Cell biology IV

Question 1

What protein is involved in constructing and shaping of the sER?

Answer 1

Atlastin

Question 2

What class of protein is atlastin?

Answer 2

GTPase

Question 3

What happens to the ER and Golgi in response to an abundance of atlastin?

Answer 3

1) Increased ER membrane fusion2) Absence of Golgi

Question 4

What happens to the ER as a result of atlastin deficiency?

Answer 4

ER fragmentation

Question 5

ER fragmentation occurs in response to a deficiency in what protein?

Answer 5

Atlastin

Question 6

Hereditary spastic paraplegia is caused from a deficiency in what protein?

Answer 6

Atlastin

Question 7

What condition arises due to atlastin deficiency?

Answer 7

Hereditary spastic paraplegia

Question 8

What are symptoms of hereditary spastic paraplegia?

Answer 8

1) Leg stiffness2) Gait disturbances (stumbling, tripping)

Question 9

Proteasomes make up what percentage of cellular proteins?

Answer 9

1%

Question 10

Are proteases ATP-dependent?

Answer 10

Yes

Question 11

Where are proteasomes located in the cell?

Answer 11

Cytoplasm and nucleus

Question 12

Proteasomes are involved in proteolysis of what types of proteins?

Answer 12

1) Regulating proteins (e.g. cell cycle, txn, apoptosis)2) Malformed, denatured, damaged proteins3) Antigenic proteins (cleaved and presented to T cells)

Question 13

Are proteasomes ubiquitin-dependent, -independent, or both?

Answer 13

Can be either (both)

Question 14

Proteasomes are inhibited by what type of molecule?

Answer 14

Abnormal prion proteins

Question 15

What effect to abnormal prion proteins have on proteasomes?

Answer 15

Inhibition

Question 16

Defective proteolysis by proteasomes is causative in what diseases?

Answer 16

Parkinson’s disease, cystic fibrosis

Question 17

What is the function of bortezomib in cancer cell therapy?

Answer 17

Bortezomib partially inhibits proteasomes, thus decreasing the degradation of pro-apoptotic factors

Question 18

In polarized cells, where is the Golgi located?

Answer 18

Between the nucleus and apical cytoplasm

Question 19

When is a negative Golgi image seen?

Answer 19

In active protein-secreting cells

Question 20

What is a negative Golgi image?

Answer 20

A pale-staining area of cytoplasm seen in H&E staining (neither acidophilic nor basophilic)

Question 21

In which direction is the cis-Golgi oriented in the cell?

Answer 21

Presents toward the transitional ER where transport vesicles are forming

Question 22

What is formed from the trans-Golgi?

Answer 22

1) Secretory granules (vesicles)2) Lysosomes3) Membrane protein-transporting vesicles

Question 23

Where are lysosomal enzymes tagged with mannose-6-phosphate?

Answer 23

Golgi

Question 24

Where is the mutation in Wilson’s disease?

Answer 24

Mutation in a protein pump for copper in the trans-Golgi network of liver cells

Question 25

What is the result of the mutated protein transporter in Wilson's disease?

Answer 25

Impaired biliary excretion of copper

Question 26

What is the role of dysferlin?

Answer 26

Repair of microperforations in skeletal muscle plasma membranes

Question 27

Repair of microperforations in skeletal muscle plasma membranes is accomplished by what molecule?

Answer 27

Dysferlin

Question 28

The patching mechanism of dysferlin is dependent upon what mineral?

Answer 28

Calcium

Question 29

Mutations of the dysferlin gene lead to what three types of muscular dystrophy?

Answer 29

1) Miyoshi myopathy2) Limb-girdle muscular dystrophy type 2b3) Distal myopathy tibialis anterior muscle onset

Question 30

How does a mutation in proinsulin lead to proinsulinemia?

Answer 30

1) Mutated proinsulin is missorted into the unregulated (constitutive) secretory pathway2) Prohormone converting enzymes are properly sorted in the regulated pathway3) Consequently, there is an absence of prohormone converting enzyme activity in the unregulated pathway

Question 31

What are the four types of endosomal compartments?

Answer 31

1) Early endosomes2) Recycling endosomes3) Multivesicular bodies4) Late endosomes

Question 32

Where are early endosomes and recycling endosomes located in the cell?

Answer 32

Periphery

Question 33

Which endosomal compartments are located at the periphery of the cell?

Answer 33

Early endosomes, recycling endosomes

Question 34

What is the pH of early endosomes and recycling endosomes?

Answer 34

6.2 - 6.5

Question 35

Which endosomal compartments have a pH of 6.2 - 6.5?

Answer 35

Early endosomes, recycling endosomes

Question 36

Which endosomal compartment is responsible for glucose transport in response to insulin?

Answer 36

Recyling endosome

Question 37

What is the pH inside multivesicular bodies?

Answer 37

5.0 - 6.2

Question 38

Which endosomal compartment has a pH of 5.0 - 6.2?

Answer 38

Multivesicular bodies

Question 39

What do multivesicular bodies eventually fuse with?

Answer 39

Late endosomes

Question 40

Do multivesicular bodies have a secretory role?

Answer 40

Yes

Question 41

Where are late endosomes located in the cell?

Answer 41

Near Golgi and nucleus

Question 42

Late endosomes either fuse or mature into _______

Answer 42

Lysosomes

Question 43

What is another term for late endosomes?

Answer 43

Prelysosomes

Question 44

What is the pH of late endosomes?

Answer 44

5.0

Question 45

Which endosomal compartment has a pH around 5.0?

Answer 45

Late endosome

Question 46

What are the four fates of receptor-ligand complexes?

Answer 46

1) Receptor is recycled, ligand is degraded or released for use (e.g. LDLr)2) Receptor and ligand are recycled (e.g. TfR)3) Receptor and ligand are degraded (e.g. FGFR3 - reverse occurs, leading to achondroplasia)4) Receptor and ligand are transported across cell and secreted (transcytosis, e.g. antibodies in glandular cells)

Question 47

What do lysosomes transport?

Answer 47

Lysosomal hydrolases and other ions and molecules

Question 48

In which cell type are lysosomes most abundant?

Answer 48

Phagocytic cells (macrophages, neutrophils)

Question 49

What is an autophagolysosome (secondary lysosome)?

Answer 49

Primary lysosome + autophagosome

Question 50

Primary lysosome + autophagosome = ?

Answer 50

Autophagolysosome (secondary lysosome)

Question 51

What is a heterophagolysosome?

Answer 51

Primary lysosome + heterophagosome

Question 52

Primary lysosome + heterophagosome = ?

Answer 52

Heterophagolysosome

Question 53

What are residual bodies?

Answer 53

Lysosomes that contain undigested waste

Question 54

Accumulated waste in residual bodies eventually forms what inclusion?

Answer 54

Lipofuscin

Question 55

Are lysosomes acidophilic or basophilic?

Answer 55

Acidophilic