Respiration Flashcards
1
Q
why do we need to respire?
A
we need energy for biological processes
2
Q
Why do plants need energy?
A
active transport (uptake of minerals from roots) DNA replication photosynthesis protein synthesis cell division
3
Q
Why do animals need energy?
A
maintaining body temperature muscle contraction active transport DNA replication cell division protein synthesis
4
Q
Outline glycolysis
A
- splitting of one molecule of glucose (6C) into 2 smaller molecules of pyruvates (3C)
- occurs in cytoplasm
- first stage in aerobic and anaerobic respiration
- itself is anaerobic process as requires no 02
5
Q
Explain glycolysis
A
- 2 stages: phosphorylation and oxidation
- in phosphorylation, 1 molecule of glucose (6C) is phosphorylated by adding 2 phosphate groups from 2 ATP molecules forming one molecule of hexose bisphosphate (6C) and 2 molecules of ADP.
- Hexose bisphosphate is unstable and splits further into 2 smaller molecules of triose phosphate (3C)
- In oxidation, the 2 triose phosphates each lose a hydrogen ion which is collected by NAD forming reduced NAD.
- 2 ATP molecules are formed from each triose phosphate from being directly converted into a pyruvate.
6
Q
What are the products of glycolysis?
A
- 2 reduced NAD - go to oxidative phosphorylation
- 4 ATP - used for energy
- 2 pyruvates - actively transported to matrix for link reaction
7
Q
How much ATP is produced in glycolysis?
A
4 ATP but net gain of 2 as 2 were used up in phosphorylation
8
Q
Outline link reaction
A
- occurs in matrix
- requires 02
- conversion of pyruvate into acetate
9
Q
Explain link reaction
A
- pyruvate (3C) is decarboxylated as 1 Carbon is removed in the form of CO2
- NAD collects H+ion from the pyruvate forming a reduced NAD molecule and acetate (2C)
- Acetate combines with coenzyme A forming acetyl coenzyme A
10
Q
What are the total products of link reaction and why?
A
- 2 pyruvates produced form glycolysis so link reaction occurs twice for each glucose molecule
- 2 acetyl coenzyme A - go to krebs cycle
- 2 reduced NAD - oxidative phosphorylation
- 2 C02 - released as waste
11
Q
Outline Krebs cycle
A
- occurs in matrix
- occurs twice for each glucose molecule as 2 pyruvates so 2 acetates
12
Q
Explain krebs cycle
A
Co-enzyme drops acetate off at the krebs cycle and go back to link reaction to be reused
- acetate (2C) combines with oxaloacetate (4C) forming citrate (6C)
- citrate undergoes decarboxylation and dehydrogenation as it loses 1 C in form of CO2 and 1 H atom which is collected by NAD forming 1 reduced NAD and a 5 carbon compound.
- 5carbon compound undergoes decarboxylation as it loses 1 C in form of CO2 and dehydrogenation as 2 NAD and 1 FAD collect 3 H atoms forming 2 reduced NAD and 1 reduced FAD. ATP is also formed by substrate level phosphorylation which is where a phosphate groups is being directly transferred from one intermediate compound to ADP
- oxaloacetate is now formed
13
Q
What are the products of krebs cycle per cycle?
A
- 1 ATP - for energy
- 3 reduced NAD - oxidative phosphorylation
- 1 reduced FAD - oxidative phosphorylation
- 2 CO2 - waste
- coenzyme A - regenerated for next use in link reaction
- 1 oxaloacetate - regenerated for next use in krebs cycle
14
Q
outline electron transport chain
A
- process where energy carried by electrons from coenzymes is used to make ATP
- occurs in inner mitochondrial membrane
15
Q
Explain electron transport chain
A
- reduced FAD and NAD are oxidised making FAD and NAD so H atoms are released which are split into electrons and protons (H+ ions)
- 3 electron carriers make up electron transport chain which is located in inner mitochondrial membrane which folds into cristae so an increased SA maximises respiration
- electrons move along the electron transport chain losing energy at each carrier
- carriers use the energy to pump protons across the membrane into inter membrane space from matrix
- proton concentration is higher in inter membrane space so electrochemical gradient formed
- protons move down electrochemical gradient via ATP synthase into matrix
- movement of protons back into the matrix drives synthesis of ATP from ADP and P (I)
- at end of chain, protons, electrons and 02 combine to form water
- 02 is final electron acceptor
