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51 Cards in this Set

  • Front
  • Back
What determines the abundance and distribution of organelles in a cell?
the particular physiology needs of the cell, the function of the cell
Function and parts of ribosomes?
Synthesize proteins, small subunit binds to mRNA first, then large subunit binds
What are the functions of organelles?
Concentrate enzymatic rxns.
Segregate competing metabolic processes.
Segregate harmful products from the rest of the cell.
What are the functions of these organelles?
segregates replication and transcription
concentrates energy-producing rxns
What is the function of these systems?
Endocytotic sys.
Secretory sys.
-Controls the absorption and the fate of ingested materials
-organizes the synthesis, transport and quality control of carbohydrates,proteins, nucleic acids and lipids
Function of monitoring mechanisms?
assure quality control of all cell products, neutralize toxic substances and recycle intracellular signals
What is process/sequence of exocytosis?
(primarily the production and export of proteins)
ER -> Golgi -> Secretory vesicles -> exterior of cell
* sometimes small proteins are exported directly, no vesicle necessary.
What is process of endocytosis?
Cell exterior > early endosome > late endosome> lysosome or golgi to ER

Some materials are recycled to the exterior of the cell or to the golgi and ER.
What kind of proteins are synthesized for intracellular use ?
Soluable and nuclear enzymes, proteins to replace/repair organelles, new membrane proteins.
whats the sequence of events for synthesizing intracellular proteins?
ER > golgi > cytosol
ER > cytosol
or made in cytosol (free polyribosomes make protein in cytosol)
Where are proteins synthesized?
Free ribosomes, make intracellular proteins (soluable and nuclear enzymes, replace/repair proteins, some plasmalemma proteins)
Ribosomes on RER, make secretory, lysosomal, and basic plasma membrane proteins
Where are lipid components of new plasma membrane made?
What targets proteins to their destination?
Signal peptides
Basophilia stain properties
Basic (+) dyes like hematoxylin (blue) dyes basophilic (-) substances like RNA, DNA, glycosaminoglycans
Acidophilia (eosinophilia) stain properties
Acid (-) dyes like Eosin (orange G). Dyes + substances like cytosolic proteins, collage, hemoglobin
What are the steps of synthesizing secretory proteins across the ER?
. Note the “signal sequence” attached to the end of the nascent polypeptide chain.
2. This signal sequence directs the ribosome to bind the Signal Recognition Protein (SRP) and move to the ER membrane..
3. The SRP binds to the SRP receptor on the ER membrane and to GTP.
4. These events open the translocon to receive the polypeptide chain. Both the SRP and its receptor hydrolyze GTP and dissociate from the transcolon.
5. The signal sequence is cleaved off by the adjacent signal peptidase.
Where can you find lots of Rough ER (wall to wall)?
In cells that secrete/make lots of proteins.
What is transcription, translation, codons, tRNA, mRNA, and rRNA?
transcription -RNA synthesis
Translation - protein synthesis
codons - combos of three bases that code for specific amino acids
tRNA - transfer RNA, brings specific AAs to ribosome/mRNA complex to be made into protein
mRNA - messenger RNA,The template for the amino acid sequence of a unique protein; read by ribosome
rRNA - ribosomal RNA, involve with ribosome in synthesizing proteins
where are subunits of ribosomes made?
Where can you find polyribosomes?
attached to ER or free in cytosol
development of antibiotics was enabled by knowledge what type of synthesis?
protein synthesis in prokaryotes
what happens to a protein made in the rough ER?
RER ribosomes sit on membrane, when make protein, enters the lumen, forms its configurations, get glycosylated, proteins may remain in lumen, or travel to Golgi and transported by vesicular transport to extracellular space or into lysosomes (hydrolases), or into plasma membranes
What function does the signal sequence provide?
know the exact address of proteins once compelete, where they are bound for, based on the signal peptide, which can be as short as 3 peptides or as long as 80.
What enables self-assembly of a protein into its 3d structure?
Signal patches
What happens to misfolded proteins made in ER?
Accumulate in the cytosol or the lumen of the rough ER.
Name two diseases that involve protein misfolding in their etiology.
Alzheimer’s Disease, get tangles and extracellular amyloid plaques, and Mad Cow disease
What proteins may assist in the folding process of proteins?
Chaperone proteins.
What is rough ER, and what are its roles?
RER is studded with ribosomes and is engaged in protein synthesis. It typically has a lamellated appearance—like stacks of pita bread.
Protein synthesis, quality assurance (using quality control mechanisms eg chaperone proteins), endolysomal system, (proteosome pathway).
The glycosylation of proteins (acts as destination signal tag).
What is a disease is caused by problem with folding of protein, stays in ER, so ER get swollen with accumulated misfolded trypsin
a-1 anti-trypsin deficiency disease
What role do microtubules fill for the rough ER?
microtubules responsible for maintaining the structure of RER, it would collapse without microtubules
what directs completed protein in the cytosol?
singal peptides
what are some destinations for proteins made in the cytosol?
nucleus, chloroplast, mitochondria (has to unfold), peroxisome, ER
what are the important roles for smooth ER and the location where these occur?
Glycogen metabolism (liver and muscle)
Detoxification using p540 complex (liver)
Calcium storage (skeletal and cardiac muscle)
Lipid metabolism (all cells)
Steroid metabolism (adrenal glands, ovaries, testis)
What are the two faces of the golgi apparatus?
What is its role?
Cis and trans
Processes and sorts secreted and membrane proteins
Describe the Golgi Complex and its function
Membranous cisternae with a variety of enzymes, which are involved in terminal glycosylation, phophorylation, and sulfation of proteins, proteoglycan synthesis, and sorting of all these proteins to their final destinations (eg cell memb, secretory granuals, lysosome).
Describe sequence of passing through the golgi
Protein-laden vesicles arrive from ER at the CIS golgi, transverse several intermediate cisternae, and then are sorted for their final destination in the Trans-golgi network/side (TGN)
Give an example of protein sorting/targeting.
Receptor/ligand process. Lysosomal enzymes get attached to mannose-6-phosphate tag in the golgi. A mannose-6-phosphate receptor in the TGN recognizes the tag and proteins are delivered in cathrine-coated vesicles to the late endosome/lysosomal compartment.
What might lots of Golgi in a cell indicate about that cell?
Secreting lots of materials, proteins.
How are vesicles transported from the ER to the cis Golgi network?
Microtubules with their motor proteins move along clusters of vescicles.
What does COP stand for? What is the function of the COPI and COPII coats?
Help direct vesicles to destinations
COP = coat protein complex, they are specific signal "address" peptides. COPI directs vesicles back to the ER from the Golgi, COPII directs them to the Golgi from the ER.
Role and characteristics of Mitochondria
Produce ATP via Kreb's cycle, Electron Transport Chain and ATP synthase. Has 4 domains created by inner and outer membranes. Inner membrane, surrounding the matrix, has cristae to increase surface area. Mitochondria have own DNA, which codes from some of its own rRNA, mRNA, and tRNA.
Can divide independently of the host cell.
Amount of ATP created by one mole of glucose?
36-38 moles of ATP
What do plasma cells do?
Make antibody proteins at about 2000 per second, live about 4-5 days, have wall to wall ER.
Compare constitutive and regulated secretion
constitutive is unregulated and occurs all the time. In Regulated secretion the secretory vesicle waits in cytoplasm until signal (eg hormone, NT) is received that contents are needed.
Golgi functions
-Limited glycosylation (&/or modification) of proteins
-Synthesis and modification of polysaccharides
-Sulfation of proteins, oligosaccharides
-Phosphorylation of lysosomal enzymes
VERY IMP : Regulation of protein traffic: tagging, targeting and sorting
Smooth ER functions
Synthesis of:
-membrane lipids in essentially all cells (eg phospholipids, cholesterol, glycolipids)
-synthesis of steroid hormones (ovary, testis, adrenal gland)
-contains enzymes for gluconeogenesis and glycolysis (liver, skeletal muscle)
-Drug metabolism and detoxification (cytochrome p540 enzymes)
-Sequestration and release of calcium (cardiac and skeletal muscles)
Give overview of oxidative phosphorylation
Using fatty acids (derived from lipid stores) and pyruvate (derived from the breakdown of sugars through glycolysis) as starting material, acetyl-CoA is produced and fed into the Kreb's cycle, oxidized to yield high energy electrons which are then passed down the electron transport chain located on the inner mitochondrial membrane. The energy derived from this reaction is used to pump protons across the inner membrane, creating a gradient which is relieved by the movement of protons through the ATP synthase complex of the inner membrane leading to the production of ATP.
Characteristics of Peroxisomes
Found in all eukaryotic cells
most abundant in liver and kidney, membrane-bound, non-descript bodies, 0.2-1.0mm diameter, contain ~ 50 enyzmes
Roles of Peroxisomes
fatty acid oxidation (incl. long chain [>20 CH2] fatty acids, e.g. beta oxidation)
detoxification of ethanols, phenol, formaldehyde
lipid biosynthesis, e.g. plasmalogens (myelin phospholipid)
break down free radicals ?
Role of Proteosomes
Proteosomes degrade endogenous proteins (those synthesized within the cell) and smaller signal peptides, e.g.., transcription factors, cell cycle cyclins, and importantly, misfolded proteins. Proteosomes are the obsolete message shredder of the cell.
What is the most common phospholipid in the membrane?