week 3: bioenergetic pathways

Question 1

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

Answer 1

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

Question 2

what are the 4 systems that provide energy?

Answer 2

• instaneous
• immediate
• short term
• long term

Question 3

define/describe the process of the instantaneous system

Answer 3

• 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

Question 4

define/descibe the immediate energy system

Answer 4

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

Question 5

describe the first stage of the short term energy system

Answer 5

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

Question 6

2nd stage of short term energy system

Answer 6

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

Question 7

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

Answer 7

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

Question 8

describe aerobic glycolosis

Answer 8

• 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

Question 9

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

Answer 9

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)

Question 10

describe the ETC/oxiative phosphorlysation system

Answer 10

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