Chapter 8: Cytoplasmic Membrane Systems- Structure, Function and Membrane Trafficking Flashcards
(44 cards)
1
Q
DNA areas in euk vs prok
A
- euks: nucleus: specific region
- prok: nucleoid region: specific region
2
Q
What are the components of the nucleus?(6)
A
- Nuclear envelope
- nuclear pores
- nucleolus
- chromatin
- nuclear matrix
- nucleoplasm
3
Q
Nucleus components functions:
- Nuclear envelope
- nuclear pores
- nucleolus
- chromatin
- nuclear matrix
- nucleoplasm
A
- 2 concentric membranes, around the nucleus
- more of a nuclear pore complex: made up of 30 different nuclear proteins that are transport receptors. (Binds ligands). It moves molecules across the nuclear envelop. Importins: transports in to nucleus.Exportins: transports out.
- assembly of rRNA
- DNA + histones
- insoluble fibrous matrix with many functions
L> maintains nuclear shape
L> provides structure for the formation of chromatin loops (unpacked sections of chromatin) which are the areas of transcription.
L> DNA and RNA replication ..processing RNA aka transcribe it and then slice then translate. - cellular sap of nucleus
4
Q
The double membrane of the nucleus is continuous with?
A
- the endoplasmic reticulum
5
Q
Mitochondria:
- describe it
A
- oxidative metabolism
- double membrane
- has its own DNA
- outer membrane. Inner membrane, cristae and matrix……
- energy generator
6
Q
Nuclear pore complex? (NPC) ?(everything you know)
A
- RNA molecules + proteins move in both directions through this…mrna, rna, ribosomal subunits are made in the nucleus than exported…
-sRNA’s (splicing) move in both directions bc made in nucleus then assembled in cytoplasm with proteins then comes back in the nucleus for splicing. - NPC has app 30 different proteins called nuclear porins.
L>largely conserved between yeast and verts - nuclear localization signal on a protein
L> to locate the nucleus (NLS)
**so you can target them to go back - SV40: T antigen
L>particular….NSL set of 7 aa’s…best case they are positive charged aa’s…If you take one and replace it by a non polar aa (diff charge) the protein will not move into the nucleus…loses the NSL
**conversely if you take a non nuclear protein and put NSL aa chain on it- it will enter the nucleus.
7
Q
Chloroplasts?
A
- photosynthesis
- double membrane
- its own DNA
- outer m, inner m, thylakoid, grana, stroma and lamella
- *animals need photosynthesis to occur
8
Q
Peroxisomes aka
A
microbodies
9
Q
Peroxisomes:
- compartmentalization for ?
- oxidation of?
- where are these highly concentrated?
- plant version?
A
- peroxide-generating reactions
- oxidation of toxic substances
- high [] in liver and kidney cells
- glyoxysomes in plants =equivalent …enzymes that break down FA
10
Q
Peroxisomes:
- Zellweger syndrome?
- Adrenyleukodystrophy
A
- enzymes not transported inside aka can’t get rid of toxic substances….neurological, visual issues etc…death in infancy
- Long chain FA not transported inside; builds up levels….
L> treatment= diet, stem cell therapy; gene therapy
11
Q
Endomembrane System:
- BSP??
A
- biosynthetic secretory pathway
L> things are made in the cell and potentially secreted out
12
Q
Endomembrane System:
- what makes it up?(3)
A
- Endoplasmic Reticulum (ER)
- Golgi complex
- Transport vesicles
- *EMS is highly conserved…across many organisms they all have similar EMS
13
Q
Endomembrane System:
- Description about proteins?
A
- once they are made they can be shipped into the cytoplasm and rough to ER to be modified aka tagged then brought to the golgi which packages it and transports it via vesicles
Nucleus–>ER—>golgi–> PM
14
Q
Biosynthetic - Secretory Pathway
-explain it and what are the two types of secretion?
A
- proteins synthesized in ER
- modified by golgi
- transported to various destinations via constitutive secretion and regulated secretion.
15
Q
Biosynthetic - Secretory Pathway
-Constitutive secretion?
A
- discharged into the extracellular space in a continuous manner
- unregulated
- daily maintenance (ECM or PM) this is why its occurring
- contents are released from cell via vesicle but M proteins fuse with M
16
Q
Biosynthetic - Secretory Pathway
- regulated secretion?
A
- materials are stored in M-bound packages
- discharged only in response to stimulus
- specific roles in body’s maintenance homeostasis!
- ex: allergic rxn causing a load of histamines released need anti histamines…
ex: endocrine cells,neurone, pancreatic acinar cells, intestinal goblet cells
17
Q
Biosynthetic - Secretory Pathway
- enzymes for proxisomes are made?
A
in the cytosol via free ribosomes therefore do not need to go under all of this processing
18
Q
Endoplasmic Reticulum (ER): -two types?
A
- smooth ER
- rough ER
19
Q
Endoplasmic Reticulum (ER): - Smooth ER
A
- synthesized steroid hormones
- detoxification in liver cells
- sequestering Ca 2+ (collect) …ex muscle contractions.
-gonands, liver, muscle cells = lots of smooth er !
Ex: metabolizing drugs varies across genetically different backgrounds
20
Q
Endoplasmic Reticulum (ER):
-smooth ER
L> Benzo(a) pyrene?
A
- smooth er: sometimes you can have a fine compound but once it goes through the liver and smooth er it becomes carcinogenic
- body ttys to convert it into a water soluble compound for secretion but it becomes a diol epoxide. Then it is able to interact with DNA which can lead to mutations that cause cancer
- source of BP = charred meat on barbecue ……can form group 1 carcinogenic !
- *lungs cannot dilute this to lessen its carcinogenic effects but the rest of the body does.
21
Q
Endoplasmic Reticulum (ER): - rough ER?
A
- studded with ribosomes
- continuous with outer M of nucleus
- actively synthesizes proteins .
22
Q
Endoplasmic Reticulum (ER): - similarity between smooth and rough?
A
- BOTH synthesize lipids and cholesterol similarly but they have functional differences
23
Q
Endoplasmic Reticulum (ER):
- rough ER
L> blurb on function?
**ERAD
A
- ribosomes translate mRNA into protein which are than translocated to the ER
- signal on protein that it needs to be in the ER after synthesis either lumen or membrane
- after in there the signal sequence is taken off
- carbs all added and a new sew is added.
- Benefit of carbs: acts as a binging site for interactions with macromolecules. Helps protein fold properly into its conformation. If its not filed properly it will not function properly. IF this occurs it will be shipped to the cytosol from the ER and proteases will break it down in the cytoplasm. The process is called ER associated degradation ( ERAD)
24
Q
Ribosomes:
- focal point for?
A
protein synthesis
25
Ribosomes:
| - two types?
- M-bound: ribosomes make proteins to be shipped throughout the cell! (3 types)
-FreeL products released into the cytoplasm
L> ex: glycolysis enzymes, cytoskeleton proteins, problems that can be translocated into the mitochondria, chloroplast, peroxisomes, and peripheral proteins
26
```
Golgi Complex (GC)
- description ?
```
- flattened cisternae, vesicles and tubules
- modifies molecules made in the ER
- synthesis of complex polysaccharides
27
```
Golgi Complex (GC)
- CGN and TGN?
```
- Cis golgi network primarily shorts proteins
| - trans golgi network segregates proteins into different vesicles (PM or intercellular)
28
Give the break down of the structure of the golgi complex?
- trans-golgi network (TGN) is furthest away - vesicles bud off for final destination
- trans cisternae
- medial cisternae
- cis cisternae
- cis-Golgi network (CGN)
* *CIS= closest to the ER
* * ERGIC: vesicles merge for sorting vesicular tubule carriers from ER
29
Two models of golgi function?
1. Cisternal maturation model
| 2. Vesicular Transport model
30
Two models of golgi function:
| 1. Cisternal maturation model??
- each cistern physically moves from cis to trans golgi, changing composition as it is progress
31
Two models of golgi function:
| 2. Vesicular transport model?
- cistern remain in place but the internal cargo is moved via budding vesicle from CGN to TGN
32
golgi:
| - The cis golgi sorts?
- the proteins that just arrived. Check point! Can they go or should they be shipped back to ER. "Gate Keeper"
- The trans golgi segregates the proteins into different vesicles where they will be transported. (modified proteins)
- Modifications made in ER are changed around in the golgi. Within the golgi the key role is the assembly of carb parts again onto glycolipid any glycoprotein.
33
Which golgi model is more accepted?
- cisternal maturation model
- drug induced if ER is prevented from budding there is no golgi! Internal cargo moves to TGC with cistern i.e. it never leaves the cistera
* *golgi is usually established ER budding
34
Coated vesicles:
| - three types?
- COPI- retrograde direction (backwards) from trans---cis..cis--er. **rejected cargo is transported via this
- COPII - works in the direction of ER------Cis golgi
- Clathrin coated vesicles - moves materials from trans t endosomes, lysosomes and PMI.
35
Clathrin Vesicles??
- carries cargo from TGN to lysosomes
| - involved in receptor mediated endocytosis
36
COPII vesicles?
- mediate BSP from the ER-ERGIC-CGN
L> SAR 1 (protein....GTP binding) : regulates for nation
L> GTP binding protein
L> initiates vesicular formation and coat assembly
***sometimes ER resident proteins become present int eh coated vesicle but if escaped COPI will bring them back to ER.
37
COPI Vesicles?
- responsible for retrograde transport of proteins
L> golgi enzymes from TGN and CGN
L> ER enzymes from ERGIC and CGN back in new brunswick
- retrieval of ER molecular chaperons
L> contain aa (KDEL)
L>COPI vesicles contain M proteins with KDEL receptors (KKXX)
**ERMC have gone into a vesicle coated with COPII sent to CIS therefore it needs to coat back !
38
Lysosomes?
- hydrolyzing enzymes are tagged and transported to endosome or lysosome.
- role in organelle turn over
- formation of lipofuscin granules (two fates)
39
Lysosomes and endocytosis?
- needs to through BSP to get to cytoplasm via catherine
1. lysosomal enzyme (LE) is translated and transcripted to G
2. LE is tagged with M6P and attached to its mannose phosphate receptor.
3. transporting LE in catherin coated vesicles
4. removal of MPR
5. recycling MPR
6. LE goes into endosome/Lysosome
7. escaped LE are retrieved
40
Lysosomes and organelle destruction?
| L> what happens when depleted of nutrients.
- our cells will digest their own organelles if they are depleted of nutrients
41
Explain lysosome and organelle destruction!
1. organelle is engulfed by a phagophore(forming autophagosome)
2. a lysosome (transported from the golgi complex) binds to the autophagosome
3. Autolysosome (lysosome +organelle) two fates...it can discharge via exocytosis or the residual body goes on and forms a lipofuscin pigment granule(these build up in a cell as you age indicated an estimate of age)
42
Endosomes:
| - network of?
- tubules and vesicles
43
Two type of endosomes?
1. Early endosomes
L> near cell periphery, sorting station (back to PM or other destination )
2. Late endosomes
L> closer to nucleus, contain PM proteins for destruction
**when encounters vesicle from TGN becomes a functional lysosome
44
Endocytic Pathway :
| - Endocytosis?
- receptors
L>house keeping and signalling
- phagocytosis
L> phagolysosome
