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.
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
Transmembrane transport involves proteins called _____ ______ that transport specific proteins across a membrane into another compartment
2 major types of protein signals?
The largest intracellular compartment
The sorting signal sequence is usually removed by the enzyme one it reaches its destination. What enzyme?
both types of proteins sorting signals are recognized by a ____ _____
The nuclear envelope surround the __________.
A nucleopore contains a _____ _____ _____ composed of many types of proteins called _________
Nuclear pore complex
this signal sequence destines a protein to be imported into the nucleus
nuclear localization signals
Proteins containing a nuclear localization signal (imported) will be recognized by _______ that guide the protein through the nuclear core complex into the nucleus
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
The mitochondria has _ membranes.
The chloroplast has _ membranes. Name them
How does the mitochondria and chloroplast aquire their proteins?
imported. Genes encode for them (nucleus)
This protein import process occurs in peroxisomes and nucleoplasm
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
Plants convert stored fatty acids into sugars in the ______ cycle. The peroxisomes involved in this cycle are termed _________.
The organelle that synthesizes mitochondrial and peroxisome lipids
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
This kind of protein contains the LARGEST consectuive hydrophobic sequence and is transported by a the method co-translational translocation
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 ______
Signal recognition Particle (SRP)
This signal acts as a start transfer, and opens the aqeous pore to initiate translocation
A _____ region in a transmembrane protein is hydrophobic and stops further translocation
Name the 5 major functions of the ER
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
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?
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?
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)
Proteins are folding in the
c) a and b
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
This enzymes is found in the plasma membrane and flips only specific phospholipids to the cytoplasmic membrane
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 _____ ______
Peroxisome aquire their lipids by 2 ways
this organelle contains catalase and will convert excess hydrogen peroxide into water