Lecture 10: Lysosome Flashcards
Where can you find Lysosomes?
Found inside eukaryotic cells
What is the role of a lysosome?
To break down and recycle cellular waste and foreign invaders.
What’s the name of the enzymes within the lysosomes called?
Hydrolytic enzymes
What are the enzymes within lysosomes capable of breaking down?
Macromolecules such as:
Lipids
Proteins
Carbohydrates
What is the name of the processes possible due to the high concentration of hydrolytic enzymes?
Autolysis
Endocytosis
What is Endocytosis?
The process by which cells take in large molecules and other particles from the outside environment
Describe the steps of Endocytosis
The lysosome fuses with the endosome.
This creates a vesicle formed from the plasma membrane.
The resulting hybrid organelle digests the foreign substance.
Who was responsible for discovering the lysosome?
Christian de Duve
Name the 3 features within the membrane of the lysosome
Lipid Layer
Hydrolytic enzyme mixture
Glycosylated membrane transport proteins
What is the role of the single lipid bilayer?
Acts as a barrier to prevent the contents of the lysosome from spilling into the cytoplasm
Name some examples of Hydrolytic enzymes that the lysosome contains (3)
Acid phosphatases
Beta-galactosidases
Cathepsins
Name the membrane proteins found on lysosomes? (4)
Lamp-1
Lamp-2
v-SNAREs
t-SNAREs
What is the role of the membrane proteins found on lysosomes?
Regulates the acidity within the lysosome
Helps maintain it’s structural integrity
What protects the inside of the lysosome? (the part that contains all the enzymes)
A thin layer of carbohydrate molecules (glycocalyx)
What is the role of glycocalyx?
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
What are the 4 key functions of the lipid bilayer of the lysosome?
Maintaining membrane stability
Regulating transport
Maintaining acidity
Protecting against lytic enzymes
Why is it important to maintain the acidity of the lysosome?
The hydrolytic enzymes within the lysosome require a low pH environment in order to function effectively
What is the glycocalyx comprised of?
Glycoproteins and Glycolipids
What are the membrane proteins, v-SNAREs and t-SNAREs involved in?
Regulates the transport of substances into and out of the lysosome
What is the role of Lamp-1 and Lamp-2?
Maintains the stability of the lysosomal membrane.
Prevents the contents from spilling into the cytoplasm
What is found in the cell membrane that helps maintain the low pH environment, and how does it do it’s job?
Proton pump H+- ATPase
It pumps protons into the lysosomal lumen
What is the pH found in the lysosome?
4
What is the name of the bond that the lysosomal enzymes target?
Peptide bond
What happens if the enzymes escape from the lysosome?
Death lmao
Specifically cell death
What structure helps anchor Von Willebrand factor to the endothelium?
Glycocalyx
Why are hydrogen pumps constantly pumping H+ into the lysosome? (not about maintaining acidity)
Protons are extremely small and will naturally leak out of the membrane.
The protein pump needs to shuttle them back in where they belong
Lysosomes can cause what condition to trigger in cancer patients?
Cachexia
Slide 10
