Lysosomes

Question 1

Describe the structure of lysosomes?

Answer 1

Single membrane
~100 lysosomes per cell
pH (4-5) => acidic
~40 hydrolytic enzymes=> protease, lipase, nucleas, glycosidase
Heterogenous contents=> different lysosomes look different due to different contents

Question 2

Substrate delivery to lysosome
Extracellular substrates
Intracellular substrates

Answer 2

Extracellular (outside cell) substrates
- fluid phase endocytosis of molecule + lipoproteins

Intracellular( inside cell) substrates
-microautophagy=> invagination of lysosomal membrane
-macroautophagy=> cytosol or organelles wrapped in ER
Membrane which fuses with lysosomes
Selective transport of proteins across lysosomal membrane

Question 3

What is LDL?

Answer 3

Low density lipoproteins

Is most important source of cholesterol to cells in body

Question 4

What are 3 steps of phagocytosis?

Answer 4

Engulfment
Lysosome fusion
Digestion

Question 5

What binds to mannose 6 receptor?

Answer 5

Mannose 6 phosphate

Question 6

I cell disease is caused by mutation of….

Answer 6

Mutation of phosphorylated lysosomal enzyme

Question 7

What is autophagy?

Answer 7

Lysosomes use their hydrolytic enzymes to recycle cell’s own organic material

Question 8

What happens in autophagy?

Answer 8

Lysosome fuses with vesicles containing damaged organelles

Hydrolytic enzymes digest organelle components