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BIOC192 > Final exam > Flashcards

Final exam Flashcards

1
Q

what four macronutrients are in the diet and what are their monomers?

A

proteins- amino acids
carbohydrates- monosaccarides
fats/lipids- fatty acids
nucleic acids- nucleotides

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2
Q

what are three key properties of co-enzymes in metabolic pathways?

A

low concentration in cells
act as carries
have two forms

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3
Q

what 2 types of reaction happens to fuel molecules in the pathway?

A

those involving ADP and ATP
oxidising fuel molecules= releasing lots of energy

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4
Q

what does reducing equivalent mean?

A

moving hydrogen moves an electron, but a proton also moves as well
therefore H+ is referred to as a reducing equivalent= dehydrogenase

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5
Q

carb digestion involves the hydrolysis of _____ bonds catalysed by the enzyme _____ which digests starch into _________

A

glycosidic
amalayse
disaccarides

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6
Q

why are monosaccarides unable to cross the cell membrane unaided?

A

because they’re highly polar and need specific transporter proteins.

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7
Q

what is meant by ‘symport’ transport of glucose by the SGLT1 transporter?

A

glucose and Na+ move into the epithelial cell together
Na+ goes down its concentration gradient passively
glucose goes up its concentration gradient but moves with Na+

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8
Q

which cells of the human body is glucose favoured as a fuel? Why?

A

brain- high energy requirement. glucose easily crosses blood brain barrier. also provides a quick source of ATP without risk of damage

red blood cells- they dont have any mitochondria
the eye- low levels of blood vessels and mitochondria
white muscle cells- fast response with glucose as a fuel

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9
Q

what are the two phases of glyocolysis?

A

energy investment- activation of glucose
energy payoff- making ATP profit

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10
Q

why is ATP hydrolysed in glucose activation?

A

it is coupled with adding a phosphate to glucose to make the reaction energetically favourable

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11
Q

why is the oxidation of glyceraldehyde-3-phosphate essential for glycolysis to make ATP profit

A

the NAD+ is reduced- giving oxidising power
so phosphate from solution can be added to the substrate
and no ATP has been spent

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12
Q

the ATP produced in glycolysis is produced through what type of reaction? what is the key aspect of this type of reaction?

A

a substrate level phosphorylation, phosphate cleaved releases energy. That energy is then used for a substrate level phosphorylation
the coupling of these two reactions results in a energetically favourable reaction

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13
Q

why does arsenate prevent an ATP profit being made in glycolysis?

A

arsenate hydrolyses but energy isnt captured so ATP isnt synthesised by phosphoglycerate kinase= no net gain of ATP.

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14
Q

what is the overall reaction for glycolysis?

A

glucose+ 2NAD+ + 2ADP + 2Pi —-> 2 pyruvate +2NADH + 2ATP + 2H+

delta G= -73kj/mol
therefore pathway is energetically favourable

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15
Q

name two diatary lipids obtained in our diet? Which of them makes up 90% of our dietary fat?

A

sterols
triacylglyerols- 90% of diatary fat \

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16
Q

lipids are made soluble for digestion by ____ acids which act as detergents. They are made from ____, synthesised in the _____ stored in the ____ and secreted into the ____

A

bile
cholestrol
liver
gall bladder as bile
small intestine=

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17
Q

what is a lipoprotein and what is its function?

A

delivery system for transporting lipids around the body. solubilise lipids for transportation in the blood from digestion

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18
Q

what are the four classed of lipoprotein and how are they classed?

A

chylomicrons- TAG transport low protein to lipid ratio
very low density lipoprotein (VLDL)- TAG, medium protein to lipid ratio
Low density lipoprotein (LDL)- cholesterol transport
High density lipoprotien (HDL)-cholesterol regulation

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19
Q

what are two major lipid transport pathways and which lipoprotein is used in each?

A

exogenous- from diet, lipoprotein lipase in endothelial cells on capillary surface
endogenous- recycling in the body, (VDL) very low density lipoprotein

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20
Q

what is the function of the lipoprotein lipase enzyme?

A

to hydrolyse TAG in lipoproteins to monoacylglycerol and fatty acids that enter the tissue
ApoCll activates lipoprotein lipase. Chylomicron reminant remains in the blood

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21
Q

why does the body store fats rather than carbs?

A

because storage of carbs takes up more space as they hold more water.

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22
Q

in terms of ATP hydrolysis what is the cost of activating fatty acids?

A

energy to add Coa from hydrolysis of ATP–> AMP = the energy equivalent of 2 ATP.

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23
Q

how is fatty-acyl Coa transported into the mitochondria?

A

has to pass 2 membranes
outer= fatty acyl-coa carrier
inner= conversion to fatty acid carnitine

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24
Q

what 4 reactions occur in beta oxidation

A

1) oxidation
2) hydration
3) oxidation
4) cleavage

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25
Q

what is the product of beta oxidation?

A

acetyl-coa (further oxidised in the citric acid cycle)

26
Q

what are the two main parts of the citric acid cycle?

A

1) release of carbon
2) regeneration of starting molecule

27
Q

what is a substrate level phosphorylation

A

the direct use of energy from a substrate molecule to drive the synthesis of ATP

28
Q

how are fatty acids activated before beta oxidation?

A

they have a CoA added to them so they become a fatty acyl-CoA
*energy to do this is through the hydrolysis of ATP–> AMP. total energy cost is 2ATP

29
Q

what does the citric acid cycle capture?

A

one ATP
3NADH, 1FADH2

30
Q

what happens if fluroacetate is present in the citric acid cycle?

A

it is metabolised to flurocitrate
but instead of being arranged to citrate it becomes a substrate that binds tightly to aconitase which inactivates the enzyme.

31
Q

what occurs if the citric acid cycle is inhibited?

A

-buildup of acteyl-CoA
-less ATP and less energy captured in reduced coenzymes

32
Q

what is the role of an endopeptidase?

A

cleaves bonds within a peptide

33
Q

what is the role of an exopeptidase?

A

cleaves bonds near the ends of proteins to release amino acids as di/tri peptides

34
Q

what part of peptides does pepsin cleave?

A

aromatics

35
Q

what part of peptides does trypsin cleave?

A

positively charged

36
Q

what part of peptides does chymotrypsin cleave?

A

aromatic

37
Q

what is endopeptidase specificity determind by?

A

the adjacent amino acid side chains

38
Q

what are zygomens and why are they produced?

A

they are inactive forms of proteases. this is to ensure they only work in areas they are supposed to.

39
Q

how is pepsinogen activated

A

an autolytic and catalytic process

40
Q

what activates trypsinogen to trypsin

A

enterokinase on the endothelial cell wall in the small intestine

41
Q

what activated chymotrypsinogen to chymotripsin

A

the activated trypsin.

42
Q

how are amino acids transported into the epithelial cells?

A

through amino acids sodium transporter
Na+ passively down its gradient
amino acids going from low to high concentration (up its gradient)

43
Q

what is transamination?

A

amino acids transferring their amino group to a keto acid.
this is done through an aminotransferase enzyme

44
Q

what is PLP
what is its purpose
what are its two forms
and what is it derived from

A

a coenzyme that is needed for transamination reactions.
it carries an amino group
pyridoxal phosphate= no amino group
pyridoxamine phosphate= with amino group

45
Q

describe the two steps of a transamination reaction

A

1) the amino group is transferred from the amino acid to the pyridoxal phosphate
2) the amino group is transferred from the pyridoxamine phosphate to a keto acid

46
Q

what is the path of NADH in the electron transport chain?

A

Complex I - UQ- complex III- cyt C - complex IV - O2

47
Q

what is the path of FADH2 in the electron transport chain?

A

Complex II - UQ - Complex III - cty c - complex IV - O2

48
Q

what part of the ETC does rotenone inhibit?

A

inhibits the electron transfer from complex I to UQ

49
Q

what part of the ETC does cyanide inhibit?

A

binds to a carrier in complex IV

50
Q

what part of the ETC does carbon monoxide inhibit?

A

binds to where O2 binds

51
Q

what effect do inhibitors have on the outcome of the electron transport chain?

A

they dont allow for a proton gradient to build
get a buildup of reduced enzymes
therefore there is no oxidising power for other pathways

52
Q

what occurs at complex I of the ETC

A

NADH is oxidised
2 electrons put into the ETC
4 protons are pumped for each NADH oxidised.

53
Q

what occurs at complex II of the ETC

A

FADH2 is oxidised
2 electrons put into ETC
No H+ pumped
SDH shared with CAC

54
Q

what does UQ do in the ETC

A

both complex I & II pass their electrons onto UQ
can take electrons one or two at a time to complex III
releases on electron at a time to complex III

55
Q

what occurs at complex III in the ETC

A

passes on one electron at a time to Cyt C
pumps 4H+ across the membrane

56
Q

what occurs as complex IV

A

reduces O2 to H2O
1NADH/FADH2= 2H+
1/2O2+2H+–> H2O
waits until there are 4 electrons so it doesnt work in halves

57
Q

how many protons does NADH pump across the membrane in the ETC

A

10
4-complex 1
4-complex 3
2- complex 4

58
Q

how many protons does FADH2 pump across the membrane in the ETC

A

6
4-complex 3
2- complex 4

59
Q

what is DNP and what impact does it have on oxidative phosphorylation?

A

it is an uncoupler that ruins the established gradient by the ETC. As the gradient is needed for ATP synthesis no ATP is able to be made.
therefore all energy stored becomes heat.

60
Q

whats occuring at the open, tight, and loose conformation

A

open= ADP + Pi binding
tight= catalysis- ATP forming
loose= holds ADP and Pi in prep for catalysis

61
Q

how many atp does 1 NADH produce?

A

4 protons per 1 atp
10 protons=
2.5 ATP

62
Q

how many ATP does 1 FADH produced

A

4 protons per 1 atp
6 protons=
1.5

BIOC192 (5 decks)

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