week 3: bioenergetic pathways Flashcards

1
Q

what are the two fundemental metabolic energy systems used to provide energy?

A

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

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2
Q

what are the 4 systems that provide energy?

A
  • instaneous
  • immediate
  • short term
  • long term
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3
Q

define/describe the process of the instantaneous system

A
  • 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
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4
Q

define/descibe the immediate energy system

A

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

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5
Q

describe the first stage of the short term energy system

A
  1. 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
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6
Q

2nd stage of short term energy system

A

anerobic glycolosis:
- pyruvate —–> (lactic dehydrogenose) = lactic acid + NAD
- most pyruvate is converted to lactic acid to continue the glycolosis cycle

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7
Q

what are the 3 systems used in the long term engy system?

A
  • aerobic glycolosis
  • citric acid cycle (Krebs)
  • electron transport chain
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8
Q

describe aerobic glycolosis

A
  • 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
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9
Q
  • descirbe the Krebs cycle
  • what is the result from both glycolosis and the krebs cycle?
A

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)

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10
Q

describe the ETC/oxiative phosphorlysation system

A
  1. NADH from krebs is oxidised to produce NAD+, H+, -2e (also ionised becuase electrons were removed)
  2. freed electrons enter ETC and reach cytochome oxidase
  3. during ATC Energy is released specifically for ATP replenishment
  4. this energy pumps H+ ions out of ETC into intermembrane space (between membranes of mitochondria)
  5. chemical and voltage gradient is created by increase of H+, this drives ATPsynthase activity to put H+ back into inner membrane
  6. energy from the flow of H+ is used to convert ADP to ATP
  7. 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
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