Lecture 36 Flashcards
Intro to Human Metabolic Design
bioenergetics
describes the transfer and utilization of energy (energy flow) in biological systems -> think about mitochondria
pg 944
free energy change (Gibbs free energy, ΔG)
a quantitative measure of the energy transfers between chemical reactions; can predict if the reaction will take place
pg 945
enthalpy change (ΔH)
a measure of the change in heat content of the reactants and products (heat released or absorbed during a reaction)
pg 945
entropy change (ΔS)
a measure of the change in randomness or disorder of reactants and products
pg 945
free energy change
- reactants must undergo a transition state with a higher energy level
- exergonic reactions: products have a lower energetic state -> ΔG is negative -> favorable reaction
- endergonic reactions: products have a higher energetic state -> ΔG is positive -> unfavorable reaction as they need added energy to take place
- The net ΔG = 0 when the reactant and product reach equilibrium
pg 946-948
ΔG and reactant concentration
- nonequilibrium reactions: [A]»[B], ΔG < 0, forward reaction will take place until equilibrium is reached
- standard conditions: [A]=[B], ΔG could be positive or negative
- equilibrium conditions: ΔG=0, concentrations likely not equal
- ΔG of a reaction is also dependent on the concentration of the reactants
pg 949
energy changes of metabolic pathways
watch lecture
- when the overall ΔG = ΔG1+ΔG2+ΔG3 is negative the pathway can proceed even if some ΔG of individual steps are positive
- the actual rate of the pathway depends on the activity of the enzymes that catalyze each step
pg 950
coupling of reactions
couple reactions with overall negative ΔG allow for the unfavorable reaction to proceed (ATP->ADP often coupled with unfavorable metbolic reactions to drive them forward)
pg 951-953
metabolism
a term used to describe the interconversion of chemical compounds in the body, the pathways taken by individual molecules, their interrelationships, and the mechanisms that regulate the flow of metabolites through the pathways
pg 955
overview of human metabolism
- energy-yielding nutrients -> catabolism -> energy-poor end products (catabolism releases chemical energy, ATP, NADH)
- precursor molecules -> anabolism -> complex molecules (takes energy extracted from catabolism to undergo anabolism)
- only separation of pathways is done by compartmentalization and substrate availability
pg 956
catabolism
- releases and captures energy in the form of ATP or reduced compounds (i.e. NADH, NADPH)
- allows nutrients to be converted into building blocks to be used for the synthesis of complex molecules of the body
- convergent pathway
- many precursors lead to a common intermediate
pg 957
catabolic pathways
- energy-yielding nutrients undergo digestion and absorption to be broken down into building blocks of macromolecules
- an activation step occurs (needed for molecules to enter a certain catabolic pathway) and then catabolism occurs
- catabolism leads to a common intermediate -> frequently acetyl-CoA which enters citric acid cycle
- citric acid cycle is the central metabolic pathway -> it is amphibolic (both catabolic and anabolic) and provides intermediates for anabolic pathways
pg 958
anabolism
- combines small molecules, such as amino acids, to make complex molecules, such as proteins
- requires energy which can be provided by: ATP or NADH or NADPH (provide electrons for chemical bonds)
- anabolism is a divergent process in which a few common biosynthetic precursors form a wide variety of complex products
pg 959
metabolic maps
help you see all the pathways and how they interact
pg 961
carbohydrate metabolism
- glycolysis (central pathway for all others)
- gluconeogenesis (GNG)
- glycogen metabolism
- fructose and galactose
pg 962
