Cell Organelles

Question 1

What kind of cells contain relatively more Rough ER?

Answer 1

Pancreatic exocrine cells

Question 2

What is the luminal compartment of the ER called?

Answer 2

Cisternal compartment

Question 3

Which organelle is larger in cells that make secreted protein?

Answer 3

Rough ER

Question 4

Which part of a growing polypeptide directs it to the endoplasmic reticulum?

Answer 4

The signal sequence

Question 5

What are the two main structural differences between the RER and SER?

Answer 5

RER: Elongated cisternae, studded with ribosomes
SER: Tubular cisternae, lacks ribosomes

Question 6

What is the difference in function between the RER and SER?

Answer 6

RER: Protein synthesis for intracellular use or exportation
SER: Lipid synthesis, glycogen metabolism, detoxification, calcium regulation

Question 7

What are the functions of the Golgi apparatus?

Answer 7

Modification of carbohydrates attached to glycoproteins and proteoglycans, poly/oligo-saccharide synthesis, synthesis of sphingomyelin and glycosphingolipids, packing/sorting secretory products

Question 8

What happens to the Golgi apparatus during mitosis/meiosis?

Answer 8

It disassembles then reassembles in interphase

Question 9

What is the purpose of a mannose-6 phosphate (M6P) tag?

Answer 9

It marks precursor proteins (acid hydrolases) that are destined for transport to lysosomes. Occurs in the Golgi.

Question 10

Where do Clathrin-coated vesicles transport products to and from?

Answer 10

From the Golgi apparatus to lysosomes AND from the exterior of the cell to lysosomes

Question 11

Where do COP-coated vesicles transport products to and from?

Answer 11

From one stack of the Golgi apparatus to another (COP1) AND from the endoplasmic reticulum to the Golgi apparatus (COP2)

Question 12

What is the role of dynamin?

Answer 12

It surrounds the neck of the a budding vesicle and pinches it off.

Question 13

What is the role of adaptins?

Answer 13

The mediate clathrin binding to a vesicle

Question 14

Describe the main steps of the lysosomal sorting pathway.

Answer 14

1. M6P is used to tag lysosomal enzymes
2. Lysosomal enzymes bind to M6P receptor and the vesicle buds off
3. M6P receptor is returned to the Golgi for recycling

Question 15

How do lysosomes maintain an acidic environment?

Answer 15

Through ATP-dependent H+ pumps

Question 16

What is the difference between a primary lysosome and a secondary lysosome?

Answer 16

Primary lysosomes are the storage sites for lysosome hydrolases. Secondary lysosomes form when a primary lysosome fuses with an endosome.

Question 17

What is familial hypercholesterolemia?

Answer 17

Mechanism of cholesterol uptake is disrupted. Characterized by elevation of LDL usually due to defect in LDL receptors. High levels of LDL can lead to atherosclerotic plaques.

Question 18

What are the functions of peroxisomes (microbodies)

Answer 18

Synthesis and degradation of hydrogen peroxide, Beta-oxidation of LCFAs, bile acid/cholesterol synthesis, and detoxification of alcohol.

Question 19

Describe Zellweger Spectrum disorders.

Answer 19

Peroxisome biogenesis disorders. 12 genes are required for peroxisome synthesis. A defect in any of them can result in a disorder on the spectrum. The most serious is Zellweger Syndrome, which usually causes death within the first year.

Question 20

Mutations in what part of mitochondrial DNA has been linked to over 200 disease states?

Answer 20

DNA encoding for mitochondrial tRNAs