Cell Organelles Flashcards
What kind of cells contain relatively more Rough ER?
Pancreatic exocrine cells
What is the luminal compartment of the ER called?
Cisternal compartment
Which organelle is larger in cells that make secreted protein?
Rough ER
Which part of a growing polypeptide directs it to the endoplasmic reticulum?
The signal sequence
What are the two main structural differences between the RER and SER?
RER: Elongated cisternae, studded with ribosomes
SER: Tubular cisternae, lacks ribosomes
What is the difference in function between the RER and SER?
RER: Protein synthesis for intracellular use or exportation
SER: Lipid synthesis, glycogen metabolism, detoxification, calcium regulation
What are the functions of the Golgi apparatus?
Modification of carbohydrates attached to glycoproteins and proteoglycans, poly/oligo-saccharide synthesis, synthesis of sphingomyelin and glycosphingolipids, packing/sorting secretory products
What happens to the Golgi apparatus during mitosis/meiosis?
It disassembles then reassembles in interphase
What is the purpose of a mannose-6 phosphate (M6P) tag?
It marks precursor proteins (acid hydrolases) that are destined for transport to lysosomes. Occurs in the Golgi.
Where do Clathrin-coated vesicles transport products to and from?
From the Golgi apparatus to lysosomes AND from the exterior of the cell to lysosomes
Where do COP-coated vesicles transport products to and from?
From one stack of the Golgi apparatus to another (COP1) AND from the endoplasmic reticulum to the Golgi apparatus (COP2)
What is the role of dynamin?
It surrounds the neck of the a budding vesicle and pinches it off.
What is the role of adaptins?
The mediate clathrin binding to a vesicle
Describe the main steps of the lysosomal sorting pathway.
- M6P is used to tag lysosomal enzymes
- Lysosomal enzymes bind to M6P receptor and the vesicle buds off
- M6P receptor is returned to the Golgi for recycling
How do lysosomes maintain an acidic environment?
Through ATP-dependent H+ pumps
What is the difference between a primary lysosome and a secondary lysosome?
Primary lysosomes are the storage sites for lysosome hydrolases. Secondary lysosomes form when a primary lysosome fuses with an endosome.
What is familial hypercholesterolemia?
Mechanism of cholesterol uptake is disrupted. Characterized by elevation of LDL usually due to defect in LDL receptors. High levels of LDL can lead to atherosclerotic plaques.
What are the functions of peroxisomes (microbodies)
Synthesis and degradation of hydrogen peroxide, Beta-oxidation of LCFAs, bile acid/cholesterol synthesis, and detoxification of alcohol.
Describe Zellweger Spectrum disorders.
Peroxisome biogenesis disorders. 12 genes are required for peroxisome synthesis. A defect in any of them can result in a disorder on the spectrum. The most serious is Zellweger Syndrome, which usually causes death within the first year.
Mutations in what part of mitochondrial DNA has been linked to over 200 disease states?
DNA encoding for mitochondrial tRNAs
