Endomembrane system

Question 1

What is the function of the endomembrane system?

Answer 1

A group of membranous organelles with the task of modifying, packaging and transporting lipids and proteins and cellular digestion

Question 2

What is the pathway for proteins?

Answer 2

Nucleus -> ER -> Golgi -> Cell membrane

Question 3

What are the organelles part of the endomembrane system?

Answer 3

ER
Golgi apparatus
vesicles
Lysosomes
Vacuoles
Plasma membrane

Question 4

What is the function of the RER

Answer 4

Protein synthesis: mRNA attaches to ribosome on RER and is translated in the lumen of ER. Folds and modifies newly built proteins.

Question 5

What is the function of Lysosomes?

Answer 5

: acidic vesicles of digestive enzymes that breakdown & recycle food,debris, bacteria, etc

Question 6

What is the Function of SER

Answer 6

Lipid synthesis and detoxifies drugs/posions

Question 7

What is the function of the

Question 8

Endomembrane system

Answer 8

A group of membrane-bound organelles inside a eukaryotic cell.
Includes many organelles that are interconnected by vesicles (little
membrane bubbles

Question 9

Protein secretion

Answer 9

A process by which a substance is released into the environment

Question 10

Nucleus

Answer 10

a rounded structure that contains & protects most of a eukaryotic cell’s DNA

Question 11

Nuclear envelope

Answer 11

the double-membrane that surrounds the nucleus & acts as its barrier

Question 12

Nuclear Pores

Answer 12

tiny “holes” in the nuclear envelope that allow entry/exit into & out of the
nucleus.

Question 13

Nucleolus

Answer 13

a small dense structure inside the nucleus where ribosomes are assembled

Question 14

ER

Answer 14

Endoplasmic Reticulum: membranous structures continuous with the nuclear
envelope.
- ER Lumen: the internal space/compartment of the ER.
1) Rough ER: closer to the nucleus with a rough, ribosome-coated surface.
- Newly built proteins fold & are modified in the rER lumen.
2) Smooth ER : further from nucleus with a smooth, ribosome-free surface.
- Synthesizes lipids & detoxifies drugs/poisons

Question 15

Golgi Apparatus

Answer 15

Molecules synthesized in the ER (e.g. proteins & lipids) are transported by vesicles to the Golgi apparatus

Question 16

Golgi Apparatus structure

Answer 16

stack of flat, membranous sacs (cisternae) that function as a“processing center.”

Question 17

Golgi Apparatus function

Answer 17

Receives vesicles, modifies vesicle contents, & repackages contents into vesicles for export.
* Receiving end of the Golgi = “Cis” end. - Shipping end of the Golgi = “Trans” end.
* Some vesicles shipped from Golgi apparatus can fuse with the cell membrane for secretion.

Question 18

Cell/Plasma membrane

Answer 18

It is a selective
* Made of a double layer of
phospholipids , with hydrophilic
and hydrophobic regions.
* Also has embedded proteins and
carbohydrate chains on the
outside.

Question 19

Cellular Digestion

Answer 19

Some of the organelles of the endomembrane system are more specialized
for cellular digestion. E.g. Digestion Lysosomes, Peroxisomes and Vacuoles

Question 20

Lysosomes

Answer 20

acidic vesicles of digestive enzymes that breakdown & recycle food,
debris, bacteria, etc.
- Primarily it is found only in animal cells & originate at the Golgi apparatus

Question 21

Peroxisomes

Answer 21

vesicles of enzymes that breakdown TOXIC compounds (converting it
to H2O2) & fatty acids.
- It is found in all eukaryotic cells
& originate at the rER .

Question 22

Vacuoles

Answer 22

• Vacuoles are large vesicles derived from the ER and Golgi apparatus.
• Vacuoles perform a variety of functions in different kinds of cells:
• 1) Transport (vesicles); (2) Storage (food vacuoles);
  (3) Water balance (central vacuole & contractile vacuole)

Question 23

Types of Vacuoles

Answer 23

• Food Vacuoles are formed by phagocytosis.
  *Central vacuoles, found in many mature plant cells, contain a solution called
  sap.
• It is the plant cell’s main repository of inorganic ions, including
  potassium and chloride.
• The central vacuole plays a major role in the growth of plant cells
• Contractile, found in many freshwater protists, pumps excess
  water out of cells.

Question 24

Mitochondrion

Answer 24

Found in nearly all eukaryotic cells
* Have their own DNA
* Reproduce by binary fission
* Double membrane: a smooth outer
membrane and an inner membrane folded
into cristae
* The inner membrane creates two
compartments: intermembrane space
and mitochondrial matrix.

Question 25

Chloroplast

Answer 25

Chloroplasts, found in plants and
algae
* Contains green pigment
chlorophyll, as well as enzymes
and other molecules
* Chloroplast structure includes
-Thylakoids, membranous sacs,
stacked to form a granum
-Stroma, the internal fluid
* Convert light energy into chemical
energy.
* Own DNA
* Reproduce via Binary Fission