Endomembrane system and bulk transport process

Question 1

What is the endomembrane system?

Answer 1

It is a membrane system where organelles are interconnected by direct physical contact or carried through by vesicles.
Refer to diagram in notes

Question 2

Important components of the endomembrane system?

Answer 2

*Nuclear envelope
*ER (smooth and rough)
* Golgi Apparatus
*vesicles
* Plasma membrane

EXTRAS
* Lysosome
*Vacuole

Question 3

What can the plasma and organelle membranes do?

Answer 3

They can merge as they both are made of the phospholipid bilayer, makes it easier to move things around

Question 4

Protein factory (me as a baby protein going to kindergarten)

Answer 4

How its synthesised, packaged and final destination

*Synthesised in ER
*Packaged in Golgi apparatus
* Transported by vesicles

Question 5

ER

Answer 5

Means inside cell in cytoplasm, forms a meshwork. Flat tubule like structurez.

Has an outer membrane and and inner lumen (cavity).

Two types based on looks:
*Rough - rough surface cause of ribosomes
*Smooth - smooth surface

Question 6

sER

Answer 6

*Metabolises carbs for ATP
*Synthesises lipids for membranes
* Detoxifies drugs and toxins
* Stores Ca ions as these are crucial for signalling and activation of processes
* There is a lot of sER in cells that is very active in these processes and the amount of sER increases/decreases based on need

Question 7

rER

Answer 7

• rough cause of ribo and they make proteins
• Proteins made, enter lumen of rER, then processed and either
• secreted and released in a vesicle to mostly go to the golgi apparatus OR
• retained and kept to become membrane proteins

Question 8

Free floating proteins….

Answer 8

Made by free floating ribosomes in the cytoplasm

Question 9

What does the Golgi apparatus do?

Answer 9

*flat, tubular structures, pancakes, close to ER, tightky packed, pancakes, PANCAKES

• receive, modify, sort and ship proteins that arrive from the cis surface (facing the ER, receiving end) and release from trans area (facing away)

Glycosylation

Question 10

Glycosylation

Answer 10

adds carbs/modifies existing carbs onto proteins

essential for the glycoproteins in the cell membrane for recognition

Also produces polysaccharides that are secreted from cell

Question 11

Sorting proteins

Answer 11

Adds a little tag, could be a little sugar, so they go to the right vesicle

Question 12

Direct vesicle traffic

Answer 12

Tags vesicles with little proteins so it knows where to go i.e either to be secreted through plasma membrane pathways or to become one with the membrane or to go to a lysosome.

Question 13

Types of vesicles

Answer 13

Has a phospholipid bilayer membrane, has a coat protein to form vesicle properly, has a fluid/cytoplasmic inside, has some stuff

*Transport - from one place to another
*Secretory - take stuff to plasma mem, go through and secrete stuff outside cell
*Vacuoles - BIIIIG vesicle

Question 14

Artificial vesicle

Answer 14

Eg Liposomes, has a lipid bilayer, can be used as a vessel in drugs and vaccines

Question 15

Bulk transport types

Answer 15

Exocytosis
Endocytosis

Question 16

Exocytosis

Answer 16

Takes things out of cell or to cell surface

*Constitutive - to contribute to a constitution, takes ECM fibres out of cells
* Regulated - is controlled and releases in response to a signal i.e like neurotransmitters and hormones

Question 17

Endo types

Answer 17

Phago-
Pino -

Question 18

Phagocytosis

Answer 18

Taking in food or other particulate from outside, the membrane engulfs it then breaks off to form a phagocytic vacuole, then takes to lysosome which breaks it down with digestive enzymes

Done in macrophages

Question 19

Pinocytosis

Answer 19

Cell drinking, takes in fluids and solute particles like sugars and proteins, whatever it can take in (non-selective), vesicle forms with the help of coat proteins

Question 20

Receptor mediated endo

Answer 20

*Type of pinocytosis
*Receptors on plasma membrane detect and selectively pick the target solute in the ECM which may be of low conc.
*Receptor curves inwards and coat proteins form a vesicle around it
*May randomly get a useless solute, its okai

Question 21

Lysosome (cheeseburger)

Answer 21

*It has a v specific environment
* It merges with a phagocytic food cell
* It has hydrolytic enzymes that breakdown the food, inside is v acidic as the enzymes produced by ER and Golgi are activated by this pH
*A cheese burger has carbs, lipids, protein and nucleic acids. Enzymes break it down into building blocks to use for something else

Question 22

Autophagy (lysosomal thing)

Answer 22

*self-eating, important for the cell. If we don’t want certain structures, the lysosome fuses with the vesicles, breaks down stuff inside and recycles the mats
*Mats are good because a lot of E and resources were put into making them so why waste
*If lysosomes weren’t packaged or tagged properly, they don’t digest the unwanted cells, buildup of unwanted = bad
*Lysosomal digestion is imp in programmed cell death where cells intentionally die, it kind of initiates that