Lecture 10: Lysosome

Question 1

Where can you find Lysosomes?

Answer 1

Found inside eukaryotic cells

Question 2

What is the role of a lysosome?

Answer 2

To break down and recycle cellular waste and foreign invaders.

Question 3

What’s the name of the enzymes within the lysosomes called?

Answer 3

Hydrolytic enzymes

Question 4

What are the enzymes within lysosomes capable of breaking down?

Answer 4

Macromolecules such as:
Lipids
Proteins
Carbohydrates

Question 5

What is the name of the processes possible due to the high concentration of hydrolytic enzymes?

Answer 5

Autolysis
Endocytosis

Question 6

What is Endocytosis?

Answer 6

The process by which cells take in large molecules and other particles from the outside environment

Question 7

Describe the steps of Endocytosis

Answer 7

The lysosome fuses with the endosome.
This creates a vesicle formed from the plasma membrane.
The resulting hybrid organelle digests the foreign substance.

Question 8

Who was responsible for discovering the lysosome?

Answer 8

Christian de Duve

Question 9

Name the 3 features within the membrane of the lysosome

Answer 9

Lipid Layer
Hydrolytic enzyme mixture
Glycosylated membrane transport proteins

Question 10

What is the role of the single lipid bilayer?

Answer 10

Acts as a barrier to prevent the contents of the lysosome from spilling into the cytoplasm

Question 11

Name some examples of Hydrolytic enzymes that the lysosome contains (3)

Answer 11

Acid phosphatases
Beta-galactosidases
Cathepsins

Question 12

Name the membrane proteins found on lysosomes? (4)

Answer 12

Lamp-1
Lamp-2
v-SNAREs
t-SNAREs

Question 13

What is the role of the membrane proteins found on lysosomes?

Answer 13

Regulates the acidity within the lysosome
Helps maintain it’s structural integrity

Question 14

What protects the inside of the lysosome? (the part that contains all the enzymes)

Answer 14

A thin layer of carbohydrate molecules (glycocalyx)

Question 15

What is the role of glycocalyx?

Answer 15

Protects the lysosome from attack by lytic enzymes. Lytic enzymes are able to break down the lysosome so it’s important that there’s a physical barrier that blocks access to the underlying membrane

Also plays a role in regulating the transport of substances into and out of the lysosome

Question 16

What are the 4 key functions of the lipid bilayer of the lysosome?

Answer 16

Maintaining membrane stability
Regulating transport
Maintaining acidity
Protecting against lytic enzymes

Question 17

Why is it important to maintain the acidity of the lysosome?

Answer 17

The hydrolytic enzymes within the lysosome require a low pH environment in order to function effectively

Question 18

What is the glycocalyx comprised of?

Answer 18

Glycoproteins and Glycolipids

Question 19

What are the membrane proteins, v-SNAREs and t-SNAREs involved in?

Answer 19

Regulates the transport of substances into and out of the lysosome

Question 20

What is the role of Lamp-1 and Lamp-2?

Answer 20

Maintains the stability of the lysosomal membrane.
Prevents the contents from spilling into the cytoplasm

Question 21

What is found in the cell membrane that helps maintain the low pH environment, and how does it do it’s job?

Answer 21

Proton pump H+- ATPase

It pumps protons into the lysosomal lumen

Question 22

What is the pH found in the lysosome?

Answer 22

4

Question 23

What is the name of the bond that the lysosomal enzymes target?

Answer 23

Peptide bond

Question 24

What happens if the enzymes escape from the lysosome?

Answer 24

Death lmao
Specifically cell death

Question 25

What structure helps anchor Von Willebrand factor to the endothelium?

Answer 25

Glycocalyx

Question 26

Why are hydrogen pumps constantly pumping H+ into the lysosome? (not about maintaining acidity)

Answer 26

Protons are extremely small and will naturally leak out of the membrane.
The protein pump needs to shuttle them back in where they belong

Question 27

Lysosomes can cause what condition to trigger in cancer patients?

Answer 27

Cachexia

Question 28

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