Chapter 15

Question 1

Pathways, synthesis, cytoskeleton

Answer 1

Cytosol

Question 2

Contains genome. DNA and RNA synthesis

Answer 2

Nucleus

Question 3

Synthesis of lipids and proteins destined for organelles and membrane

Answer 3

Endoplasmic reticulum

Question 4

Sorting and packaging of protein/lipids for transport or secretion

Answer 4

Golgi

Question 5

Intracellular degeneration
Cell garbage/recycling

Answer 5

Lysosomes

Question 6

Sorting of endocytosis material

Answer 6

Endosomes

Question 7

ATP synthesis via oxidative phosphorylation

Answer 7

Mitochondria

Question 8

ATP synthesis via carbon fixation/Photosynthesis

Answer 8

Chloroplasts

Question 9

Oxidative breakdown of toxic molecules

Answer 9

Peroxisomes

Question 10

Three mechanisms for protein, transportation into organelle

Answer 10

Nuclear pore
Across membrane
Vesicles

Question 11

Direct proteins to correct organelle/compartment

Answer 11

Signal sequences

Question 12

Signal sequence unique to proteins destined for ER

Answer 12

N-terminal

Question 13

Proteins enter nucleus through…

Answer 13

Nuclear pore with tentacles that allow water-soluble, small molecules pass.

Question 14

Protein enter nucleus steps

Answer 14

Nuclear import receptor direct protein to pore
cause poor to open
release protein

Question 15

GTP hydrolysis

Answer 15

Drives Nuclear transport
1) Nuclear import receptor brings protein from cytosol to nucleus
2) Receptor binds to RAN-GTP releasing protein
3) Empty receptor and RAN-GTP transported back to cytosol
4) RAN hydrolysis the bound GTP
5) RAN-GDP detach from receptor for new protein

Question 16

Types of RAN

Answer 16

1) GTP: concentrated in nucleus
2) GDP: concentrated in cytosol
3) GAP: converts GTP to GDP
4) GEF: causes loss of GDP and uptake of GTP

Question 17

Protein enter mitochondria…

Answer 17

Unfolded

Question 18

Steps for protein to enter mitochondria

Answer 18

1) Import receptor recognizes N-terminal signal sequence
2) protein, import receptor, translocator, laterally diffuse across membrane till recognized by translocator from inner membrane
3) protein, snakes into matrix where signal peptide is cleaved off
4) chaperone protein plus ATP fold protein

Question 19

Proteins enter peroxisomes

Answer 19

From cytosol and ER

Question 20

Proteins enter ER…

Answer 20

Soluble proteins made by ribosomes on ER, then released into ER lumen

Question 21

Synthesize proteins that will stay in cell to function

Answer 21

Free ribosomes

Question 22

Synthesize proteins with ER signal sequences and released by cell

Answer 22

Membrane bound ribosomes

Question 23

Two types of proteins transferred to ER

Answer 23

1) Water soluble: completely translocated across ER membrane
2) transmembrane: partially translocated remain embedded in membrane

Question 24

What direct ribosomes to ER membrane

Answer 24

ER signal sequence
Signal recognition particle

Question 25

Steps for ribosome to ER

Answer 25

1) SRP binds to exposed ER signal and ribosome, slowing protein synthesis 2) SRP/ribosome bind to SRP receptor in ER membrane 3) SRP is released, ribosome passed from SRP receptor to protein translocator 4) protein synthesis resumes. Locator moves protein across ER membrane 5) ER signal is bound to trans locator, signal peptide cleaved off and ejected into bilayer 6) once synthesis is complete, translocated protein is released into ER lumen. 7) translocator closes

Question 26

ER Single pass transmembrane protein

Answer 26

Retained in lipid bilayer via stop, transfer sequence. Transfer across ER membrane initiated by ER signal sequence

Question 27

ER multi pass transmembrane protein

Answer 27

Have internal ER sequence. Protein spans membrane multiple times with alternating start stop transfer sequences. SRP recognizes start transfer sequence

Question 28

Junctions between ER and organelles can transfer what?

Answer 28

Lipids