lecture 7 ( Intracellular Compartments and Protein Transport)

Question 1

Where did the mitochondria and the choloroplast evolve from?

Answer 1

when an aerobic prokaryote was engulfed by a larger pre-eukaryotic cell.

Question 2

what is the main function of the cytosol?

Answer 2

contains metabolic pathways. Protein synthesis. cytoskeleton (protein filements)

Question 3

what is the main function of the Nucleus?

Answer 3

contains genome (DNA and RNA synthesis)

Question 4

what is the main function of the Endoplasmatic Reticulum?

Answer 4

synthesis lipids and protein

Question 5

what is the main function of the golgi apparatus?

Answer 5

modifications, sorting, and packing of proteins and lipids for secretion (production) or delievery to another orgenelle

Question 6

what is the main function of the lysosomes?

Answer 6

intercellular degradation

Question 7

what is the main function of the Endosomes?

Answer 7

sorting of endocytosed material

Question 8

what is the main function of the mitochondria?

Answer 8

ATP synthesis by oxidative phosphorylation

Question 9

what is the main function of the chloroplasts?

Answer 9

ATP synthesis by photosynthesis

Question 10

what is the main function of the peroxisomes?

Answer 10

oxidation of toxic molecules

Question 11

where protein synthesis occurs mostly?

Answer 11

on the ribosome

Question 12

How proteins are transported to organelles?

Answer 12

by signals that direact the protein to the desired organelle

Question 13

what happens to the proteins that lack signals?

Answer 13

they remain in the cytosol

Question 14

what is the function of the nuclear pore?

Answer 14

selective gates that actively transport specfic molecules

Question 15

transportation machanism when protein moves from the cytosol into the nucleus:

Answer 15

transported through nuclear pores

Question 16

Transportation mechanism of protein moving from cytosol into ER, mitochondria, peroxisom, and chloroplast:

Answer 16

transported across the organelle membrane by protein translocators located in the membrane. The protein must unfold to snake through the translocator.

Question 17

transportation mechanism of the proteins moving from the ER to other compartments:

Answer 17

transported to different destination by vesicles

Question 18

what is the function of the signal sequence?

Answer 18

it direct the proteins to correct destination

Question 19

what is typical sorting signal?

Answer 19

is a continuous stretch of amino acids (15-60) amino acid long. the signal sequnce is often removed once the proteins go to their destination.

Question 20

can signals be removed or added to cytosolic protein?

Answer 20

yes, the adding and deleting signal will cause different transportation of different protein

Question 21

what does the inner membrane contain?

Answer 21

it contains some proteints that provide space (anchorge) for the nuclear lamina

Question 22

what is the lamina?

Answer 22

a network of protein filaments that line the inner face of the membrane (inner)

Question 23

How many proteins contained in the nuclear pores?

Answer 23

30 different proteins

Question 24

True or False: large, non-soluble molecules can pass freely into the nulceus.

Answer 24

False, only small water-soluble molecules can pass freely and non selectively into the nucleus and that is because of the proteins that line the nuclear pores. They form a soft segments that fills the center of the pore.

Question 25

How does Large molecules such as proteins pass through the nuclear pores?

Answer 25

these large protein display nuclear localisation signal which is a short sequence of positively charged lysine or arginine…

Question 26

how does the nuclear pores transports to the inside of the nucleus?

Answer 26

1) cytosolic protein import receptor to interact with the nuclear localisation sequence.
2) then the nuclear import receptors moves with the short amino acids in the central region and into the nucleaus
3) Ran-GTP binds to the receptor and deattch the protein which is delivered to the nucleus
4) Ran-GTP dissociate from the receptor in the cytosol by hydrolysing itself into Ran-GDP, this froms phosphorus iodide.

Question 27

What is the receptor function?

Answer 27

it helps direct a newly synthesised protein to the pores by interacting with the cytosolic fibers in the cytosol.

Question 28

True or False: The nuclear import receptor deliever the protein and return to the cytosol

Answer 28

TRUE