Respiration Flashcards
1
Q
Metabolism
A
All chemical reactions that take place in a cell
2
Q
Glycolysis
A
Splitting of 6-carbon glucose into two 3-carbon pyruvate
3
Q
Describe the process of glycolysis
A
- substrate level phosphorylation of glucose using 2 ATP to raise to higher energy
- phosphorylated glucose splits into two triose phosphate
- triose phosphate is oxidised by removing hydrogen to produce NADH
- releases some energy to phosphorylate ADP to ATP
4
Q
State where glycolysis occurs
A
cytoplasm
5
Q
State the products of glycolysis per glycose
A
- 4 ATP (net ATP 2)
- 2 NADH
6
Q
Suggest how red blood cells (which have no mitochondria) produce ATP
A
- anaerobic respiration
- glycolysis in cytoplasm produces ATP
7
Q
Link Reaction
A
Production of 2-carbon acetyl coenzyme A from 3-carbon pyruvate
8
Q
Describe the process of link reaction
A
- decarboxylation of pyruvate by losing CO2
- 2-carbon compound loses hydrogen by oxidation
- reduced NAD and 2-carbon acetate formed
- acetate combines with coA to form acetyl coA
9
Q
Suggest how pyruvate enters the mitochondria
A
active transport
10
Q
State where link reaction and Kreb’s cycle occur
A
mitochondrial matrix
11
Q
Kreb’s Cycle
A
- acetyl coA combines with 4-carbon oxaloacetate from previous cycle
- forms 6-carbon citrate
- decarboxylation and oxidation of citrate forms NADH and 5-carbon sugar
- decarboxylation and oxidation of 5-carbon sugar forms 2 NADH and FADH2
- oxaloacetate reformed
- some energy released for substrate level phosphorylation of ADP to ATP
12
Q
State products of Kreb’s cycle per glucose
A
Kreb’s cycle occurs twice
- 2 ATP
- 4 CO2
- 6 NADH
- 2 FADH2
13
Q
Suggest reasons Kreb’s cycle is significant
A
- source of intermediate compounds required to manufacture fatty acids, amino acids etc.
- provides hydrogen atoms carried by coenzymes NAD and FAD for oxidative phosphorylation = ATP
- regenerates 4-carbon oxaloacetate
14
Q
Suggest how hydrogen atoms carried by coenzymes NAD and FAD are used to release energy
A
- electrons travel along e- transport chain and H+ pumped across to intermembramal space
- provides energy for oxidative phosphorylation
- produces ATP
15
Q
State where oxidative phosphorylation occurs
A
cristae
16
Q
Describe the process of oxidative phosphorylation
A
- NADH and FADH2 donate electrons from hydrogen atom they are carrying to first electrons carrier (NADH dehydrogenase)
- electrons passed along electron transport chain
- in series of oxidation-reduction reactions
- energy released causes H+ to be pumped into intermembranal space
- chemiosmosis of H+ down electrochemical gradient through ATP synthase
- enzyme changes shape releasing energy to phosphorylate ADP to ATP
17
Q
Explain importance of oxygen in oxidative phosphorylation
A
- final acceptor of H+ and electrons
- prevents back up along chain stopping respiration
- produces safe product of water
18
Q
Explain why mitochondria have many folds in their inner membrane (cristae)
A
- large surface area
- for attachment of carrier proteins
- oxidative phosphorylation
19
Q
Explain what is meant by electron transfer chain
A
- e- passed along a series of e- carrier proteins
- each has a slightly lower energy level than previous
(down energy gradient) - in oxidation-reduction reactions
20
Q
Suggest how energy is transported efficiently in the electron transport chain
A
- energy released gradually
- in small amounts
- less wastage/used usefully
21
Q
Explain how lipids are used in respiration
A
- lipids hydrolysed to fatty acids and glycerol
- glycerol is phosphorylated to triose phosphate
- triose phosphate => pyruvate => acetyl coA enters Kreb’s
- fatty acids => acetyl coA for Kreb’s cycle
22
Q
Suggest why lipids release more energy compared to carbohydrates
A
- fatty acids contain greater proportion of carbon atoms
- able to produce many acetyl coA
- which produces ATP from Krebs cycle plus NADH/FADH
- NADH/ FADH donates H to electron transport chain to produce more ATP
- so lipids require more oxidation
23
Q
Explain how proteins and used in respiration
A
- proteins are hydrolysed to amino acids
- amino acids are deaminated
- remaining C used to make pyruvate and carbon intermediates for Kreb’s cycle
24
Q
Give reasons why aerobic respiration is inefficient
A
- proton leakage through proton pumps so do not all form ATP
- energy lost as heat
- active transport of pyruvate/NADH requires ATP
25
Describe anaerobic respiration in animals
- all NAD and FAD is reduced
- Kreb's cycle and e- transfer chain stop
- NADH gives up hydrogen to pyruvate forming lactate
- oxidised NAD allows further glycolysis = more ATP
26
Describe anaerobic respiration in plants
- all NAD and FAD is reduced
- Kreb's cycle and e- transfer chain stop
- pyruvate decarboxylated
- NADH gives up hydrogen to 2-carbon compound forming ethanol
- oxidised NAD allows further glycolysis = more ATP
27
Suggest how anaerobic respiration provides a survival advantage for animals
- allows ATP production to continue in oxygen shortage
- muscles can continue to work for a short time
- lactate can be oxidised back to pyruvate
- further oxidised to release energy
28
Suggest drawbacks of anaerobic respiration in animals
- produces lactic acid
- lactic acid causes cramps and muscle fatigue
- pH decreases so affects enzyme activity
29
Suggest two ways ATP is produced in respiration
- substrate level phosphorylation
| - oxidative phosphorylation
30
Suggest how the majority of ATP is produced
- oxidative phosphorylation
31
Suggest what would happen if carbon dioxide remained in mitochondria
- lower pH
| - denature enzymes involve in respiration
32
Suggest why it is essential that oxidised NAD is regenerated in anaerobic respiration
- needs to oxidise more triose phosphate
| - allows glycolysis/ fermentation to occur
33
Gives uses of ATP in a cell
- active transport
- cell division
- synthesis of DNA, proteins etc.
- muscle contraction
- nerve impulses
- phosphorylation
34
Suggest why link reaction and Kreb's cycle cannot occur in absence of oxygen
- without oxygen oxidative phosphorylation cannot occur
- NAD cannot be produced
- glycolysis produces lactic acid instead of pyruvate
- pyruvate is required for link reaction hence Kreb's
35
Suggest why less ATP is produced in anaerobic respiration
Glucose is not completely broken down
36
Suggest why glucose is the preferred respiratory substrate
- glucose readily available to cells since concentration in blood remains relatively constant
- fats and proteins required for other uses (i.e. fats for insulation and proteins for growth, repair etc.)
- proteins produce toxic urea from deamination
37
Suggest why respiration of lipids required more oxygen compared to carbohydrates
- greater proportion of carbon atoms from fatty acid chain
- many acetyl coA enter Krebs cycle to produce NADH/FADH
- NADH/FADH donate hydrogen to electron transport chain
- oxygen is final acceptor of hydrogen
- lots of oxygen required to prevent backing up chain and stopping respiration
38
Oxidative Phosphorylation
- process in which ATP is formed
- as a result of the transfer of electrons from NADH or FADH 2
- to O 2 by a series of electron carriers
