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Biochemistry > Electron Transport And Oxidative Phosphorylation > Flashcards

Electron Transport And Oxidative Phosphorylation Flashcards

1
Q

. ATP functions

A

. Perform mechanical work
. Transport molecules and ions across membranes
. Drives rxns that would be unfavorable by coupling rxn w/ hydrolysis of ATP

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2
Q

Sources of ATP

A

. Glycolysis (substrate level phosphorylation)

. ETC/oxidative phosphorylation

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3
Q

Most important pathways for tissues using aerobic energy

A

. TCA, ETC, oxidative phosphorylation

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4
Q

most catabolic pathways are associated w/ what location?

A

Mitochondria

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5
Q

Most molecules enter aerobic pathway as ___

A

Acetyl CoA

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6
Q

Oxidative phosphorylation

A

Process where ATP is formed from ADP and P as result of energy obtained from electron transport

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7
Q

Electron transport

A

. Transfer of electrons from NADH or FADH2 to O2 through series of electron carriers

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8
Q

Mitochondria in aerobic energy generation

A

. Outer membrane very permeable
. Inner membrane very impermeable and rich in membrane proteins
. Cristae: convolutions of inner membrane, which inc. surface area
. Contains many catabolic enzymes (TCA, fatty acid oxidation, amino acid degradation)
. ATP exits matrix, ADP enters matrix

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9
Q

Flow of NADH in ETC

A

NADH -> I -> Q -> III -> C -> IV -> O2 (total 10 protons pumped making 2.5 ATP)

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10
Q

Flow of FADH2 in ETC

A

FADH2 -> II -> Q -> III -> C -> IV -> O2 (6 protons pumped for 1.5 ATP)

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11
Q

Complex I in ETC

A

. NADH dehydrogenase
. Accepts reducing equivalents from NADH and passes them to CoQ
. Multiple H+ are pumped out as electrons pass through complex I
. Embedded in inner. Mitochondria Membrane
. Fe-S centers
. Electrons flow from NADH to FMN to FeS to CoQ

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12
Q

CoQ/Ubiquinone in ETC

A

. This is nonpolar, lipophilic carrier (not protein) which diffuses w/in the membrane
. Does NOT pump H
. Accepts reducing equivalents from either complex I or II and passses them to complex III
. Reversibly reduced and oxidized in ETC

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13
Q

Complex II in ETC

A

. Succincate dehydrogenase
. Also in TCA
. Reducing equivalents from this step in TCA pass their electrons directly onto the ETC here
. Embedded in inner mitochondria membrane
. Tightly bound FAD and FeS centers
. Electrons flor from succinctness to FAD to FeS to CoQ
. Accepts reducing equivalents from succinctness and passes them to CoQ
. Does NOT pump H

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14
Q

Cytochromes

A

. Contain iron in heme-like structure

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15
Q

Complex III in ETC

A

. Cytochrome bc1
. Contains 2 hemes, FeS groups, cytochromes b and c
. Multiple H ions pumped out as electrons pass through complex III
. Accepts reducing equivalents from ubiquinone and passes them to cytochrome c

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16
Q

Cytochrome c

A

. Heme-like group
. Water soluble protein loosely assoc. w/ membrane
. Released in apoptosis
. Accepts reducing equivalents from complex III and passes them to complex IV
. Does NOT pump H

17
Q

Complex IV in ETC

A

. Cytochrome a+a3/ cytochrome oxidase
. Contains heme-like group
. Protein interacts w/ oxygen
. Multiple H+ pumped out as electrons pass through complex
. Cyanide and CO inhibit this step
. Tightly assoc. w/ inner membrane
. Accepts reducing equivalents from cyt. C passing them to O2 fo generate water

18
Q

Result of ETC

A

. Proton gradient made across inner mitochondrial membrane

19
Q

Chemiosmotic hypothesis

A

. ETC and ATP synthesis coupled by proton gradient across inner mitochondrial membrane (High H+ outside matrix)
. Proton-motive force drives ATP synthesis
. Change in pH about 1 across inner membrane

20
Q

Complex V in oxidative phosphorylation

A

. ATP synthase
. 2 parts
. ETC generates proton gradient used to power conversion of ADP and P to ATP and mechanical rotation of F1 subunit

21
Q

T/F ETC and oxidative phosphorylation are coupled

A

T, one can’t happened w/o the other

22
Q

Natural uncoupling of EC and oxidative phosphorylation

A

. ETC produces heat instead of ATP

. Occurs in brown fat

23
Q

White adipose

A

. 50% cutaneous, 50% around organs
. Unilocular
. Large cytoplasmic drops of triglycerides w/ few organelles

24
Q

Brown adipose

A

. Expresses UCP-1
. Generates heat
. Most prominent in infants in neck, upper chest, and upper back
. Multilocular
. Many small cytoplasmic drops of triacylglycerol, many mitochondria, more vascularized

25
Q

How many genes are needed for uncoupling proteins

A

5

26
Q

UCP-1

A

. Expressed in brown fat
. Encoded by nuclear gene
. Also known as thermogenin
. Located in mitochondrial inner membrane
. Functions to dissipate the proton gradient so that heat is generated

27
Q

UCP-2

A

. Expressed in adipose tissue, muscle, heart, liver, and pancreatic islets
. Linked to obesity locus in human genome
. Elevations in fatty acids induces UCP-2
. Related to diabetes

28
Q

CP-3

A

Expressed in skeletal muscle

29
Q

UCP-4 and UCP-5

A

. Expressed in brain

30
Q

How UCP-1 functions

A

. Proton binds to ionized fatty acid in mitochondrial matrix
. Transports it outside inner membrane
. Fatty acid binds to an H+ to form neutral species
. Fatty cid returns to matrix where it can release H+ dissipating the gradient and simultaneously generating heat

31
Q

Mitochondrial genes

A

. Resembles bacterial DNA
. Encodes 37 genes
. 13 mitochondrial genes code for proteins involved in oxidative phosphorylation
. Rest code for tRNAs and rRNAS involved in translation

32
Q

Most mitochondrial proteins are encoded by _____ genes

A

Nuclear

33
Q

Mitochondrial DNA malfunctions

A

. no DNA repair mechanism so errors are more common
. DNA errors inc. over time
. Oxidative stress in mitochondria coupled w/ an inability to properly replace damaged proteins results in cumulative loss of function

34
Q

Antioxidants

A

. Vit. C (water soluble)

. Vit E (fat soluble)

35
Q

T/F smoking promotes oxidation

A

T

36
Q

Disadvantages of using O2

A

. ROS resulting from normal electron transport

. Damage linked to cardiovascular disease and Alzheimer’s

37
Q

Apoptosis

A

. Regulated
. Too much results in tissue atrophy
. Cytochrome c release from mitochondria starts intrinsic apoptotic pathway
. Cytochrome c enters pore then mitochondria cytoplasm where it activates a series of proteolytic enzymes (cascades) initiating apoptosis

38
Q

Why carry canaries in coal mines

A

. Die of CO or methane poisoning before it was at lethal levels for humans

39
Q

Methane

A

. Colorless, odorless, tasteless, highly flammable
. Not considered toxic but is harmful
. Can’t displace enough O2 in Thr Aires to be dangerous
. Highly flammable

Biochemistry (64 decks)

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