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Fundamentals Of Living Cells > Lysosomes > Flashcards

Lysosomes Flashcards

1
Q

What is the key function of lysosomes?

A

To carry out digestive, hydrolytic reactions

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2
Q

Give some examples of enzymes found in lysosomes and what molecule they break down

A 
Proteases (proteins)
Lipase (lipids)
Glycosidases (carbohydrates)
Nucleases (nucleic acids)
Phosphatases (phosphates)
Sulfatases ( sulfates)
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3
Q

What are the conditions like inside the lysosome?

A

Acidic (pH4-5)

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4
Q

What does heterogenous contents mean?

A

Lots of different molecules inside

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5
Q

Give examples of membrane proteins found in lysosome membranes

A 
V-ATPase
Ion channels
Cholesterol transporters
Sugar transporters
Nucleoside transporters
Amino acid transporters
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6
Q

Give examples of molecules found on the lysosome membrane

A

Small GTPases
Tethering factors
SNAREs

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7
Q

What is a SNARE responsible for?

A

The final fusion process in the residue targeting process

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8
Q

What does V-ATPase do?

A

Pumps proteins into the lysosome (to make it acidic)

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9
Q

How do lysosomes move around the cell and what must the have to facilitate this?

A

Microtubules so must contain motor signals to attach to the micro tubules

Also signalling complexes ( involved in immune response and metabolic signalling)

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10
Q

Where are transcription factors regulated?

A

On the surface of lysosomes

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11
Q

What cell contains melanosomes and what is the clinical feature when defective?

A

Melanocyte- ocular and Cutaneous hyperpigmentation

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12
Q

Give the features of melanosomes

A
  • Very high conc of melanin

- Formed in a four-step process

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13
Q

Once formed where are melanosomes transported to?

A

Keratinocytes

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14
Q

How are extracellular substrates delivered to the lysosome?

A

Endocytosis
Fluid phase endocytosis of molecules and lipoproteins (inducts receptor- mediated endocytosis)
- phagocytosis of small particles (> 50 micrometers)

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15
Q

How are intracellular substrates moved around the lysosome?

A

Microautophagy
invagination
Macroautophagy
Selective protein transport

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16
Q

What does microautophagy mean?

A

Self eating

17
Q

What does invagination mean?

A

Where budding takes place into the lysosomes

18
Q

How does macroautophagy work?

A

Cytosol or organelles wrapped in the ER membrane which then fuses with the lysosomal membrane

19
Q

What group of molecules takes part in receptor-mediated endocytosis?

A

Low-density lipoproteins

20
Q

Give the steps of phagocytosis

A

1- particle binds to the cell surface
2- particle is engulfed (plasma membrane wraps itself around the particle - forms a phagosome)
3-lysosome fuses with the phagosome (phagolysosome)
4-digestion

21
Q

What gets broken down in phagocytosis?

A
  • Bacteria
  • dead cells
  • ageing blood cells (B-cells, RBCs)
22
Q

Are macrophages able to pick up particles bigger than themselves?

A

Yes

23
Q

Give the specialist names for the autophagy of mitochondria

A

Mitophagy

24
Q

Give the specialist names for the autophagy of peroxisomes

A

Pexophagy

25
Q

Give the specialist names for the autophagy of ribosomes

A

Ribophagy

26
Q

Give the specialist names for the autophagy of lipid droplets

A

Lipophagy

27
Q

Give the specialist names for the autophagy of chloroplasts

A

Chlorophagy

28
Q

Give the specialist names for the autophagy of infectious particles

A

Xenophagy

29
Q

How does HIV deliver its virus?

A

Binds directly with the cell membrane

30
Q

How does influenza deliver its virus

A

Taken up by endocytosis and the drop in pH means that the endosomal and viral membranes break, releasing the viral contents

31
Q

How does polio and adenovirus deliver its virus?

A

Endocytosis

32
Q

What are the steps in the secretory pathway?

A
  • the mannose sugar is added in the Golgi body
  • the sugar is recognised by the MGP receptor
  • the receptor/sugar complex forms a clathrin-coated pit (and consequently a Clathrin coated vesicle)
  • this vesicle then carries the complex into the lysosome
33
Q

What causes most lysosomal storage disorders?

A

The lack of an enzyme in the lysosome which leads to the accumulation of a substrate

34
Q

What can mutations in lysosomal hydrolayses cause?

A

Substrate accumulation

35
Q

What does I cell disease mean?

A

No lysosomes are made so nothing can be digested

36
Q

What are the symptoms of I cell disease?

A

Skeletal abnormalities
Developmental delay
Enlarged liver and spleen

37
Q

What causes death (usually) from I cell disease?

A

Pneumonia or congestive heart failure

38
Q

What is I cell disease caused by?

A

A deficiency of UDP-N (acetylglucosamine)

39
Q

What does mutations in the M6P tag in the golgi cause?

A

Persistant stuttering

Fundamentals Of Living Cells (41 decks)

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