What causes wrinkles of aging?
Reduced production of collagen and elastin (p.79)
Cellular Biochemistry Questions
Answers + First Aid Page Number
What regulates checkpoints between phases of the cell cycle?
Cyclins, CDKs, tumor suppressors (p.74)
What is the shortest phase of the cell cycle and what phases are of variable duration?
Mitosis is shortest; G0 and G1 are of variable duration (p.74)
What is the order of subphases in Mitosis?
Prophase, Metaphase, Anaphase, Telophase (p.74)
What phases of the cell cycle compose Interphase?
G1, S, G2 (p.74)
Compare CDKs to Cyclins.
CDKs (cyclin dependent kinases) are constitutive and inactive; Cyclins are regulatory proteins that control cell cycle events, are phase specific and activate CDKs; In Cyclin-CDK complexes, both must be either active or inactivated for the cell cycle to progress (p.74)
Name 2 Tumor Suppressors.
1.) p53; 2.) hypophosphorylated Rb. Both normally inhibit progression from G1 --> S (p.74)
What is the function of the Rough Endoplasmic Reticulum?
Site of synthesis of secretory (exported) proteins and of N-linked oligosaccharide addition to many proteins. Contains free ribosomes where synthesis of cytosolic and organellar proteins occurs (p.74)
What is Rough ER in neurons called and what is its function?
Nissl bodies- synthesize enzymes ChAT, Ach, and peptide NTs (p.74)
Name two cell types that are rich in Rough ER.
1.) Mucus secreting goblet cells of the small intestine; 2.) Antibody secreting plasma cells (p.74)
What is the function of the Smooth Endoplasmic Reticulum?
Site of steroid synthesis and detoxification of drugs and poisons (p.74)
Name two cell types that are rich in smooth ER.
1.) Liver hepatocytes; 2.) Steroid hormone producing cells of the adrenal cortex (p.74)
Where does cell trafficking occur?
Golgi apparatus is the distribution center for proteins and lipids from the ER to the vesicles and plasma membrane (p.75)
What modification are made in the Golgi apparatus for cell trafficking?
1.) Modification of N-oligosaccharides on asparagine; 2.) Addition of O- oligosaccharides on serine and threonine; 3.) Addition of Mannose 6- phosphate to proteins for trafficking to lysosomes (p.75)
What is the function of endosomes in cell trafficking?
Sorting centres for material from outside the cell or from the Golgi; sends material to lysosomes for destruction or back to the golgi/ membrane for further use (p.75)
What is the pathology of I-Cell Disease?
Inherited lysosomal storage disorder. Failure of addition of mannose-6-phosphate to lysosome proteins causes enzymes to be secreted outside the cell instead of targeted to the lysosome (p.75)
What is the clinical Presentation of I-Cell Disease?
Coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes; often fatal in childhood (p.75)
Name the three vesicular trafficking proteins and their direction of trafficking.
1.) COPI: Golgi --> Golgi (retrograde) OR Golgi --> Endoplasmic Reticulum; 2.) COPII: Golgi --> Golgi (anterograde) OR ER --> Golgi; 3.) Clathrin: trans-Golgi --> lysosomes OR plasma membrane --> endosomes (receptor mediated endocytosis) (p.75)
What is a peroxisome?
A membrane enclosed organelle involved in catabolism of very long fatty acids and amino acids (p.75)
What is a proteosome?
A barrel shaped complex that degrades damaged or unnecessary proteins tagged for destruction with ubiquitin (p.75)
Describe the structure of a microtubule?
Cylindrical structures composed of a helical array of polymerized dimers of a and b-tubulin. Each dimer has 2 GTP bound. Microtubules grow slowly and collapse quickly (p.76)
What structures/ functions involve microtubules?
They are incorporated into flagella, cilia, mitotic spindles, and are also involved in slow axoplasmic transport in neurons (p.76)
Name 2 molecular motor proteins and their direction of transport.
1.) Dynein --> retrograde to microtubule (+ --> -); 2.) Kinesin --> anterograde to microtubule (- --> +) (p.76)
What is the function of molecular motor proteins?
To transport cellular cargo towards opposite ends of microtubule tracks (p.76)