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Neuroscience > Molecules to cells > Flashcards

Molecules to cells Flashcards

1
Q

What occurs to the nuclear envelope during the cell cycle?

A

It is disassembled and later reassembled via phosphorylation and dephosphorylation of nuclear pore proteins and lamins.

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2
Q

Origin of nuclear envelope and ER

A

Invagination of the plasma membrane into the cytosol

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3
Q

main difference between mitochondria, chloroplasts and golgi, ER and lysosomes.

A

mitochondria and chloroplasts arent part of the vesicular transport network

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4
Q

Co-translational translocation

A

Process by which proteins are threaded across the ER membrane during polypeptide synthesis

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5
Q

Main property of ER signal sequence

A

Made up of string of hydrophobic amino acids

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6
Q

Main property of Nuclear localisation signal sequence

A

made up of string of basic amino acids

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7
Q

stop-transfer sequence

A

signal on integral membrane proteins which enables them to be integrated into the membrane

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8
Q

ER targeting signal

A

Signal sequence on proteins which enables them to be sent to the ER.

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9
Q

What do N-terminal signal sequences, stop-transfer sequences and signal-anchor sequences all have in common?

A

Made from hydrophobic amino acids, which makes them all recognizable by Sec61 complex

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10
Q

protein modifications at ER

A

1) cleavage of signal sequence
2) Disulphide bond formation
3) glycosylation

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11
Q

Protein disulphide isomerase

A

catalyses disulphide bond formation inside the ER lumen and ensures correct and appropriate bonds form.

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12
Q

Glycan

A

oligosaccharide present in ER lumen which modifies proteins by N-linked glycosylation

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13
Q

Dolicol

A

Lipid donor which provides an anchor for preformed N-linked glycans at the ER membrane

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14
Q

N-glycosidic bond of N-glycosylation

A

Carbon atom of first N-acetylglucosamine sugar of glycan to the nitrogen atom of asparagine

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15
Q

co-translational translocation

A

when a protein is translocated whilst still being synthesised

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16
Q

BiP

A

Heavy chain binding protein that acts as a chaperone using ATP to promote protein folding

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17
Q

Calnexin

A

ER chaperone that specifically assists in folding of N-glycosylated proteins

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18
Q

Scramblases

A

Enzyme that mediates flip-flopping of newly made lipids from cytosolic side of ER membrane to luminal side.

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19
Q

if you remove the KDEL retention signal from the ER resident protein BiP it will be:

A

secreted from the cell

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20
Q

If you add a KDEL signal to the C-terminus of a secretory protein like insulin it will be:

A

Retained in the ER

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21
Q

What is a key function of the cis-golgi?

A

Protein sorting

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22
Q

Examples of proteins which are secreted unconventionally

A

FGF2

IL 1β

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23
Q

What sorts cargo entering the cell?

A

the endosome

24
Q

What does the endocytic pathway do?

A

Deliver lipids and proteins to endosomes so they can be re-used

25
Q

Pinocytosis

A

Non-selective uptake of fluid and small particles by endocytic vesicles

26
Q

During LDL endocytosis, what occurs to the receptor following uptake in the endosome and why?

A

It dissociates from the LDL due to an acidic pH. it is then recycled to the cell surface.

27
Q

Addition of a mannose-6-phosphate signal to a protein will result in it being:

A
  • Retained at the ER
  • Sorted to secretory vesicles
  • Trafficked to the lysosome
28
Q

Phagocytosis

A

Uptake of large particles and microorganisms by specialised cells such as macrophages

29
Q

Autophagy

A

removal of obsolete parts of the cells and damaged organelles.

30
Q

what enzyme catalyses the fusion of autophagosomes with lysosomes?

A

SNARE proteins

31
Q

flippases

A

enzymes localised in golgi which selectively redistribute lipids in order to create specific phospholipid asymmetry across the bilayer

32
Q

Peripheral membrane proteins

A

proteins associated with the plasma membrane via binding to an integral transmembrane protein

33
Q

What is the route of protein destined for the plasma membrane?

A

ER -> golgi -> plasma membrane

34
Q

Common features of mitochondrial signal sequences

A

High content of Arg and Ser/Thr

Tendency to form amphiphillic alpha helices

35
Q

Congenital lactic acidosis

A

inherited metabolic disorder causes by a point mutation of residue 10 of pyruvate dehydrogenase subunit E1α, resulting in inefficient import of the pyruvate dehydrogenase complex causing reduced levels of PDH.

36
Q

Precursor of insulin

A

preproinsulin

37
Q

Types of preproinsulin mutation

A

Arg to Cys/His

Ala 24 converted to Asp

38
Q

Arg to Cys/His preproinsulin mutation

A

Prevents signal sequence interacting with Sec61 translocon.

Protein accumulates in cytosol causing gradual aggregation and death of pancreatic beta cells.

39
Q

Mutation which causes early onset diabetes

A

Ala24 to Asp

40
Q

Ala24 to Asp preproinsulin mutation

A

Inhibits cleavage of signal sequence causing improper folding causing ER stress due to accummulation in ER lumen.
Blocks export of wild type insulin from ER.

41
Q

Mutation which causes late onset diabetes

A

Arg to Cys/His

42
Q

mylolactone is a polyketide toxin which acts to inhibit the :

A

Sec61 translocon

43
Q

70% of cases of CF is caused by which mutation

A

The loss of a phenylalanine at residue 508 of CTFR - functions as a Cl- pump.

44
Q

Molecular chaperones

A

Help proteins to fold correctly and prevent them from aggregating

45
Q

BiP in the ER lumen is an example of a…

A

Molecular chaperone

46
Q

What happens when a molecular chaperone is bonded for a prolonged period of time?

A

Causes mutant protein to be recognised as misfolded

47
Q

What happens to misfolded proteins retained at the ER

A

They are eventually degraded by a ER associated degradation

48
Q

Proteosomes and ubiquisination occurs within the ER lumen. TRUE/FALSE

A

Not present in ER lumen.

Only occurs in cytosol

49
Q

THe most common form of CF is the result of a mutation that prevents

A

CFTR protein trafficking out of the ER

50
Q

Effects of carbamazepine

A

Enhance the proteasomal and autophagic disposal of the α1-AT Z mutant - reducing the proteotoxic load on cells

51
Q

Ways membrane bound organelles can import proteins

A

nuclear pores
translocation across membrane
vesicular transport

52
Q

What is the role of adaptins?

A

Bind cargo receptors during formation of a transport vesicle

53
Q

CM retention disease

A

preChylomicrons accumulate in the ER and are unable to reach the golgi

54
Q

What causes chlomicron retention disease?

A

Defective Sar1 GTPase

55
Q

what increases the risk of alzheimers disease

A

Cleavage of APP producing large and long amounts of A beta peptide

56
Q

potential therapies for AD

A

Stop or reduce Aβ prod.

Reverse Aβ aggregation

Neuroscience (22 decks)

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