1.2 Cellular Housekeeping, Cellular Metabolism and Mitochondrial Function Flashcards
What are some benefits of compartmentalization in cellular structure?
1) It keeps degrading or toxic enzymes or metabolites at high concentrations without damaging other structures in the cell.
2) Allows the creation of unique intracellular environments (e.g. low pH or high calcium) to permit efficient functioning of certain enzymes or metabolic pathways
What is the function of the rough endoplasmic reticulum and Golgi apparatus?
Synthesis of proteins that are destined for the plasma membrane or for secretion
What is the function of free ribosomes?
Synthesis of proteins that are bound for the cytosol
What is the function of the smooth endoplasmic reticulum?
Synthesis of steroid hormones and lipoproteins.
Modification of hydrophobic compounds into water-soluble molecules for export.
What is the function of a proteasome?
Degrade denatured or tagged cytosolic proteins.
In antigen presenting cells, the resulting short peptides are presented in the context of class I or class II major histocompatibility molecules to help drive the adaptive immune response.
In other cases proteasomal degradation of regulatory proteins or transcription factors can trigger initiation or suppression of signalling pathways.
What is the function of a lysosome?
Digest a wide range of macromolecules (including proteins, polysaccharides, lipids and nucleic acids) using enzymes. They breakdown aging intracellular organelles and kill and catabolise phagocytosed microbes.
What is the function of a peroxisome?
Break down very long-chain fatty acids, generating hydrogen peroxide in the process. They contain catalase, peroxidase and other oxidative enzymes.
What is the function of an endosome?
Transport internalized material to the appropriate intracellular sites
What is the cytoskeleton comprised of?
1) Filamentous actin (microfilaments)
2) Keratins (Intermediate filaments)
3) Microtubules
What is the function of the cytoskeleton?
1) Facilitate movement of organelles and proteins within the cell
2) Maintain cellular shape and intracellular organization, thus maintaining cell polarity
Why is cell polarity important particularly for epithelial cells?
In epithelium, the top of the cell (apical) and bottom and sides (basolateral) are exposed to different environments and have different functions. Loss of polarity could, for example, disrupt vectorial transcellular transport in the intestine or renal tubule.
What is the purpose of mitochondria?
1) Generate most of the adenosine triphosphate (ATP)
2) Serve as an important source of metabolic intermediates needed for anabolic metabolism
3) Site of synthesis of certain macromolecules (e.g. heme)
4) Contain important sensors of cell damage that can initiate and regulate programmed cell death (e.g. apoptosis)
Describe broadly the structure of a plasma membrane
Plasma membranes are fluid bilayers of amphipathic phospholipids with hydrophilic head groups facing the aqueous environment and hydrophobic tail groups interacting with one another to form a barrier to passive diffusion.
The bilayer is heterogenous in composition.
