Regulation of Metabolic Pathways Flashcards
How are pathways interconnected?
- They have common metabolites that participate in both
- They have endparts that are important for the progression of other pathways
What pathways does glucose-6-phosphate participate in?
- Glycolysis
- Pentose-Phosphate pathway
- Polysaccharide synthesis
What is the Pasteur effect?
- A slowing or complete cessation of alcoholic fermentation in the presence of oxygen
- Glucose utilization in yeast is dependent on the presence or absence of oxygen
What does yeast do in the absence of oxygen?
Converts glucose into CO2 and alcohol in order to make ATP
What does yeast do in the presence of oxygen?
The end product can be used in the TCA cycle; utilized for something else
Yeast are __________ microorganisms
Facultative; can live with or without oxygen
How do cells maintain a dynamic steady state?
They maintain an amount of ATP that is necessary for energy utilization based on the energy source
Give two examples of how cells allocate nutrients for the maintenance of dynamic steady state levels?
- Blood glucose (glucose utilization)
- Fat storage (fatty acid mobilization)
What can stem cells become through cellular differentiation?
Any type of blood cells
What is the difference between stem cells and RBCs?
- RBCs do not contain a nucleus or a mitochondria
- Stem cells do; they can utilize nutrients using all of their organelles
What type of energy generation is used in RBCs?
Anaerobic because they do not have a mitochondria
What does tissue repair require?
- Energy
- Biosynthetic precursors
What nutrient source do neurons depend on?
- Entirely depend on glucose
- Because they do not have a storage capacity of nutrients
What do neurons use in ketosis?
Ketones (rare)
What do cardiac myocytes depend on in terms of nutrients?
Fatty acids
What is the first point of enzyme regulation?
Extracellular signals
How can transcription factors be regulated? (2)
- By phosphorylation or dephosphorylation
- By interacting with other proteins or transcription factors, which promotes regulation
In what ways can RNA be regulated?
- Stability
- Translation
If mRNA is stable, will it automatically be transcribed?
No
What is protein stability?
How long a protein is maintained in the cell (half-life)
What are cyclins? How are they regulated?
- Proteins that are important for cell cycles
- Synthesized and degraded depending on their requirement, which depends on the state of the cell
When do cells synthesize proteins? When do they degrade them?
- Synthesize: whenever they want
- Degrade: when they are not needed anymore
How does enzyme localization regulate enzymes?
- Enzymes might not be functional outside of an organelle (ex: mitochondria)
- If cells do not have an organelle, they can lack specific enzymes (ex: mitochondria)
Which 6 methods regulate levels of enzymes? Can it be measured?
- Yes
1) Extracellular Signals
2) Transcriptional Regulation
3) mRNA Stability
4) mRNA translation
5) Protein stability
6) Enzyme localization
What 4 methods regulate the activity of enzymes?
1) Changes of levels of substrate
2) Enzyme binding “allosteric effectors”
3) Covalent modification
4) Interaction with regulatory proteins
How does changes in levels of substrate affect activity?
- Activity increases when there is an increase in substrate
- At a certain point, the activity reaches a plateau
What are allosteric effectors?
Small molecules that interact with the enzyme and change its activity
Which amino acid residues can be modified by phosphorylation or dephosphorylation?
Serine
Threonine
Tyrosine
Give an example of how covalent modification can regulate the function of an enzyme.
The presence or absence of phosphate
How does interaction with regulatory proteins regulate enzymes?
Enzymes that function in multimeric complexes interact with many protein groups
Why are glycolysis and gluconeogenesis not favored at the same time? **
Pathways in opposite directions are NOT favoured simultaneously
What is the difference between glycolysis and gluconeogenesis?
Glycolysis: degrades glucose
Gluconeogenesis: synthesizes glucose
Why do cells regulate common pathways?
To maximize product utilization
