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Biological Sciences BS22002 > METABOLISM > Flashcards

METABOLISM Flashcards

1
Q

CATABOLISM

degradative/biosynthetic?
oxidative/reductive?
energy released/needed?
converging/diverging?

A

degradative
oxidative
energy released [though there are some reactions that don’t]
converging

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2
Q

ANABOLISM

degradative/biosynthetic?
oxidative/reductive?
energy released/needed?
converging/diverging?

A

biosynthetic
reductive
energy needed
diverging

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3
Q

what CONVERGING means in terms of CATABOLISM?

A

all sugars can be catalysed to CO2 and H2O [final products the same]

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4
Q

what DIVERGING means in terms of ANABOLISM?

A

same building blocks, different products

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5
Q

in ideal conditions ____ ATP molecules can be obtained from 1 glucose molecule

A

94 ATP molecules

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6
Q

Chemotrophs are… [def.]

A

organisms that obtain energy by the oxidation of electron donors in their environments

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7
Q

NAD+ and 2H+ is reduced to

A

NADH and H+

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8
Q

FAD and 2H+ is reduced to

A

FADH2

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9
Q

naming of the enzymes is regulated by

A

NC-IUBMB

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10
Q

NC-IUBMB is an acronym for

A

Nomenclature Committee of the International Union of Biochemistry and Molecular Biology

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11
Q

enzyme class: Oxidoreductases

function: _______
example: ______

A

enzyme class: Oxidoreductases

function: enzymes catalysing oxido-reductions
example: Alcohol dehydrogenase

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12
Q

enzyme class: ______

function: Transfer a group onto a substrate
example: ______

A

enzyme class: Transferases

function: Transfer a group onto a substrate
example: UMP kinase

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13
Q

enzyme class: _____

function: ______
example: aminoacyl-tRNA hydrolase

A

enzyme class: Hydrolases

function: Catalyse the hydrolysis of various bond
example: aminoacyl-tRNA hydrolase

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14
Q

enzyme class: Lyases

function: _____
example: _____

A

enzyme class: Lyases

function: Cleave C-C, C-O, C-N and other bonds by other means than by hydrolysis or oxidation
example: pyruvate decarboxylase

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15
Q

enzyme class: ______

function: Catalyse changes within one molecule
example: _______

A

enzyme class: Isomerases

function: Catalyse changes within one molecule
example: DNA topoisomerase

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16
Q

enzyme class: _______

function: ______
example: DNA ligase (ATP)

A

enzyme class: Ligases

function: Catalyse the joining of two molecules with accessory hydrolysis of the diphosphate bond in ATP or a similar triphosphate
example: DNA ligase (ATP)

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17
Q

enzyme name: Kinase

action: _____
example: _____

A

enzyme name: Kinase

action: Transfer of phosphate group
example: Phosphofructokinase

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18
Q

enzyme name: ____

action: Rearrangement of the molecule
example: ____

A

enzyme name: Isomerase

action: Rearrangement of the molecule
example: Isomerase

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19
Q

enzyme name: ____

action: _____
example: ATP synthase

A

enzyme name: Synthase

action: Makes a molecule from parts
example: ATP synthase

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20
Q

enzyme name: Dehydrogenase

action: _____
example: _____

A

enzyme name: Dehydrogenase

action: Removes hydrogen
example: Isocitrate dehydrogenase

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21
Q

enzyme name: ______

action: Removes phosphate from protein
example: _______

A

enzyme name: Phosphatase

action: Removes phosphate from protein
example: Dual specificity phosphatase

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22
Q

list 4 active consumers of glucose (think high metabolism):

A

RBCs
retina
renal medulla
brain

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23
Q

brain consumes _____% of glucose (in a resting person), weights _____% of body mass

A

brain consumes 20% of glucose (in a resting person), weights 2% of body mass

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24
Q

hydroxyl group in a glucose is in the alpha position when…

A

-OH facing downwards

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25
Q

hydroxyl group in a glucose is in the beta position when…

A

-OH facing upwards

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26
Q

monosaccharides include (3)

A

3 C sugars
5 C sugars
6 C sugars

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27
Q

all C 6 sugars have two forms

A

alpha and beta

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28
Q

in fructose it’s not the hydroxyl group that changes the position but …

A

H2OH

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29
Q

list disaccharides (they don’t want lactose here)

A

sucrose
maltose
cellobiose

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30
Q

sucrose - composition & linkage [imagine drawing them]

A

⍺-D-glu + fru (in alpha position ) 


⍺-1,2 glycosidic linkage

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31
Q

maltose - composition & linkage [imagine drawing them]

A

⍺-D-glu + β-D-glu


⍺-1,4 glycosidic linkage

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32
Q

cellobiose - composition & linkage [imagine drawing them]

A

β-D-glu + β-D-glu


β-1,4 glycosidic linkage

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33
Q

list polysaccharides + say if linear (L) or branched (B) structure

A

cellulose (L)
starch (B)
glycogen (B)

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34
Q

orientation of hydroxyl group in cellulose

A

in turns, i.e. up, down, up, down…. [can start/end with either of the two]

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35
Q

starch and glycogen are both _____ polysaccharides
they form _____ and _____ bonds
the bonds require _____ (same/different) enzyme to break them

A

branched
C1-C6 and C1-C4
the bonds require different enzyme to break them, i.e. one for C1-C6 and another one for C1-C4

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36
Q

how is glucose transported into the cell? (2)

A

ACTIVELY via Na+/glucose symporters

PASSIVELY via passive facilitated diffusion through glucose transporters aka GLUTs 🤧🤧🤧

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37
Q

symport [def.]

A

channel in a membrane that transports 2 different molecules in the same direction across the membrane; does NOT require energy

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38
Q

antiport [def.]

A

channel in a membrane that exchanges ions

DOES requires energy

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39
Q

tissue: brain
GLUT name: _______
characteristics: _______

A

tissue: brain
GLUT name: GLUT1 and GLUT3
characteristics: low Km [affinity]

40
Q

tissue: ______
GLUT name: GLUT2
characteristics: __________

A

tissue: liver (pancreatic β cells)
GLUT name: GLUT2
characteristics: high Km [affinity], insulin independent

41
Q

tissue: _________
GLUT name: ______
characteristics: insulin dependent

A

tissue: adipose tissue, muscles
GLUT name: GLUT4
characteristics: insulin dependent

42
Q

tissue: gut
GLUT name: ______
characteristics: _______

A

tissue: gut
GLUT name: GLUT5
characteristics: fructose transport

43
Q

explain transport of glucose via GLUT1

A
  1. Binding of glucose to the outside triggers a conformational change so that the binding site faces inwards.
  2. Glucose can be released in the inside.
  3. Conformational change regenerates the binding site on the outside.
44
Q

draw glycolysis pathway

A

:) refer to printed materials

45
Q

if both needs (_________ and _________) are met we shouldn’t produce more of pyruvate, so to monitor a reaction, an irreversible step should be chosen as a control point (so you can’t go back)

A

if both needs (production of ATP and provision of building blocks for synthetic reactions) are met we shouldn’t produce more of pyruvate to monitor a reaction, an irreversible step should be chosen as a control point (so you can’t go back)

46
Q

how many control points are there?

A

3

47
Q

first control point (reaction + enzyme)

you MUST know the enzymes

A

glucose + ATP —> glucose 6-phosphate + ADP + H+

HEXOKINASE

48
Q

second control point (reaction + enzyme)

you MUST know the enzymes

A

fructose 6-phosphate + ATP —> fructose 1,6-bisphosphate + ADP + H+
PHOSPHOFRUCTOKINASE

49
Q

third control point (reaction + enzyme)

you MUST know the enzymes

A

phosphoenolpyruvate + ADP + H+ —> pyruvate + ATP

PYRUVATE KINASE

50
Q

which enzyme is key in the control of glycolysis?

A

PHOSPHOFRUCTOKINASE (2nd control point)

51
Q

what happens to ΔG as glycolysis progresses?

A

ΔG 🔽

52
Q

PHOSPHOFRUCTOKINASE can be modulated by several factors

list and briefly explain (where appropriate) the NEGATIVE MODULATORS:

A
  • ATP
  • citrate – early intermediate in citric acid cycle, biosynthetic precursors are abundant
  • H+ – prevents excessive formation of lactic acid
53
Q

PHOSPHOFRUCTOKINASE can be modulated by several factors

list the POSITIVE MODULATORS:

A
  • AMP

* fructose 2,6-bisphosphate

54
Q

energy charge is…

A

the ratio of ATP/AMP

55
Q

the cell is fully charged when…

A

all adenylate nucleotides are in the shape of ATP

56
Q

the cell is discharged when…

A

it only contains AMP and Pi

57
Q

the AMP and not ADP is the positive regulator because…

  • if ATP is rapidly used up …
  • adenylate kinase can rescue some of the energy in the form of…
A

if ATP is rapidly used up … ATP -> ADP + Pi
… adenylate kinase can rescue some of the energy in the form of ADP
2 ADP -> ATP + AMP

58
Q

2 ADP ->

A

2 ADP -> ATP + AMP

59
Q

Anaerobic respiration (2):

A

alcoholic fermentation

lactic acid fermentation

60
Q

alcoholic fermentation =

A

yeast and some microorganisms can form ethanol from pyruvate

61
Q

lactic acid fermentation =

+who?

A

some microorganisms and humans can convert pyruvate to lactate

62
Q

Aerobic respiration = pyruvate is…

A

further oxidised, and much more energy is released

63
Q

what is the lactic acid fermentation equation?

A

C6H12O6 + 2 ADP + 2 Pi —> 2 lactic acid + 2 ATP

64
Q

2 pyruvate are converted into 2 lactic acid molecules by [enzyme]

A

lactate dehydrogenase

65
Q

ADP and Pi are (okay/toxic)

A

toxic

66
Q

where is lactic acid fermentation used…

A

cheese production!

67
Q

muscles sore after anaerobic respiration due to…

A

low pH

68
Q

training at the gym gives 3 benefits:

A
  • Diminishes lactate production
  • Increases lactate clearance
  • Endurance runners have completely different threshold than sprint runners and non-athletes
69
Q

Plasma lactate during exercise predicts….

A

endurance performance

70
Q

what is the alcoholic fermentation equation?

what enzyme?

A

C6H12O6 + 2 ADP + 2 Pi —> 2 ethanol + 2 CO2 + 2 ATP

alcohol dehydrogenase

71
Q

how is pyruvate converted into acetyl-CoA?

pyruvate enters _________ via a specific transporter

there, the _______ complex (___) catalyses the oxidative decarboxylation of pyruvate to acetyl-CoA

A

pyruvate enters mitochondria via a specific transporter

there, the pyruvate dehydrogenase complex (PDC) catalyses the oxidative decarboxylation of pyruvate to acetyl-CoA

72
Q

PDC consists of:
3 enzymes involved in the actual reaction mechanism …

plus 2 enzymes involved in the control of PDC…

… plus 5 coenzymes

A

E1, E2 and E3

a kinase and a phosphatase in a single polypeptide

thiamine, lipoic acid, coenzyme A, FAD, NAD+

73
Q

the activity of the PDC is the major determinant of glucose oxidation in well oxygenated tissues in vivo

The reaction is _____ (reversible/irreversible) aka Acetyl-CoA _______ (can/cannot) be converted to pyruvate

A

IRREVERSIBLE

CANNOT!

74
Q

one molecule of glucose undergoes how many TCA cycles?

A

2

75
Q

Krebs cycle can be also called (2):

A

the citric acid cycle

tricarboxylic acid cycle

76
Q

state the mnemotechnic to remember all the intermediate products of the TCA cycle:

A

A Clown In (alpha)Kilimanjaro Sings Songs For Money Only

77
Q

state the intermediate products of the TCA cycle:

A
  1. Acetyl CoA
  2. Citrate
  3. Isocitrate
  4. α Ketoglutarate
  5. Succinyl CoA
  6. Succinate
  7. Fumarate
  8. Malate
  9. Oxaloacetate
78
Q

state the enzymes catalysing reactions of the TCA cycle:

A
  1. citrate synthase
  2. aconitase
  3. isocitrate dehydrogenase
  4. α-ketoglutarate dehydrogenase
  5. succinyl thiokinase
  6. succinate dehydrogenase
  7. fumarate
  8. malate dehydrogenase
79
Q

each TCA cycle:
uptake of ___ [number] carbon atoms in the form of _____ [substance], and release of ___ [number] carbon atoms in the form of _____ [substance]

A

2, acetyl-CoA

2, CO2

80
Q

each TCA cycle:
___ [number] pair(s) of electrons is/are transferred in the form of NAD+ to form NADH + H+, and
transfer of ___ [number] pair(s) of electrons to reduce FAD to FADH2,
there is also ___ [number] GTP molecule(s) formed from GDP and Pi

A

3, 1, 1

81
Q 
from each acetyl-CoA, the TCA cycle generates:
🍍\_\_x NADH + H+
🥝\_\_x FADH2
🍊\_\_x GTP (GTP + ADP --> GDP + ATP)
🍇 \_\_x CO2
A

3
1
1
2

82
Q

high ATP, NADH and acetyl-CoA = ? [energy]

A

plenty of energy

83
Q

high ADP and NAD+ = ? [energy]

A

lack of energy

84
Q

high succinyl-CoA and acetyl-CoA = ?

A

plenty of precursor molecules for biosynthetic reactions

85
Q

chemiosmosis [def.]

A

movement of ions down their [ ] gradient through the selectively permeable membrane; here it’s H+

86
Q

Electrons flow ____ the electron transport chain from ________ to more ______ redox potential

A

down
negative
positive

87
Q

Big jumps in redox potential equate to ___ which can be harnessed (=take advantage of)

A

big changes in ΔG

88
Q

Chemiosmotic hypothesis (proposed by Peter Mitchell, 1961, chemiosmotic hypothesis) consists of two stages:

A 
electron transport (oxidative part)
ATP synthesis (phosphorylation part)
89
Q

details of electron transport (oxidative part)

A
  • electrons flow from NADH and FADH2 to O2
  • collectively known as respiratory chain
  • energy is used to pump H+ out of the mitochondrial matrix
90
Q

details of ATP synthesis (phosphorylation part)

A
  • electrochemical gradient of H+ across mitochondrial inner membrane
  • energy stored in this gradient can be used to synthesise ATP
91
Q

Electron transport and ATP synthesis are catalysed by ________ (same/separate) proton pumps

A

separate - one set of enzymes for protons going in another for protons going out

92
Q

P/O ratio is a measurement of ________
P/O ratio = the number of molecules of inorganic phosphate (Pi) incorporated into ATP per atom of _____
Depends on the substrate which is oxidised

A

the coupling of ATP synthesis to electron transport

oxygen reduced

93
Q

if NADH is oxidised to NAD+
P/O ratio = ___
numbers are empirical and approximate measurements

A

2.5

94
Q

if FADH2 is oxidised to FAD
P/O ratio = ____
numbers are empirical and approximate measurements

A

1.5

95
Q 
FINAL BALANCE (from 1 glucose molecule)
How much ATP can be generated from the complete oxidation of one glucose molecule?

Glycolysis: _ ATP + _ NADH + H+
Pyruvate dehydrogenase: _ NADH + H+
TCA cycle: _ NADH + H+ + _ FADH2 + _ ATP

Total: 4 ATP, 10 NADH + H+, 2 FADH2

Using the P/O ratio:
10 NADH + H+ yield 25 ATP
2 FADH2 yield 3 ATP

1 glucose molecule yields 30-32 ATP molecules (uncertainty bc P/O ratio is just an approximation)

A

Glycolysis: 2 ATP + 2 NADH + H+
Pyruvate dehydrogenase: 2 NADH + H+
TCA cycle: 6 NADH + H+ + 2 FADH2 + 2 ATP

96
Q

OXPHOS diseases

A

OXPHOS diseases
Involve components of oxidative phosphorylation
Common degenerative diseases (happen over time)
Mutations in mitochondrial or nuclear DNA
Pathology usually becomes worse with age
initially, a decreasing number of normal mitochondria may provide enough ATP
with age, spontaneous mutations accumulate
at some point, not enough ATP can be generated
Symptoms usually appear in tissues with highest ATP demands
nervous system, heart, skeletal muscle, kidneys

Biological Sciences BS22002 (3 decks)

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