Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Molecular and Cellular Regulation: Biosci 353 > Vesicular Transport > Flashcards

Vesicular Transport Flashcards

1
Q

How many divisions are involved in the synchronous chromosome replication and division of Drosphila?

A

13 divisions, which results in 6000 nuclei in a single cell. This is called the syncitium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are some methods of identifying cellular components?

A
  • GFP and confocal microscopy
  • Genomics and proteonomics
  • X-ray crystallography
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is gel elctrophoresis used for?

A

Visualising the protein expression in cells. Proteins are separated by charge and size, and individual dots can be isolated and sequenced by mass spectrometry to identify.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is GFP so useful in cellular studies?

A
  • it is intrinsically fluorescent
  • it fluoresces without a specialised chromophore
  • it can be attached to cellular proteins to make them visible (confocal fluorescence microscopy)

Especially useful for localisation studies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Why is Xray crystallography so useful?

A
  • size isn’t an issue
  • uses xray diffraction to determine structure via radiation pattern

Unfortunately it requires a crystalline protein, which can be difficult to obtain (low tech but conditions need to be extact for it to work)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does Ras control?

A

Cell-growth pathways

Hence often mutated permanently on in cancerous growths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does Ran control?

A

Nuclear transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does Rab control?

A

Vesicular transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the common feature of the small GTPase proteins

A

They act as switches
When GTP is bound it is in the ON state
When it is hydrolysed to GDP it is in the OFF state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are some examples of structures determined by X-ray crystallography?

A 
The ribosome (made mainly of RNA with associated protein)
RNA pol 2 (DNA => mRNA)
Photosystem 1 (main enzyme in photosynthesis - electron pump)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Novick, sec mutants. What is Class A?

A

Accumulation in - cytosol

Defective - transport into ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Novick, sec mutants. What is Class B?

A

Accumulation in - rough ER

Defective - budding of vesicles from rough ER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Novick, sec mutants. What is Class C?

A

Accumulation in - ER-to-Golgi transport vesicles

Defective - fusion of transport vesicles with Golgi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Novick, sec mutants. What is Class D?

A

Accumulation in - Golgi

Defective - transport from Golgi to secretory vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Novick, sec mutants. What is Class E?

A

Accumulation in - secretory vesicles

Defective - transport from secretory vesicles to cell surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How many types of SNAREs are there?

A

v-SNAREs - part of vesicles, fuse with following
t-SNARES - part of target organelle membrane, fuse with above
Fundamental in FUSION

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are Rab proteins?

A

GTP binding proteins
Involved in controlling vesicular transport
About 60 types in humans, 12 have been shown to be associated with specific membranes and forms of transport
Related to membrane TARGETING

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do Rab proteins attach?

A

C-terminal covalently bound lipids
This part of the molecule is non-conserved and provides variation that allows a myriad of specific targets
Monoclonal AB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 9 steps of secretory and endocytic pathways for protein sorting?

A

1 - Protein synthesis on ER-bound ribosomes. Co-translational transport of proteins into or across ER membrane

2 - Budding and fusion of ER-to-Golgi vesicles to form cis-Golgi

3 - Retrograde Golgi-ER transport

4 - Cisternal progession (cis to medial to trans)

5 - Retrograde transport from later to earlier Golgi cisternae

6 - Constitutive secretion

7 - Regulated secretion

8 - Sorting to lysosomes

9 - Endocytosis

Steps 5-9 don’t occur sequentially but are all possible courses of action

20
Q

COPI

A

Associated with retrograde transport (trans to medial to cis-Golgi to ER)

21
Q

COPII

A

Associated with ER to cis-Golgi transport

22
Q

Clathrin-coated

A

Used in endocytosis from cellular membrane to cytoplasm
Used in movement from Trans-Golgi to the Late Endosome
COPI and COPII are both types of clathrin coats also

23
Q

Waht are the 4 essential steps in Vesicle Transport?

A
  • budding
  • movement
  • tethering
  • fusion

Cargo selection is also involved prior to budding

24
Q

What is involved in the budding step?

A
  • coat proteins to bud the vesicle off
  • cargo receptors to select cargo
  • cargo can be transmembrane or bound to receptor
25
Q

What is involved in the movement step?

A

Motor proteins (kinesin, dynein, myosin) associated with the outside of the vesicle move it along the cytoskeleton (microtubules or actin)

26
Q

What is involved in the tethering step?

A
  • Controlled by Rab proteins (mechanism unknown - act somehow as a vesicular tether to the acceptor compartment)
27
Q

What is involved in the fusion step?

A

v-SNAREs on the vesicle recognise and bind to t-SNAREs on target membrane, and form a trans-SNARE complex, fusing the membranes.

4 SNAREs involed

28
Q

What are SNAREs?

A

SNAREs are a set of membrane proteins identified by Rothman using cell-free transport assays. (difficult to purify without other membrane presence)

Critical in vesicle FUSION

29
Q

Why are carbohydrate protein attachments different in individuals?

A

Enzymes progressively modify carbohydrate chains during anterograde transport through the Golgi - these enzymes can differ slightly between people - this is how ABO blood antigens come about

30
Q

What are some common components of SNAREs involved in synaptic transmission?

A

VAMP (v-SNARE)

Syntaxin and SNAP-25 (t-SNAREs)

31
Q

What amino acids are important in q-SNAREs (t) and r-SNARES (v)?

A

q-SNAREs - glutamine

r-SNAREs - arginine

32
Q

Which viral model is goos for membrane fusion?

A

HIV and Influenza. Mechanism of fusion for these molecules is well described, and the molecules (gp41 and HA respectively) are very structurally similare to SNAREs.

Both mechanisms are triggered by pH drops

33
Q

Where are the chromosomes in the nucleus?

A

Smaller chromosomes seem to be located significantly closer to the nucleus centre (independent of gene density)

34
Q

What are the nuclear contents?

A
  • DNA
  • Nucleosomes
  • Histone proteins
  • DNA pol
  • RNA transcriptase
  • Promotor proteins
  • RNA
  • RNA binding proteins
  • Splicing machineries
  • sn RNPs
  • Internal structures
  • Nucleosome
  • Ribosome factory
  • Nuclear lamins = nuclear membrane

There are no internal membranes, no tubulin, actin (controversial), no protein synthesis, no organelles

35
Q

Hoe large is the nuclear pore?

A

50x larger than a ribosome

36
Q

Be able to draw the nuclear pore complex and name components

A

-

37
Q

What makes up the nuclear envelope?

A

2 lipid bilayers

Is connected to the ER

38
Q

What can get through the nuclear pore complex?

A

Free diffusion of ions and small molecules

Receptor-mediated transport of proteins, RNAs, RNPs

39
Q

What are some important features of the nuclear pore complex?

A

8-fold symmetry
Kinked cytoplasmic filaments
Nuclear basket
Architecture is conserved from yeast to man
Made of ~30 Nup proteins/nucleoporins
Many have FG repeat segments (presumed unfolded and to interact with receptors, importins and exportins)
The central framework consists of 6 Nups - Nup 160, 133, 107, 96, 85, Sec13

40
Q

What sort of cargo is imported through the nuclear pore?

A
  • nucleotides to make DNA and RNA
  • amino acids to acylate tRNA
  • ribosomal proteins
  • snRNPs and histones
  • polymerases, promotors
  • nuclear lamins
41
Q

What sort of cargo is exported through the nuclear pore?

A
  • tRNAs
  • processed mRNA (NOT pre-RNA)
  • assembled ribosomal subunits
42
Q

Where is the ribosome assembled?

A

Large and small subunits are folded and assembled in the nucleus and then exported into the cytoplasm
Subunits are joined in the cytoplasm

43
Q

What is the capacity of the nuclear pore?

A

Mass flow of 80 million Da per second (equivalent to about 1000 molecules)
This occurs often against a concentration gradient
Mechanism still unclear

44
Q

How is the nuclear pore complex assembled?

A

Very unclear
Independent of DNA
Ran is centrally involved

45
Q

How does Ran control nuclear export?

A

System relies on asymmetric distribution of Ran GAP and RCC1 (a GEF in the nucleus)
Ran GAP is higher in the cytoplasm, which converts Ran into its inactive GDP form
RCC1 is higher in the nucleus and converts it to the active GTP form

GTP form mediates nuclear cargo export bound to the exportin 1 protein

Required to form Cargo complex - possibly provides energy for the crossing

46
Q

How is Ran involved in nuclear import?

A

Like export mechanism, relies on asymmetric distribution of GAP and GEF, resultinf in Ran GTP in nucleus and Ran GDP in cytoplasm

Importin complex is an alpha-beta dimer

Import complex falls apart in the nucleus after attack by Ran-GTP which binds to beta component. The beta component is freed in the cytoplasm when Ran is converted to GDP state, allowing the beta to bind another alpha-cargo complex.

Cargo have nuclear localisation signals - short basic protein sequences.

Molecular and Cellular Regulation: Biosci 353 (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions