Intro to Metabolism Flashcards
What are metabolic pathways
series of enzyme catalyzed reactions
What are the intermediates of metabolic pathways
Metabolites or metabolic intermediates (substrates, pathway intermediates, products)
Where do pathways differ
Different organisms or tissues
What are the two main purposes of metabolism
make specific molecules to live and grow, obtain usable chemical energy from the environment
Slides
6, 14, 15, 19, 34, 42
What are nucleotides role in metabolism
Electron carriers
What are NAD and FAD
Nicotinamide adenine dinucleotide = co-substrate
Flavin adenine dinucleotide = prosthetic group
Both cofactors
Are NAD and NADP high energy?
No, NADH and NADPH are
What are phosphodiester bonds
C-O-P-O-C
What are phosphoanhydride bonds
C-O-P-O-P-O-C
What are NAD and NADP
Cosubstrates; loosely associated with enzyme
What are the dietary macromolecules that are the most significant fuel sources
Polysaccharides, triacylglycerols (fats)
How are excess fuels stored
Fatty acids as fat, CHO as glycogen in the liver and skeletal muscles
pH, [H2O], temp at biochemical standard state
7, 55M, 25 degrees
When will a reaction proceed in the forward direction
Delta G negative
What does delta G tell us
Whether the reaction proceeds, no information regarding rate of reaction. information regarding driving force to reach equilibrium (sense of direction and magnitude)
What happens if the delta G is - vs +
Negative = reaction proceeds spontaneously in the forward direction Positive = reaction will not proceed spontaneously in the forward direction
What is the difference between a reaction with a delta G around zero versus a very negative delta G
~ 0 = reversible
|»_space;>0 = irreversible (under cell conditions)
Characteristics of a reversible reaction
Delta G near zero, close to eq. Changes in concentration of AB may change direction
What is a high energy intermediate, what are the three types
Compounds containing “usable” chemical energy
- Electron carriers (NADH, NADPH, FADH2, FMNH2)
- Nucleoside triphosphate (NTPs: ATP, UTP, GTP)
- Thioesters
Is catabolism oxidative or reductive?
Oxidative; metabolites lose electrons, “oxidizing agents” (reduce cofactors), NAD, FAD, NADP
Is anabolism oxidative or reductive?
Reductive; metabolites gain electrons, “reducing agents,” NADH, FADH, NADPH
How much delta G from the hydrolysis and formation of phosphoanhydride bonds
Hydrolysis = -30 kJ/mol Formation = +30 kJ/mol
What is ATP, why is it high-energy, how is it formed
“energy currency”, high energy bc phosphoanhydride bond, generated by catabolism
What is ATP used in
movement, driving unfavourable reactions, primary active transport (ion pump)
What are thioesters
High E compounds, similar to esters but without electron delocalization
What is a coupled reaction
Energy released by an exergonic process can drive endergonic process. Only if linked by common intermediate
How can coupled reactions push and pull?
If one delta G is negative enough, it can compensate for a positive delta G
Are reversible steps regulated?
NO
What are “rate-limiting” steps
irreversible, regulated reactions
What are the two forms of inhibition/describe them
Product inhibition: enzyme inhibited by the product of its reaction
Feedback inhibition: enzyme inhibited by a metabolite further down the pathway
What is activation of an enzyme
“Feed-forward activation” ; enzyme may be activated by metabolite upstream
What is reciprocal regulation
Opposing pathways catalyze the “reverse reaction” of another pathway; regulated so both do not operate at the same rate
