week 3: bioenergetic pathways Flashcards
what are the two fundemental metabolic energy systems used to provide energy?
anerobic:
- substrate level phosphorlisaton, does not require oxygen
- have a higher rate of production of ATP, but lower capacity
aerobic:
- ‘oxidative phosphorylation’
- equires oxygen
- has more steps involved but has a hgiher capacity
what are the 4 systems that provide energy?
- instaneous
- immediate
- short term
- long term
define/describe the process of the instantaneous system
- some free intermuscular ATP (from hydrolosis) is avialable within the muscle
- this store is extremeley limited
- can supply energy to supply intense contractions for around 2 secs
define/descibe the immediate energy system
known as the ATP-PC/ phosphagen system
- has short duration but rapid energy production
- lasts 1-10 secs
- is anerobic metabolic system
- phosphocreatine (PCr) + ADP = Creatine + ATP
- enzyme is creatin kinase (CK)
- cleavage of the PCr = energy release
- despite high energy yeild is not currency for engy like ATP
describe the first stage of the short term energy system
- glycolosis
- in order for glycolosis to occur, glucose needs to be phosphorolated to stay inside the cell and not diffuse out. this is done by:
- glucose —–> (glucokinase/hexonase + ATP) = phospohated glucose
- phosphorolated glucose = 2 ATP, 2 NADH, 2 pyruvate
- lasts 1-2 minutes
- yeild = 2 ATP : 1 glucose
- needs constant supply of NAD to continue therfore needs anerobic glycolosis to occur
2nd stage of short term energy system
anerobic glycolosis:
- pyruvate —–> (lactic dehydrogenose) = lactic acid + NAD
- most pyruvate is converted to lactic acid to continue the glycolosis cycle
what are the 3 systems used in the long term engy system?
- aerobic glycolosis
- citric acid cycle (Krebs)
- electron transport chain
describe aerobic glycolosis
- happens in the presence of oxygen
- the pyruvate made from glycolosis, diffuses into mitochondria
- pyruvate——> (coenzyme A) = acetyl COa + 2CO2+4H
- there is no ATP yeild but the products made contribute to the next 2 cycles
- descirbe the Krebs cycle
- what is the result from both glycolosis and the krebs cycle?
it is cyclic in nature because:
- acetyl CoA enters cycle to produce conenzyme A, which is combined with pyruvate to produce more acetyl CoA (aerobic glycolosis)
chemical equation:
- 2 Acetyl CoA + 6 H2o + 2 ADP= 4CO2+ 16H+2Coa+ 2ATP
end result?
- low energy yeild, however releases important molecules for ETC
- throughout the cycle NAD+ is converted to NADH which is high energy stoing molecule
- produces 4 NADH, 1 FADH per pyruvate (krebs has x2 pyruvate)
at end of glycolosis + Krebs
- 1 glucose = 10 NADH (2x glycolosis, 8x krebs), 2 FADH (krebs)
describe the ETC/oxiative phosphorlysation system
- NADH from krebs is oxidised to produce NAD+, H+, -2e (also ionised becuase electrons were removed)
- freed electrons enter ETC and reach cytochome oxidase
- during ATC Energy is released specifically for ATP replenishment
- this energy pumps H+ ions out of ETC into intermembrane space (between membranes of mitochondria)
- chemical and voltage gradient is created by increase of H+, this drives ATPsynthase activity to put H+ back into inner membrane
- energy from the flow of H+ is used to convert ADP to ATP
- ATP moves to cytoplasm and produces work
- this system prouces CO2 as a byproduct
- also prouces H2o
- yeild is high. 30 - 32 ATP: 1 glucose after glycolosis, CAC, ETC
- this system also uses toher substrates such as fats