Protein Trafficking

Question 1

Pathways cells use to moves proteins across plasma membrane

Answer 1

Carrier proteins, channels, endocytosis (caveolae-mediated, receptors, receptor-mediated), exocytosis, phagocytosis, transcytosis

Question 2

Carrier proteins

Answer 2

Bring proteins across the membrane that cannot simply diffuse

Question 3

Channel proteins

Answer 3

Allows the protein to enter when given the signal to

Question 4

Caveolae-mediated endocytosis

Answer 4

Pit lined with caveolin brings molecules in a membrane bound vesicle

Question 5

Receptor-mediated endocytosis

Answer 5

Bound receptors in coated pits get encircled by coated vesicle

Question 6

Exocytosis

Answer 6

Early endosome is at a low pH, late endosome fuses with a lysosome to break down material and then fuses with a phagosome to dispose of the material

Question 7

Phagocytosis

Answer 7

Microbe is encapsulated and combines with lysosome to create phagolysosome, and digested material is released

Question 8

Transcytosis

Answer 8

Molecules are brought into the cell via vesicle, then released

Question 9

Bilayer sheet

Answer 9

Make up membranes, composed to two sheets, the lipid bilayer

Question 10

Liposome

Answer 10

Spherical lipid bilayers, inside is hollow or filled with liquid

Question 11

Micelle

Answer 11

Spherical, single lipid layer, outside is polar while inside is nonpolar

Question 12

Channels

Answer 12

Use passive diffusion and go with the concentration gradient

Question 13

Pumps

Answer 13

Use active energy-dependent transport and goes agains the concentration gradient

Question 14

ABC transporters

Answer 14

Ligand binds open dimer, ATP binding causes a conformational change that releases the ligand, ATP hydrolyzed and ADP released to open up the dimer again

Question 15

Nucleus

Answer 15

Made up of two lipid bilayers (inner and outer membranes) separated by perinuclear space (lumen). Membranes have nuclear pores

Question 16

How do proteins enter the nucleus?

Answer 16

Small proteins can just diffuse in, but larger proteins need a nuclear localization signal bound to get through the nuclear pore

Question 17

ER/Golgi membrane protein trafficking pathway

Answer 17

Proteins co-translationally inserted into RER through translocons, packaged into vesicles in RER, vesicles take proteins to Golgi, where the proteins are sorted and sent to either the lysosome, plasma membrane, or secretory vesicle

Question 18

Misfolded/unfolded proteins

Answer 18

Chaperone takes protein to an ER protein translocator and takes into cytoplasm where ubiquitin tags it and sends to the proteosome, which degrades it into small peptides and amino acids to be recycled

Question 19

Lysosome function

Answer 19

To degrade macromolecules and cells using internal low pH and acid hydrolases

Question 20

Lysosome storage diseases

Answer 20

Tay-Sachs, Guacher’s, metachromatic leukodystrophy
Caused by mutations in lysosome that prevent breakdown of damaged proteins, so these proteins are stored when they shouldn’t be

Question 21

Cystic fibrosis

Answer 21

Caused by mutation in CFTR gene where there is no Ca2+ channels on the epithelial cells, leading to dehydration of tissues and mucous

Question 22

Botulism

Answer 22

Blocks SNARE interactions so neurotransmitters are released by the presynaptic cell, but cannot be taken up by the post-synaptic cell. Causes autonomic system to fall apart.