(cytochrome p450)

Question 14

What contains haem?

Answer 14

haemoglobin, cytochrome p450, myoglobin, catalase and peroxidase