BIOLOGY > MODULE 5 - RESPIRATION > Flashcards

MODULE 5 - RESPIRATION Flashcards

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1
Q

What is the need for cellular respiration?

A

the body needs energy and useable carbon compounds to work

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2
Q

what are the 4 types of ‘work’ that the body needs respiration to carry out? give examples for each

A
  • transporting substances across membranes e.g. active transport
  • anabolic reactions e.g. synthesis of DNA from nucleotides
  • movement e.g. mechanical contraction of muscles
  • maintaining body temp
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3
Q

describe the process through which the sun can be the primary source of energy for organisms

A
  • light energy is transformed into chemical potential energy in the synthesis of carbohydrates
  • the carbs formed are used in ATP synthesis (from their breakdown) or are combined and modified to form all useable organic molecules essential for plant metabolic processes
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4
Q

state the respiration equation

A

glucose + oxygen -> carbon dioxide + water + energy

C6H12O6+ 6O2 -> 6CO2 + 6H20 + 2870kJ

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5
Q

describe the mitochondrial outer membrane

A

smooth
permeable to several small molecules

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6
Q

describe the mitochondrial inner membrane

A

folded into cristae
less permeable
- is the site of the electron transport chain
- location of ATP synthase enzymes

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7
Q

describe the mitochondrial inter membrane space

A
  • low pH due to the high conc. of protons
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8
Q

describe the mitochondria matrix

A
  • an aqueous solution
  • contains ribosomes, enzymes, circular mitochondrial DNA
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9
Q

what type of mitochondria would be found in active cells like muscles?

A
  • larger mitochondria with longer more tightly packed cristae
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10
Q

what are the 4 stages in aerobic respiration?

A
  • glycolysis
  • link reaction
  • krebs cycle
  • oxidative phosphorylation
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11
Q

describe glycolysis in one sentence

A

phosphorylation and splitting of glucose

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12
Q

where does glycolysis happen?

A

cell cytoplasm

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13
Q

describe link reaction in one sentence

A

decarboxylation and dehydrogenation of pyruvate

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14
Q

describe the Krebs cycle in one sentence

A

a cyclical pathway with enzyme controlled reactions

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15
Q

describe oxidative phosphorylation in one sentence

A

production of ATP through oxidation of hydrogen atoms

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16
Q

where does link reaction take place?

A

the matrix of the mitochondria

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17
Q

where does the Krebs cycle take place?

A

matrix of the mitochondria

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18
Q

where does oxidative phosphorylation take place?

A

the inner membrane of the mitochondria

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19
Q

in glycolysis what happens ti the glucose molecule?

A
  • the glucose molecule is phosphorylated and therefore trapped in the cell
  • the glucose molecule is split in two
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20
Q

list the products of glycolysis

A
  • 2 Pyruvate molecules (3C)
  • net gain of 2 ATP
  • 2 molecules of reduced NAP
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21
Q

what are the steps in glycolysis?

A
  • phosphorylation
  • lysis
  • oxidation
  • phosphorylation
  • production of pyruvate
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22
Q

what happens in step 1 of glycolysis?

A

phosphorylation
- glucose (6C) is phosphorylated by 2 ATP to form hexose bisphosphate (6C)

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23
Q

what happens in step 2 of glycolysis?

A

lysis
hexose bisphosphate (6C) splits into 2 triose phosphate molecules (3C)

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24
Q

what happens in step 3 of glycolysis?

A

oxidation
- hydrogen is removed from each triose phosphate molecule and transferred to coenzyme NAD to from 2NADP

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25
what happens in step 4 of glycolysis?
phosphorylation - phosphates are transferred from the intermediate substrate molecule to form 4ATP through substrate linked phosphorylation
26
what happens in step 5 of glycolysis?
pyruvate is produced - pyruvate can be used in the next stage of respiration
27
what type of reaction in the link reaction?
oxidative decarboxylation reaction
28
why is the link reaction described as an 'oxidative decarboxylation reaction'?
because it simultaneously removes a carboxyl group as carbon dioxide (decarboxylation) and oxidizes the remaining 2-carbon fragment by removing hydrogen atoms (oxidation)
29
what is the first step in link reaction?
pyruvate is oxidised by enzymes to produce the 2C acetate and a co2 molecule - simultaneously, hydrogen ions are removed from the carbon that is lost through dehydrogenation - dehydrogenation is carried out by the coenzyme NAD - this forms reduced NAD (NADH)
30
what is the second step in link reaction?
acetate combines with coenzyme A to form acetyl coenzyme A
31
what are the products of link reaction?
- acetyl coenzyme A - co2 - reduced NAD
32
in link reaction, how does pyruvate enter the mitochondrial matrix? why?
it is actively transported because the inner mitochondrial membrane is impermeable to pyruvate, therefore specific carrier/transport proteins must actively transport it in - uses a small amount of ATP
33
what happens to a coenzyme in order for it to be reduced?
it must gain a hydrogen atom
34
what happens to a coenzyme in order for it to be oxidised?
it must loose a hydrogen atom
35
what is coenzyme A made of?
- a nucleoside (ribose + adenine) - a vitamin
36
which enzyme supplies the acetyl group from link reaction to the Krebs cycle?
coenzyme A
37
what is the ai of the Krebs cycle?
to collect high energy electrons from the reactions carried out during it
38
describe the Krebs cycle in one sentence
a series on enzyme controlled reactions
39
what is step 1 of the Krebs cycle?
acetyl coenzyme A enters the circular pathway from the link reaction in glucose metabolism
40
what happens in step 2 of the Krebs cycle?
oxaloacetate accepts the acetyl fragment from acetyl coenzyme A to form citrate
41
how many carbons in citrate?
6
42
how many carbons in oxaloacetate?
4
43
how many carbons in acetyl?
2
44
what happens in step 3 of the Krebs cycle?
citrate is converted back into oxaloacetate through a series of redox reactions
45
describe the regeneration of oxaloacetate
- citrate closes 2 carbons through decarboxylation: these are lost as waste co2 gas Then: 1: an NAD coenzyme is reduced through dehydrogenation (an oxidation reaction) to form NADH 2: another NAD coenzyme is reduced through dehydrogenation (an oxidation reaction) to form NADH 3: ADP is converted into ATP through substrate level phosphorylation 4: an FAD coenzyme is reduced through dehydrogenation (an oxidation reaction) to form FADH2 5: another NAD coenzyme is reduced through dehydrogenation (an oxidation reaction) to form NADH
46
how is NAD/FAD reduced into NADH/FADH2?
the carbon lost from the molecule through decarboxylation has hydrogen atoms on it - these hydrogen atoms are removed from the carbon and accepted by the coenzymes, reducing them
47
what is a hydrogen atom made of?
a hydrogen ion and an electron
48
what is the role of coenzymes NAD and FAD?
they play a role as electron carriers: - they transfer hydrogen atoms from different stages of respiration to the electron transport chain on the inner mitochondrial membrane
49
where are hydrogen atoms removed from coenzymes FADH2 and NADH?
on the electron transport chain on the inner mitochondrial membrane - this oxidises the coenzymes back into NAD/FAD
50
what happens to hydrogen atoms when they are released by coenzymes into the electron transport chain?
they are split into hydrogen ions and electrons: - the electrons are given to the electron transport chain - they hydrogen ions are released when the electrons are lost - the electron transport chain then drives the movement of the hydrogen ions across the inner mitochondria membrane, into the inter membrane space - this creates a proton gradient as more protons are in the inter membrane space
51
where does the energy for ATP synthesis come from?
the movement of hydrogen ions down the proton gradient and back into the mitochondrial matrix
52
where is NADH produced during aerobic respiration? how much is produced?
- 2 from glycolysis - 2 from link reaction - 6 from the Krebs cycle
53
where is FADH2 produced during aerobic respiration? how much is produced?
2 from the Krebs cycle
54
what are the products of oxidative phosphorylation?
many ATP molecules - water (produced from oxygen)
55
what does the chemiosmotic theory state?
that energy from electrons passed through the electron transport chain is used to pump protons up their concentration gradient, into the inter membrane space - the hydrogen ions are then allowed to flow by facilitated diffusion through a proton channel in ATP synthase, into the matrix - the energy of the hydrogen ions flowing down their concentration gradient is harnessed resulting in the phosphorylation of ADP into ATP by ATP synthase
56
what is the first step in oxidative phosphorylation?
- hydrogen atoms are donated by reduced NAD/FAD from the Krebs cycle
57
what is the second step in oxidative phosphorylation?
hydrogen stoms split into protons and electrons
58
what is the third step in oxidative phosphorylation?
the high energy electrons enter the electron transport chain and release energy as they move through it
59
what is the fourth step in oxidative phosphorylation?
the released energy is used to transport protons across the inner mitochondrial membrane from the matrix into the inter membrane space
60
what is the 5th step in oxidative phosphorylation?
a concentration gradient of protons is established between the inter membrane space and the matrix
61
what is the 6th step in oxidative phosphorylation?
the protons return to the matrix via facilitated diffusion through the channel protein ATP synthase
62
what is the 7th step in oxidative phosphorylation?
the movement of protons down their concentration gradient provides energy for ATP synthesis
63
what is the 8th step in oxidative phosphorylation?
oxygen acts as the 'final electron acceptor' and combines with protons and electrons at the end of the electron transport chain to form water
64
describe the structure of the electron transport chain
- it is made up of a series of membrane proteins/electron carriers which are positioned close together to allow the electrons to pass from carrier to carrier
65
why are electron carriers required to pump protons across the inner mitochondrial membrane?
the inner mitochondrial membrane is impermeable to protons - a concentration gradient must be established however
66
what two things occur couples together when hydrogen ions are transported through the proton channel in ATP synthase?
- ATP synthesis - the flow of protons
67
why is oxygen important in the electron transport chain?
- without oxygen the electron transport chain cannot continue as the electrons have no where to go - if oxygen doesn't accept the electrons and hydrogen ions the reduced coenzymes cannot be oxidised to regenerate NAD and FAD2, so they wouldn't be able to be used in further hydrogen atom transport
68
what characteristic of ATP makes it easy to move in and out of cells?
it is a small molecule
69
how is being water soluble useful to ATP?
energy requiring processes occur in aqueous environments
70
how is ATP able to be recharged with energy??
it is easily regenerated
71
does ATP release energy in large or small amounts?
small
72
in glycolysis and the Krebs cycle combined, how many ATP molecules are produced? how are they formed?
4 - substrate level phosphorylation
73
how many molecules of reduced hydrogen carriers are produced in the Krebs cycle?
12 - 10 NADH - 2 FADH
74
what happens to a hydrogen carrier when It is reduced?
it gains a hydrogen and two electrons
75
what two types of protein are found on the inner mitochondrial membrane?
- the electron transport chain - ATP synthase
76
which molecule transfers the electrons to the electron transport chain? how many at a time? (oxidative phosphorylation)
reduced NAD - 2 at a time
77
what happens to the proteins in the electron transport chain when they are given electrons? (oxidative phosphorylation)
they are reduced
78
what happens to the energy lost by electrons as they move down the electron transport chain? (oxidative phosphorylation)
it is used by the electron transport chain proteins to pump protons from the matrix into the inter membrane space
79
why to protons build up in the inter membrane space? (oxidative phosphorylation)
because the inner mitochondrial membrane is impermeable to protons
80
the 2 electrons loose all their energy as they travel down the electron transport chain. what happens next? state the equation. (oxidative phosphorylation)
- they combine with oxygen and 2 hydrogen ions to form water 2e- + 1/2 O2 + 2H+ =H2O
81
FADH also transfers electrons from the Krebs cycle to the electron transport chain. what is the difference between when FADH and NADH do it?
- NADH transfers electrons to the start of the chain - FADH transfers electrons to the middle of the chain
82
what is used by ATP synthase to generate ATP from ADP and Pi? what is this process called?
the movement of protons through the proton channel in ATP synthase - called chemiosmosis
83
in theory, how many molecules of ATP can oxidative phosphorylation provide per glucose molecule?
34
84
what 5 things occur when there is not enough oxygen for respiration?
- there is no final acceptor of electrons on the electron transport chain - the electron transport chain stops functioning - no more ATP is produced via oxidative phosphorylation - reduced NAD and FAD aren't oxidised by an electron carrier - no oxidised NAD/FAD is available for dehydrogenation in the Krebs cycle - the Krebs cycle stops
85
which stage of respiration continues in anaerobic respiration?
glycolysis
86
what are the two pathways of anaerobic respiration we learn?
- ethanol fermentation - lactate fermentation
87
which organisms use ethanol fermentation?
- Yeast + microorganisms
88
which organisms use lactate fermentation?
some microorganisms and mammal muscle cells
89
what happens (simply) in ethanol fermentation?
reduced NAD transfers its hydrogen to ethanal to form ethanol
90
which molecule is the hydrogen acceptor in ethanol fermentation?
ethanal
91
what are the two steps in ethanol fermentation?
- pyruvate is decarboxylated into ethanal + co2 is produced - ethanal is reduced to ethanol by alcohol dehydrogenase
92
can ethanol be further metabolised?
no - it is a waste product
93
what happens (simply) in lactate fermentation?
- reduced NAD transfers its hydrogens to pyruvate to form lactate
94
describe the first step in lactate fermentation
pyruvate is reduced to lactate by lactate hydrogenase
95
which molecule is the hydrogen acceptor in lactate fermentation?
pyruvate
96
can lactate be further metabolised?
yes
97
how many ways can lactate be further metabolised?
2
98
what are the 2 ways in which lactate can be metabolised?
- it can be oxidised back not pyruvate which is then channelled into the Krebs cycle for ATP production - it can be converted into glycogen for storage in the liver
99
what is an oxygen debt? why do animals get it?
the extra oxygen required by the body after intense exercise to break down lactic acid, which accumulates in muscles when oxygen supply cannot meet the high energy demand - the oxidation of lactate back into pyruvate needs extra oxygen
100
which type of respiration gives a higher yield?
aerobic
101
why does aerobic respiration have a higher energy yield than anaerobic respiration?
in anaerobic respiration glucose is only partly oxidised, meaning only some of its chemical potential energy is released and transferred to ATP - in anaerobic respiration the reactions in the mitochondria, which produce the most energy, cannot happen due to their being no final electron acceptor
102
what are the two stages of anaerobic respiration?
- glycolysis - fermentation
103
where does anaerobic respiration take place?
cytoplasm
104
what are the products of anaerobic respiration in yeast?
co2 and ethanol
105
what are the products of anaerobic respiration in mammals?
lactate
106
what happens when a cell's glucose supply for respiration has been used up?
the cell may continue using other substrates, such as other carbohydrates, lipids, and proteins
107
which alternative respiratory substrate is used last? why?
- the amino acids from proteins - they often have essential roles elsewhere, such as as ,along proteins which are used in the cytoskeleton and for enzymes
108
how much energy is released from alternative carbohydrates during respiration?
15.8KJg-1
109
how much energy is released from lipids during respiration?
39.4KJg-1
110
how much energy is released from proteins during respiration?
17KJg-1
111
why do different substrates have different energy values?
- different substrates have different amounts of hydrogen atoms
112
which factor determines the amount of energy a substrate has?
- molecular composition - specifically how many hydrogen atoms become available when the substrates molecule is broken down
113
why does the amount of hydrogen atoms in a substrate effect its energy value?
- a molecule with a higher hydrogen atoms content will result in a larger protons gradient across the mitochondrial inner membrane, which means more ATP is formed via chemiosmosis
114
which substrate molecule is made up of long hydrogen-carbon chains with many hydrogen atoms?
the fatty acids in lipids - all the hydrogen atoms are released when the lipid is broken down
115
what is a respirator quotient?
the ratio of co2 molecules produced to the oxygen molecules consumed (during respiration)
116
why do different respiratory substrates have different RQ values?
they have differing numbers of carbon-hydrogen bonds
117
why does a molecule with more hydrogen-carbon bonds need more oxygen to be broken down?
in order to break down the molecule, more oxygen is needed for the final stage of oxidative phosphorylation to form water
118
what is the RQ equation?
RQ = CO2 produced --------------------- O2 consumed
119
what is the RQ value of carbohydrates?
1RQ
120
why is the RQ value of carbohydrates 1?
equal amounts of co2 are produced to oxygen taken in when they are respired
121
what is the RQ value of lipids?
0.7RQ
122
what is the RQ value of proteins?
0.9RQ
123
why can an RQ value not be calculated for anaerobic respiration in muscle cells?
- no oxygen is used and no co2 is produced in lactate fermentation
124
why can an RQ value not be calculated for anaerobic respiration in yeast cells?
- no oxygen is used but co2 is still being produced - the RQ therefore tends towards infinity
125
what are the 3 steps in calculating the RQ value for a substrate undergoing aerobic respiration?
1) create respiration equation 2) balance the equation 3) use the RQ formula (co2 produced divided by o2 taken in)
126
which piece of equipment is used when measuring the rate of respiration?
respirometer
127
what is the apparatus needed for an investigation into the rate of respiration in Yeast?
- respirometer - test tubes - soda lime pellets - to absorb the co2 produced - glass beads - stopwatch - germinating seeds - will actively be respiring and consuming oxygen - temperature controlled water bath
128
list the 4 steps of an investigation into the rate of respiration in yeast
- measure o2 consumption - reset the apparatus - run the experiment again - repeat the experiment at different temps
129
describe step one of an investigation into the rate of respiration in yeast
- set up the respirometer and run the experiment with both tubes in a controlled temperature water bath - use the manometer reading to calculate the change in gas volume within a given time (xcm3min-1)
130
describe step two of an investigation into the rate of respiration in yeast
- allow air the reenter the tubes via the screw cap and reset the manometer fluid using the syringe - change the temperature of the water bath and allow the tubes to acclimate, then close the screen clip to begin the experiment
131
describe step 3 of an investigation into the rate of respiration in yeast
- use the manometer reading to calculate the change in gas volume in a given time (ycm3min-1)
132
in a respirometer experiment, how would you calculate the volume of oxygen consumed?
- can be worked out using the radius of the capillary tube (r) - measured in cm - and the distance moved by the manometer fluid (h) - measured in cm in a minute - must use the equation π r2h
133
in a respirometery experiment what can the rate of oxygen consumption be taken as
the rate of respiration for organisms
134
what is the rate of oxygen consumption measured in (respirometer)
(cm3min-1)
135
what is one limitation of a respirometery experiment?
cannot be used to measure respiration as no oxygen is consumed during it
136
what are the glass beads in a respirometer used for?
a control
137
how does a respirometer work?
- the seeds in the experimental tube are respiring and using up oxygen - this causes the manometer fluid to move through the tube (coloured red) - the amount of manometer fluid used up is measured against a ruler - any co2 produced is absorbed by the soda lime pellets
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