BM109 > Block B > Flashcards

Block B Flashcards

(48 cards)

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1
Q

What is the first law of thermodynamics

A

Energy can neither be created nor destroyed (law of conservation of energy)

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2
Q

What is the second law of thermodynamics

A

The universe tends towards disorder (law of entropy)

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3
Q

What is entropy and what are the energy levels with high entropy vs low entropy

A

The degree of randomness in any system
High entropy = low energy level
Low entropy = high energy level

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4
Q

What increases the entropy and why

A

Heat because it increases the random motion of molecules

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5
Q

What is kinetic energy

A

Movement

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6
Q

What is potential energy

A

Stored energy

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7
Q

What is the enthalpy of a molecule

A

The total energy contained within the molecule / total heat content

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8
Q

What changes a molecules enthalpy

A

The conversion to a different structure during a chemical reaction, symbolised as ΔH

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9
Q

What is anabolism

A

Building molecules and consuming energy

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10
Q

What is catabolism

A

Breaking down molecules and releasing energy

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11
Q

What is hydrolysis

A

A chemical reaction where a water molecule is used to break a bond in a compound

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12
Q

What is phosphorylation

A

The attachment of a phosphate to a molecule

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13
Q

What is hydrogenation

A

A chemical reaction where hydrogen H4 is added to a compound

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14
Q

What are the 5 stages in an enzyme catalysed reaction

A

1 - substrates enter the active site
2 - substrates are held in the active site by weak interactions
3 - substrates are converted to products
4 - products are released
5 - active site is available for new substrates

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15
Q

What are the 2 mechanisms of enzymes

A

Lock and key - the shape of the active site is specific to the substrate and is a fixed shape
Induced fit - shape of the active site is flexible and changes shape to fit the substrate more snugly after binding

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16
Q

What type of bond is there between nucleotides

A

Covalent bonds

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17
Q

Examples of energy intermediates

A

ATP and NADH

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18
Q

What is entropy

A

The degree of disorder of a system

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19
Q

When a physical system becomes more disordered, the entropy _____

A

Increases

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20
Q

What is the role of cofactors

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A

Stabilising the enzyme or substrate
Facilitating the reaction by acting as electron carriers or by transferring groups like hydrogen, phosphate or acetyl

21
Q

What are inorganic cofactors

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A

Metal ions, eg. Magnesium, iron, zinc
Can be permanently bound to the enzyme or can assist the reaction temporarily

22
Q

What are organic cofactors

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A

Coenzymes - bind loosely and temporarily to the enzyme
Prosthetic groups - bind covalently and permanently

23
Q

The classification of enzymes by the reaction catalysed
Oxidoreductases

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A

Oxidation and reduction reactions eg dehydrogenases

24
Q

The classification of enzymes by the reaction catalysed
Transferases

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A

Transfer a chemical group from one substrate to another eg kinases

25
The classification of enzymes by the reaction catalysed Hydrolases
Hydrolysis (water splits the bond) of C-O, C-N, O-P, C-S bonds eg esterases, proteases, phosphatases
26
The classification of enzymes by the reaction catalysed Lysases
Addition across a carbon-carbon double bond eg dehydratases, hydratases, decarboxylases
27
The classification of enzymes by the reaction catalysed Isomerases
Intramolecular rearrangements
28
The classification of enzymes by the reaction catalysed Synthetases
Formation of bonds between 2 substrates
29
The 6 factors affecting enzyme activity
pH Temperature Concentration of enzyme Concentration of substrate Inhibitors and activators Covalent modification of enzyme
30
What is the specific activity of an enzyme and what does it give a measurement of
The activity of an enzyme per mg of total protein (expressed in μmol min-1mg-1) Measures the purity of the enzyme
31
What are the 3 most important parts of metabolism
Energy - sometimes released, sometimes required Carbon skeletons - building blocks Reducing equivalents - electrons are sometimes released, sometimes required
32
What is the most common type of reaction in food breakdown (in regards to redox)
Oxidation
33
3 General principles of metabolism
Flow through metabolic pathways is unidirectional and therefore irreversible The first step of the pathway is often the rate limiting step Flow through pathways is regulated
34
What are the 3 energy storages forms in the body
Glycogen Protein Tryglycerides
35
What are the 5 circulating fuels in the body
Glucose Lactose Amino acids Free fatty acids Ketone bodies
36
What are the 3 key metabolic intermediates
Glucose-6-phosphate Pyruvate Acetyl-CoA
37
What is gene regulation of enzyme activity in metabolic pathways
The cell switches the genes that code for specific enzymes on and off Long term control, slow
38
What is feedback regulation of enzyme pathways (2 types)
Feedback inhibition - end product of a pathway interacts with and “turns off” an enzyme earlier in the pathway, preventing a cell from synthesising more product than is needed (negative feedback) Feedback activation - the end product speeds up production of further product (positive feedback)
39
What is allosteric regulation of enzyme pathways
When a regulatory molecule binds to a site on the enzyme that is not the active site, changing the active sites shape affecting enzyme activity Non-competitive Can either inhibit or activate
40
3 reasons for the importance of enzyme localisation
Enzymes are localised to the specific parts of the cell where their substrates are abundant, increasing efficiency Isolation of certain enzymes in particular regions or organelles, it prevents unwanted reactions occurring in the wrong context Allows for precise regulation of metabolic pathways
41
Are mitochondria inherited maternally or paternally
Maternally
42
____-_________ organelle (contains own ___, which is ______). Mitochondrial ___ (mtDNA) encodes ~___% of mitochondrial proteins.
Semi-autonomous DNA Circular DNA 2.5
43
What are cristae and the functions
The folds of the inner membrane of mitochondria where ATP synthesis takes place by oxidative phosphorylation Where the electron transport chain occurs
44
What is the mitochondrial matrix and its functions
The compartment enclosed by the inner membrane Gel like substance Contains enzymes, mtDNA, metabolic intermediates Site of the citric acid cycle producing NADH, FADH2 and CO2 which donate electrons to the electron transport chain
45
What are the 4 stages in cellular respiration - where does each stage occur, what are the products of each stage, anaerobic or aerobic
Glycolysis - cytoplasm, 2 ATP, 2 NADH, 2 pyruvate, anaerobic The breaking down of pyruvate to an acetyl group - mitochondrial matrix, 1 NADH, 1 CO2, 1 Acetyl CoA, aerobic Citric acid cycle - mitochondrial matrix, 3 NADH, 1 FADH2, 1 ATP, 2 CO2, aerobic Oxidative phosphorylation - electron transport chain in the inner mitochondrial membrane, chemiosmosis, 28-32 ATP, H2O, NAD+ and FAD+, aerobic
46
What are the steps in the electron transport chain
Complex I accepts electrons from NADH - some energy pumps H+ protons into the intermembrane space, then electrons are transferred to ubiquinone (coenzyme Q) Complex II accepts electrons from FADH - electrons are then transferred to ubiquinone (coenzyme Q) From Coenzyme Q, electrons travel to complex III - some energy pumps H+ protons into the intermembrane space, then electrons are transferred to cytochrome C From Cytochrome C, electrons are transferred to Complex IV - some energy pumps H+ protons into the intermembrane space, electrons are transferred to oxygen and water is produced
47
What complexes in the electron transport chain pump H+ protons into the intermembrane space
Complex I, Complex III, Complex IV
48
Explain chemiosmosis
Due to the electron transport chain pumping out H+ protons, this creates an electrochemical gradient. Protons then flow back into the mitochondrial matrix through ATP synthase, an enzyme on the inner mitochondrial membrane, to synthesise ATP This flow of protons provides the energy needed to convert ADP+Pi into ATP
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