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Histology > 4. Secretory Pathway and Lysosomes > Flashcards

4. Secretory Pathway and Lysosomes Flashcards

1
Q

All protein translation initiates in the ________.

A

cytosol

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2
Q

If a protein does not have the signal recognition sequence where is the protein translated?

A

Fully translated in the cytosol and that protein remains in the cytosol.

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3
Q

If a protein is fully translated and is in the cytosol and has a specific organelle targeting sequence .. what will happen to the protein?

A

it will be localized to those places (nuclear or mitochondria localiztion)

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4
Q

if a protein has a signal recognition sequence how and where will translation occur?

A

it will be bound by the SRP and complex will dock on the ER membrane where translation continues with the protein going directly into the lumen of ER. (beginning of secretory pathway)

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5
Q

Where is the signal sequence on a protein clipped off?

A

in the lumen of the ER

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6
Q

If a protein is destined to be embedded in a membrane what pathway will it use?

A

Secretory pathway b/c it will have a signal sequence at its N terminus.

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7
Q

Transmembrane proteins (single or multi-pass) are translated by what pathway?

A

secretory pathway

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8
Q

What are the 3 functions of the Golgi Apparatus?

A
  1. Modify proteins
  2. Package proteins
  3. Aid in sorting proteins to the correct location
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9
Q

Specific labeling of lysosomal enzymes starts early in the _________.

A

Cis Golgi network

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10
Q

Where do Glycoproteins combine with specific receptors that guide them to their destination?

A

Trans Golgi Network

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11
Q

What happens after a vesicle buds off from one membrane?

A

It loses its coat protein and recognizes which membrane to transport its cargo by means of protein-protein interactions of SNARE proteins and docking membrane

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12
Q

What are the major COAT proteins of the transport vesicles?

A

COPI, COPII, and clathrin

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13
Q

Type of proteins are involved in transport from the RER to the cis Golgi?

A

COPII

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14
Q

Type of proteins are involved in retrograde transport throughout the Golgi and even back to the RER?

A

COPI

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15
Q

Type of protein involved in transport to the lysosome from either the cell surface or from the trans Golgi?

A

Clathrin

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16
Q

what on a protein defines that the protein is destined for the lumen of the ER?

A

KDEL amino acid sequence

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17
Q

what defines that a protein is destined for the lumen of the lysosome?

A

Mannose-6-phosphate tag

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18
Q

What has both heavy and light subunits that form multimers of 3 each in a triskelion arrangement that helps to stabilize a forming vesicle/pinching off from a membrane?

A

Clathrin

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19
Q

The final pinching off of a vesicle from a membrane is the energy dependent process via a protein called _________?

A

Dynamin

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20
Q

Where does lysosomal targeting begin?

A

RER lumen

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21
Q

In the RER lumen _______ is added to ALL proteins.

A

Mannose

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22
Q

Once proteins are in the cis-Golgi, the mannose is removed from all of the proteins except those that are targeted for _________. What do these proteins have added to them so mannose is not removed?

A
  • lysosome

- Phospate

23
Q

What happens if the lysosomal enzyme accidentally gets secreted?

A

It is brought back into the cell by mannose-6-phosphate receptors on the cell surface and then placed back in the lysosome

24
Q

What are the two types of protection that prevent lysosomal enzymes from attacking and digesting cytoplasmic components.

A
  1. enveloping membrane– that separates the lytic enzymes from the cytoplasm
  2. Lysosomal enzymes are practically inactive at pH 7.2 (cytosolic pH)– if leakage does occur.
25
Q

How do you tell mitochondria from lysosomes?

A

Mitochondria have 2 membranes

-need high res TEM

26
Q

How do you tell lysosomes from peroxisomes?

A

Primary lysosomes should be more electron dense than peroxisomes.
-otherwise you need some sort of immunohistochemistry detection.

27
Q

In regards to immunohistochemistry dection, lysosomes should have ______ and peroxisomes should have ______.

A

acid phosphatase, catalase

28
Q

Lysosomes are ______ in shape and tend to be _____.

A

plemorphic, oval

29
Q

Lysosomes are ____ to ____ in diameter.

A

0.05 to 2.0 um

30
Q

Lysosomes contain a large variety of __________ whose main function is __________.

A

hydrolytic enzymes, intracytoplasmic digestion

31
Q

Lysosomal enzymes have optimal activity at ____.

A

pH 5

32
Q

What is lipofuschin pigment?

A
  • one of the only things that lysosomes cannot breakdown. So gradually accumulates with age
  • In cardiac cells especially.
33
Q

What digest/destroys individual proteins in cytosol?

A

Proteosomes

34
Q

What digest/destroys bulk material proteins, nucleic acids, etc. within the membrane bound compartments?

A

Lysosomes

35
Q

The ubiquitin is added to _______ by special enzymes.

A

lysine residues

36
Q

______ is needed for the protease complex to recognize, unfold and cleave the protein into ________.

A
  • ATP

- 8AA small peptide chains

37
Q

__________ is way of tagging individual proteins for degradation in the cytosol via the proteosome.

A

Ubiquitination

38
Q

What are lysosomes that have not entered into a digestive event?

A

Primary lysosomes

39
Q

Lysosomes can digest materials taken into the cell from its environment, a process called _______.

A

heretophagy

40
Q

Indigestible compounds are retained within the vaculoes which are now called ______.

A

residual bodies

41
Q

Multivesicular body is predominantly when lysosome fuses with a _______ but it can also happen with a ________.

A
  • mitochondria

- peroxisome

42
Q

A more recent classification retains the benchmark of acid hydrolase content, but includes lysosomes as the only one element of the _____________.

A

acid vesicle system

43
Q

The acid vesicle system includes that group of cytoplasmic vesicles that contain within their limiting membranes a membrane __________ which serves as a _________ that can decrease the intravesicular pH to 5

A

H+ATPase

hydrogen pump

44
Q

what is hydrolysis of exogenous substrates?

A

heterolysis

45
Q

What are 3 examples of herterolysis?

A
  1. processing secretory products in glands
  2. reabsorption of protein in proximal tubule of kidney
  3. ingestion and destruction of bacteria by leukocytes and macrophages
46
Q

What is hydrolysis of endogenous substrates?

A

Autolysis

47
Q

What are 2 examples of autolysis?

A
  1. hepatocyte mitochondria in endotoxic shock

2. elimination of excess secretory products e.g. pituitary hormones

48
Q

Why is lysosome function so important to dentist?

A

Very important for orthodontic tooth movement as well as tooth eruption

49
Q

What are the 3 main functions of lysosomes?

A
  1. Heterophagy
  2. Augtophagy
  3. specialized secretion (i.e. for destrucion of a mineralized matrix like bone or teeth)
50
Q

What are suttering-mutations in lysosomal enzymes?

A

GNTAB, GNPTG, and NAGPA

51
Q

What is I-Cell Disease?

A

deficiency in mannose-6-phosphate enzymes. which means that none of the lysosomal enzymes get to the right place… HUGE problem.

52
Q

Both _____ and _____ stabilize lysosomes

A

cortisol and chloroquine

53
Q

_________ historically has been used as an anti-malarial drug.

A

Chloroquine

Histology (8 decks)

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