Maintenance of metabolic equilibrium within an organism... compensates for disrupting changes and keeps cell stable/functional
How does glucose uptake work? (metabolite homeostasis)
-needs to be taken up from blood plasma into cell before metabolization. -polar molecule, cannot pass through hydrophobic plasma membrane, needs specialized transporters
-GLUT 1, GLUT 2, GLUT 3, GLUT 4 most important in glucose homeostasis
What are the two types of glycolysis and where are they located?
Aerobic glycolysis- cytosol, yields 34-36 ATP
Anaerobic glycolysis-in RBC
Oxygen controls utilization of chemical energy within glucose
What is gluconeogenesis?
Synthesis of glucose from pyruvate when blood glucose levels are low & glycogen stores are depleated
What is protein homeostasis?
Proper folding, expression, transport, and clearance of proteins -chaperones and enzymes help fold newly synthesized proteins -translocation machineries, proteasomes, autophagic activities help localize/degrade proteins
Know- Tom 20 and Tom 22 (receptors on mitochondrial surface) Tom 40 channel translocates preproteins across outer membrane
What does protein homeostasis on the transcriptional level refer to?
Transcription factors-regulate gene transcription across chromosome, have DNA binding domain, can promote/repress transcription of target genes... regulates expression/inhibition of protein synthesis
What are the most important post-translational protein modifications?
Acylation, Carboxylation, Phosphorylation, etc. See Table 4.2
What is a zymogen?
An inactive enzyme precursor
How do cell membranes help maintain homeostasis?
-Control what substances enter/leave cells
-enclose toxic materials
-allow food/H2O/waste exchange to stay alive
***The integrity of the cell membrane is important
What do glucose transporter do?
Facilitate transport of glucose and other sugars (galactose, fructose) in & out of cells along the sugar concentration gradient
What is Autophagy? (Autophagocytosis)
Basic catabolic mech, degradation of dysfunctional cell components... ensures synthesis, degradation, and recycling of such components. (lysosomes)
What occurs in the mitochondrial matrix?
Beta-oxidation of fatty acids
Storage of Ca2+
Mitochondria maintain homeostasis by _________
Fusion-mixes contents of partially damaged mitochondria
Fission-creates new and removes old mitochondria... facilitates apoptosis
What is proteolysis?
Controls protein degradation via intracellular proteolytic control, degrades by using lysosomal and proteasomal degridation
How is Proteolysis controlled extracellularly?
Proteins are degraded by extracellular proteolytic enzymes, often secreted as zymogens
What is Fanconi-Bickel syndrome?
GLUT2 glucose transporter deficiency
Stunted growth, hepatomegaly, hypoglycemia between meals/hyperglycemia post meal, rickets
Insulin secretion is low, glucose not released from liver in fasting state
Tx- ingestion of frequent small meals, avoid galactose, electrolytes
How does GLUT2 work?
Allows bidirectional transport of glucose depending on glucose concentration
High capacity but low affinity for glucose, acts as glucose sensor
What is drug-induced lupus erythematosus?
Genetic mutation in enzymes that carry out acetylation
Slow rate of drug acetylation, longer half-life of drugs, which are converted to toxic byproducts, triggers antinuclear antibodies