Cell biology IV Flashcards Preview

Year 1 Cell Biology > Cell biology IV > Flashcards

Flashcards in Cell biology IV Deck (55):
1

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

Atlastin

2

What class of protein is atlastin?

GTPase

3

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

1) Increased ER membrane fusion2) Absence of Golgi

4

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

ER fragmentation

5

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

Atlastin

6

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

Atlastin

7

What condition arises due to atlastin deficiency?

Hereditary spastic paraplegia

8

What are symptoms of hereditary spastic paraplegia?

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

9

Proteasomes make up what percentage of cellular proteins?

1%

10

Are proteases ATP-dependent?

Yes

11

Where are proteasomes located in the cell?

Cytoplasm and nucleus

12

Proteasomes are involved in proteolysis of what types of proteins?

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

13

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

Can be either (both)

14

Proteasomes are inhibited by what type of molecule?

Abnormal prion proteins

15

What effect to abnormal prion proteins have on proteasomes?

Inhibition

16

Defective proteolysis by proteasomes is causative in what diseases?

Parkinson's disease, cystic fibrosis

17

What is the function of bortezomib in cancer cell therapy?

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

18

In polarized cells, where is the Golgi located?

Between the nucleus and apical cytoplasm

19

When is a negative Golgi image seen?

In active protein-secreting cells

20

What is a negative Golgi image?

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

21

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

Presents toward the transitional ER where transport vesicles are forming

22

What is formed from the trans-Golgi?

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

23

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

Golgi

24

Where is the mutation in Wilson's disease?

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

25

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

Impaired biliary excretion of copper

26

What is the role of dysferlin?

Repair of microperforations in skeletal muscle plasma membranes

27

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

Dysferlin

28

The patching mechanism of dysferlin is dependent upon what mineral?

Calcium

29

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

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

30

How does a mutation in proinsulin lead to proinsulinemia?

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

31

What are the four types of endosomal compartments?

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

32

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

Periphery

33

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

Early endosomes, recycling endosomes

34

What is the pH of early endosomes and recycling endosomes?

6.2 - 6.5

35

Which endosomal compartments have a pH of 6.2 - 6.5?

Early endosomes, recycling endosomes

36

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

Recyling endosome

37

What is the pH inside multivesicular bodies?

5.0 - 6.2

38

Which endosomal compartment has a pH of 5.0 - 6.2?

Multivesicular bodies

39

What do multivesicular bodies eventually fuse with?

Late endosomes

40

Do multivesicular bodies have a secretory role?

Yes

41

Where are late endosomes located in the cell?

Near Golgi and nucleus

42

Late endosomes either fuse or mature into _______

Lysosomes

43

What is another term for late endosomes?

Prelysosomes

44

What is the pH of late endosomes?

5.0

45

Which endosomal compartment has a pH around 5.0?

Late endosome

46

What are the four fates of receptor-ligand complexes?

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)

47

What do lysosomes transport?

Lysosomal hydrolases and other ions and molecules

48

In which cell type are lysosomes most abundant?

Phagocytic cells (macrophages, neutrophils)

49

What is an autophagolysosome (secondary lysosome)?

Primary lysosome + autophagosome

50

Primary lysosome + autophagosome = ?

Autophagolysosome (secondary lysosome)

51

What is a heterophagolysosome?

Primary lysosome + heterophagosome

52

Primary lysosome + heterophagosome = ?

Heterophagolysosome

53

What are residual bodies?

Lysosomes that contain undigested waste

54

Accumulated waste in residual bodies eventually forms what inclusion?

Lipofuscin

55

Are lysosomes acidophilic or basophilic?

Acidophilic