-
Lumen:_________________
interior of organelles
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Sorting signal in a protein functions to? If a protein lacks a sorting signal then what happens?
- the signals purpose is to make sure the proper protein goes to the proper organelles.
- The absence of the signal means the protein will remain in the cytosol.
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Proteins with a sorting signal will be deliver by one of three mechanisms. Name them.
- 1) Gated transport
- 2) transmembrane transport
- 3) Vesicular transport
-
In gated transport of a protein, the protein will pass through a ____ ______ ____ that act as a elective gate for large molecules. Because it is a gate, smaller molecules may simpoly diffuse through.
nuclear core complex
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Transmembrane transport involves proteins called _____ ______ that transport specific proteins across a membrane into another compartment
protein translocators
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2 major types of protein signals?
- singal sequence
- signal patch
-
The largest intracellular compartment
cytoplasm
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The sorting signal sequence is usually removed by the enzyme one it reaches its destination. What enzyme?
singnal peptidase
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both types of proteins sorting signals are recognized by a ____ _____
sorting receptor
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The nuclear envelope surround the __________.
nucleoplasm
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A nucleopore contains a _____ _____ _____ composed of many types of proteins called _________
- Nuclear pore complex
- nucleoporins
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this signal sequence destines a protein to be imported into the nucleus
nuclear localization signals
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Proteins containing a nuclear localization signal (imported) will be recognized by _______ that guide the protein through the nuclear core complex into the nucleus
importins
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Substances to be exported have ____ _____ signals that are recognized by ______ that guide the substance through the nuclear core complex into the cytosol.
-
These structures give shape and stability to the nuclear envelope and form structural links between the nuclear envelope and chromatin
intermediate filaments and protein subunits called nuclear lamins
-
this actions caused the depolymerization of the nuclear lamina. The nuclear envelope fragments (prophase)
phosphorylation of lamins
-
this process results in the fusion of the nuclear envelope and ER fragments in early telophase
dephosphorylation of lamins
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The mitochondria has _ membranes.
2
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The chloroplast has _ membranes. Name them
- 3
- inner membrane
- outer membrane
- thylakoid membrane
-
How does the mitochondria and chloroplast aquire their proteins?
imported. Genes encode for them (nucleus)
-
This protein import process occurs in peroxisomes and nucleoplasm
post-translational translocation
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Imported mitochondrial proteins have one of four destinations
- 1) matrix space
- 2) outer membrane
- 3) innner membrane
- 4) intermembrane space
-
The cellular organelle does not contain DNA or ribosomes, found in all eukaryotic cells, a single membrane, and performs oxidase reactions
peroxisome
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Plants convert stored fatty acids into sugars in the ______ cycle. The peroxisomes involved in this cycle are termed _________.
- glyoxalate cycle
- glyoxysomes
-
The organelle that synthesizes mitochondrial and peroxisome lipids
ER
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2 kind of ribosomes
free floating ribosomes and membrane-bound ribosomes
-
True/false: A free ribosome contains signal sequences
false. The free floating lacks the sequence. Free floating in cytosol by default.
-
Membrane-bound ribosomes are bound to which surface of the ER?
cytosolic surface of the ER
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This kind of protein contains the LARGEST consectuive hydrophobic sequence and is transported by a the method co-translational translocation
membrane-bound ribosome
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True/false: ER proteins are transported by the mechanism co-translational transport.
False. Yes some proteins are translated by this method, but some are also imported via post-translations translocation.
-
This particle binds to the ER sequence once it emerges from the ribosome, and pauses translation. Then binds to the _____ receptor in the ER membrane. This is a ______
- SRP
- Signal recognition Particle (SRP)
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This signal acts as a start transfer, and opens the aqeous pore to initiate translocation
ER signal
-
A _____ region in a transmembrane protein is hydrophobic and stops further translocation
alpa-helical
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Name the 5 major functions of the ER
1)
2)
3)
4)
5)
- 1) site of production for all transmembrane proteins and lipids in cellular membrane
- 2) synthesis of mitochondrial and peroxisome lipids
- 3) site of protein synthesis: a) destined to be secreted b)delivered to the lumens of ER, GA or lysosome
- 4) Ca++ ions are stored in the smooth ER: the release of the ions finalize a muscle contraction
- 5) glycolsylation of proteins made in the rough ER
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This enzyme degrades the protein signal
singnal peptidase on the lumenal side of the ER membrane
-
A double-pass transmembrane protein contains 2 signals. What are they?
- start-transfer sequence
- stop-transfer sequence
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Glycolsylation of proteins made from the rough ER (this is a major function of the ER) can NOT involve which amino acid in the N-linked oligosaccharide?
Proline
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This specialized lipid molecule in the membrane holds the precursor oligosaccharide before it is transfered to the protein. This molecule is called ______. The sugar is transported via an enzyme ____________ that is membrane bound; transfers the oligosaccharide to the target amino acid in the _____ _____ (side of ER membrane)
- Dolichol
- oligosaccharide transferase
- ER lumen
-
Proteins are folding in the
a) lumen
b) cytosol
c) a and b
d) nucleoplasm
c) both lumen and cytosol
-
In the lumen, a improperly folded protein is exported to the ______ for degradation by the ______
-
These 2 important lipids are made from the ER on the _______ side of the ER membrane.
-
this phospholipid translocator is found in the ER membrane for symmetric growth
scramblase
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This enzymes is found in the plasma membrane and flips only specific phospholipids to the cytoplasmic membrane
flippase
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Lipids move from the ER to the mitochondria via an enzyme called the __________________________________ in the cytosol.
phospholipid exchange protein
-
Phosplipids move to the Nuclear membrane via _____ ______
lateral diffusion
-
Peroxisome aquire their lipids by 2 ways
1)
2)
-
this organelle contains catalase and will convert excess hydrogen peroxide into water
peroxisome
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