Energy Reactions in Cells Flashcards
(134 cards)
1
Q
Define metabolism
A
The set of processes which derive energy and raw materials from food stuffs, and use them to support repair, growth and activity of the tissues of the body to sustain life.
2
Q
Where does food go after it’s eaten?
A
GI tract
3
Q
What is the overall purpose of food?
A
To supply the energy needs of the cell
4
Q
What is food broken down into?
A
Nutrients
5
Q
What happens once food has been broken down into nutrients in the GI tract?
A
They pass into the blood
6
Q
What happens to food not absorbed into blood?
A
It is lost as faeces
7
Q
What happens to the nutrients in the blood?
A
They are taken up by the tissues
8
Q
What happens to nutrients in the tissue?
A
- Interconversion
- Storage (packaging nutrients into stores)
- Synthesis
- Utilisation
9
Q
What happens to utilised nutrients in the tissues?
A
They can pass back into blood for transport
10
Q
How can nutrients be used for energy?
A
They can be oxidised
11
Q
What happens to any waste produced from the oxidation of nutrients?
A
It’s passed back into the blood, and then lost from the kidneys or lungs
12
Q
How does biological chemistry occur?
A
In small, controlled, step-wise chemical changes
13
Q
What are metabolic reactions organised into?
A
Metabolic pathways
14
Q
Describe the nature of the metabolic pathways
A
Distinct but integrated
15
Q
What allows for the interconnectivity of metabolism?
A
Staging points on pathways where nutrients can enter or leave
16
Q
Do the metabolic pathways occur in all cells?
A
Some do, but some restricted to certain cell types, or compartments of cells
17
Q
Give an example of a pathway that occurs in all cells
A
Glycolysis
18
Q
What is which metabolic pathways occur in which cells related to?
A
Function
19
Q
What do all pathways have?
A
- Start point
- End point
- Interconnections
- Intermediates
20
Q
What are the intermediates in metabolic pathways known as?
A
Metabolites
21
Q
What are the two main types of metabolic pathway?
A
NAME?
22
Q
What do catabolic pathways do?
A
Break down larger molecules into smaller ones
23
Q
What are smaller molecules produced in catabolic processes known as?
A
Intermediary metabolites
24
Q
What do catabolic processes release?
A
Large amounts of free energy
25
How do catabolic processes release free energy?
Breaking chemical bonds
26
Are catabolic processes oxidative or reductive?
#NAME?
27
What is meant by catabolic processes being oxidative?
They release H atoms- ‘reducing power’
28
What are the H atoms released by oxidative processes used for?
Can be used to fuel production of energy currency, or fuel biosynthesis in another pathway
29
What is the result of the metabolic steps being small?
Release small amounts of energy per step
30
What is the advantage of releasing small amounts of energy per step?
It can be captured for the future
31
What do we need catabolism for?
To allow synthesis within cells
32
What do anabolic processes do?
Synthesise larger cellular components from intermediary metabolites
33
What do anabolic processes need?
Energy in the form of ATP released from catabolism
34
Are anabolic processes oxidative or reductive?
#NAME?
35
What is meant by anabolic processes being reductive?
They use H's
36
Give the 4 products of catabolic metabolism
- Building block materials
- Organic precursors
- Biosynthetic reducing power
- Energy for cell function
37
Give 3 examples of building block materials
#NAME?
38
What is meant by there being a dynamic state of cellular components?
There is interconversion between each other to meet cells needs
39
What are building block materials needed for?
- Cell growth
- Division
- Repair
40
Give an example of an organic precursor
Acetyl CoA
41
What is Acetyl CoA required for?
Interconversion of building block materials
42
Give two examples of molecules that capture biosynthetic reducing power
#NAME?
43
What do molecules that capture biosynthetic reducing power do?
Capture H atoms
44
What is the energy content of fat?
37kJ/g
45
What is the energy content of carbohydrate?
17kJ/g
46
What is the energy content of protein?
16kJ/g
47
What is the energy content of alcohol?
29kJ/g
48
What is the basal metabolic rate for a 70kg man/ 58kg woman?
1700/1400kcal
49
What is meant by basal metabolic rate?
The energy required by an awake individual during physical, emotional and digestive rest at 18ºc by all the body tissues
50
How much energy is required for activity?
1000-3000kcal
51
How much energy is required for the specific dynamic action of food?
150kcal
52
What is the specific dynamic action of food?
The energy cost of ingestion, digestion and absorption of food- extracting molecules in a form that we can get into body
53
How long can we survive without food?
20-70 days, if given water
54
What do food regulatory mechanisms do?
Govern supply, storage and utilisation of energy
55
What can happen to the different forms of energy?
They’re all interconvertible
56
What type of energy does biology predominantly use?
Chemical bond energy
57
How is chemical bond energy used?
#NAME?
58
What is meant by man being isothermal?
They cannot use heat energy for work
59
What are all cellular activities expressions of?
Chemical reactions in which chemical bonds are broken or formed
60
What is meant by exergonic?
Releases energy
61
Are exergonic reactions catabolic or anabolic?
#NAME?
62
What is the sign for ∆G in exergonic reactions?
Negative
63
Are exergonic reactions spontaneous?
Yes
64
What is meant by endergonic?
Requires energy
65
What is the sign for ∆G in endergonic reactions?
Positive
66
Are endergonic reactions spontaneous?
No
67
What do endergonic reactions require?
Energy input
68
What is the intermediate energy position?
The high energy as a result of activation energy, caused by the necessity to bring things together
69
What are the conditions for standard free energy change (∆Gº)?
25ºc, 101kPa, 1 molar concentrations of reactants and products
70
What additional condition exists for ∆Gº ’ ?
At pH 7.0
71
What is ∆G equal too in non-standard conditions?
∆Gº + RT . log n ([products]/[reactants])
72
Where may non-standard conditions be found?
In a cell
73
What determines free energy?
The ratio of products to reactants in the body
74
What does the ∆G sign indicate?
If the reaction is spontaneous or not
75
Why does the ∆G sign not indicate rate?
It may be that a reaction has a very high activation energy, or a very low rate.
76
How is the chemical bond energy of fuel molecules released?
Oxidation reactions
77
What is oxidation?
Removal of e - or removal of H + atoms
78
What are all oxidation reactions accompanied by?
Reduction
79
Why do oxidation reactions have to be accompanied by reduction reactions?
H atoms must be passed on
80
What happens when fuel molecules are oxidised?
e - and H + are transferred on to carrier molecules
81
Why does the cell have a choice of how to use reduced power?
Because it’s not in a linear pathway
82
Give the 3 major H carrier molecules in their oxidised forms
- NAD +
- NADP +
- FAD
83
Give the 3 main H carrier molecules in their reduced forms
- NADH + H +
- NADPH + H +
- FADH 2
84
Why is NAD(P)H and H + formed?
One H + quickly dissociates
85
How does the total concentration of oxidised and reduced carriers vary?
It doesn’t- it remains constant
86
Why does the total concentration of oxidised and reduced carriers remain constant?
The carriers are converted back and forth so they can pick up more energy in a cycle
87
What does NADH + H + act as the reducing power for?
ATP production
88
What does NADPH act as the reducing power for?
Biosynthesis
89
What do H carrier molecules contain?
Certain components from B vitamins
90
How are oxidised H carriers converted to their reduced form?
Adding 2 H atoms
91
What happens to H + in solution with H carriers?
It dissociates, leaving one electron behind on the carrier
92
What does NAD(P) + contain?
#NAME?
93
Why is the nicotinamide group with conjugated ring important?
Because the ring can pick up electrons to redistribute them
94
What is the result of the conjugated ring’s ability to redistribute electrons?
It allows the H atom to bind
95
How does FAD + differ from the other two carrier molecules?
It is similar, but has different electron capturing structure
96
What kind of process is the release of energy from food?
Exergonic
97
How has the oxidation of food captured bond energy?
Onto reducing equivalents
98
How can reducing equivalents drive energy requiring activities?
By coupling systems
99
What is meant by coupling systems?
Coupling carriers to other processes
100
Give an example of when coupling systems can be used directly
The use of NADPH drives biosynthesis
101
Give an example of where coupling systems can be used indirectly?
In the mitochondria electron transport system
102
What happens in the mitochondrial electron transport system?
NADH is coupled to production of ATP- electrons are fed into system, energy stripped out to drive ATP production
103
What bond in ATP is hydrolysed?
The bond between the terminal phosphate and the rest of the molecule
104
What happens when the terminal phosphate bond is hydrolysed?
It releases a phosphate and energy
105
What can be used to drive ATP synthesis?
Energy released in an exergonic reaction
106
How is part of the free energy released in a exergonic reaction conserved?
As chemical bond energy in the terminal phosphate of ATP
107
How much supply of ATP does a cell have?
A few seconds
108
What is the consequence of only having a few seconds supply of ATP?
It must cycle
109
Is ATP stable?
Yes, in the absence of a specific catalyst
110
What is the result of ATP being stable?
In controls the energy flow to prevent wasteage
111
When does catabolism slow?
When there is nowhere for the energy to go
112
What happens to catabolism when the energy has been used?
It restarts
113
What happens when [ATP] is high?
Anabolic pathways are activated
114
Why are anabolic pathways activated when [ATP] is high?
It is a high energy signal, so they know they have enough energy for biosynthesis
115
What happens when [ATP] is low, and [AMP] and [ADP] is high?
Catabolic pathways are activated
116
What is the effect of adenylate kinase (myokinase)?
2 ADP are converted to AMP and ATP
117
Give 4 high energy signals
- ATP
- NADH
- NADPH
- FADH 2
118
Give 5 low energy signals
- ADP
- AMP
- NAD +
- FAD +
- NADP +
119
What happens when supply > demand?
Energy most often stored in form of polymer macromolecules of fuel molecules
120
Give an example of a cell type that may need to increase metabolic activity very quickly?
Skeletal muscle
121
What is required for cell types that may need to increase their metabolic rate very quickly?
A high energy store reserve for emergencies
122
What is the high energy store reserve for emergencies?
Creatine phosphate
123
When is creatine phosphate produced in cells?
When ATP levels are high
124
Give the equation for the formation of creatine phosphate
Creatine + ATP -> Creatine Phosphate + ADP
125
What enzyme is required for the production of creatine phosphate?
Creatine kinase
126
What happens if [ATP] suddenly drops?
The creatine phosphate reaction reverses, producing a short term boost of [ATP]
127
How can creatine kinase (CK) be used clinically?
As a myocardial infarction (MI) marker
128
Why can CK be used as a MI marker?
CK is made up of 2 sub units. Different isoform combinations are found in different tissues, as there are 2 different proteaceous sub units of 2 genes that could form CK. One of the isoform combinations is CK-MM at 70% and CK-MB at 25-30%, which is specific to heart muscle. Normally CK is not in the muscle, so if it is present in a blood test in that isoform combination, it shows you there has been heart muscle damage, as CK is released from myocytes when damaged in MI.
129
Other than MI, what can CK be used as a clinical marker for?
Muscle infarction
130
What isoform is found in blood if there has been a muscle infarction?
98% MM and 1% MB
131
What happens to creatine and phosphocreatine spontaneously?
They break down slowly, at a steady rate, to creatinine
132
When is the breakdown of creatine and phosphocreatine not slow and steady?
In the case of muscle wasteage
133
How is creatinine excreted?
Via the kidneys
134
How can creatinine measurements be used clinically?
- Excretion per 24 hours is proportional to muscle mass
- Concentration in urine can be a marker of urine dilution
- Can be used to standardise other tests
