Respiratory substrates and RQ calculations Flashcards
what is the relationship between the number of hydrogen atoms in respiratory substrate and the number of ATP generated
-during aerobic respiration most ATP is made during oxidative phosphorylation where hydrogen ions flow through channels in the inner mitochondrial membrane associated with ATP synthase enzymes, hydrogen ions and electorns then combine with oxygen to produce water =
so=
-more ATP can be produced
-more O2 is needed to respire the substrate
what is the RQ equation
Respiratory quotient = carbon dioxide produced/ oxygen consumed
work out the respiratory quotient for respiring carbohydrated
equation: C6H12O6 + 6O2 -> 6CO2O
CO2 produced= 6CO2
oxygen consumed= 6O2
6CO2/6O2
6/6 = 1
what is the main respiratory substrate for mammals
glucose, e.g brain, blood cells and muscles can only use glucose
animals convert glucose to glycogen for storage and can hydrolyse it back to glucose for respiration
other monosaccharides fructose and galactose are converted via isomerase enzyme into glucose for respiration
what is the energy yield from respiring carbohydrates
-glucose yiels 2870 KJ mol-1 (maximum theoretically)
-30.6 kj mol-1 is required to generate each ATP
= each mol of glucose can produce 93.8 mol ATP (2870/30.6)
-actual yield = around 30 mol ATP so only 32% efficient
-rest of energy is released as heat which helps maintain body temp allowing enzyme-controlled reactions to work at optimum
when are lipids used and how are they respired
-used when carbohydrate levels are low
-important respiratory substrate particularly in muscles
-oxidation (hydrolysis) of fats produces large amounts of hydrogen ions as each triglyceride is made of one glycerol and three fatty acid molecules
-glycerol is converted into triose phosphate and respired
-using ATP each fatty acid is combined with coenzyme A =transported to the matrix and broken down into two carbon acetyl groups each attached to CoA =this beta oxidation pathway generates reduced NAD and reduced FAD
what is the RQ from respiring lipids
equation: C18H36O2 + 26O2 -> 18CO2 + 18H20
RQ= 18CO2/ 26O2
18/26 = 0.7
what are the steps for balancing equations
-count carbons and balance
-count hydrogens and balance
-work out oxygens
explain processing of proteins
-excess amino acids released from digestion of proteins are deaminated in the liver
-deamination involves removal of the amino group and conversion to urea
-remaining part of the amino acid is a keto acid which enters the respiratory pathway as pyruvate, acetyl CoA or a krebs acid such as oxaloacetate
what is the energy yield from respiring proteins and when is it respired
RQ = 0.8-09 = less than one = more oxygen is used than CO2 given off
-only used during starvation fasting or prolonged exercise
-number of hydrogen atoms per mol in proteins is slightly greater than glucose so slightly more energy is released than per equivalent mass of carbohydrate
what does a RQ value greater than 1 may indicate
that some anaerobic respiration is taking place
what is the order f highest to lowest mean energy values
lipids= 39.4
protein =17
carbohydrates = 15.8
