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Molecular Cell Biology > Lecture #1 > Flashcards

Lecture #1 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is the theory stating that an aerobic protobacterium was engulfed by an ancestral eukaryotic cell, conferring oxidative phosphorylation to the ancestral eukaryotic cell?

A

endosymbiotic theory

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2
Q

what are invaginations in the inner membrane of the mitochondria

A

cristae

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3
Q

what happens inside of cristae

A

oxidative phosphorylation

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4
Q

where does the Krebs cycle, beta-oxidation, and steriodogenesis take place?

A

matrix

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5
Q

what is the main characteristic that makes mitochondria unique?

A

they posses their own DNA

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6
Q

how are mitochondria are derived?

A

from the production of membrane from the smooth ER and fission events of pre-existing organelles

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7
Q

what is present on the inner mitochondrial membrane that is not present in the outer mitochondrial membrane?

A

cardiolipin

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8
Q

how many polypeptides are derived from mitochondrial DNA?

A

13

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9
Q

describe mitochondrial DNA:

A

16 kb circular dsDNA with several copies present

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10
Q

what are the packing structures of mitochondrial DNA called?

A

nucleoids

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11
Q

what does TFAM stand for?

A

transcription factor A mitochondrial

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12
Q

what is mitochondrial DNA fully dependent on?

A

nuclear DNA

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13
Q

why is mitochondrial dna fully dependent on nuclear dna?

A

the machinery needed for its replication, transcription, and translation comes from the nucleus

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14
Q

what is the helicase responsible for unwinding mtDNA allowing for replication?

A

twinkle

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15
Q

how are mitochondria configured in a cell?

A

in a elastic network where individual mitochondria are constantly fusing and dividing

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16
Q

how many genes does mitochondrial DNA encode for?

A

37

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17
Q

describe the two main parts of mitochondrial dna:

A

heavy strand (outer strand) and light strand (inner strand)

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18
Q

where are the vast majority of genes coded for?

A

heavy strand

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19
Q

what is the only gene transcribed by the light strand?

A

ND6

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20
Q

mitochondrial DNA only has __ promotor, making it a _____________

A

1 ; polycistronic transcript

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21
Q

where is the regulation of the abundance of the mitochondrial mRNA, tRNA, and rRNA established?

A

at the post-transcriptional level

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22
Q

proteins encoded by mitochondrial DNA are all part of what?

A

the respiratory chain

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23
Q

what characteristic of mitochondrial proteins does not allow them to be transported via the classical translocons?

A

they are the most hydrophobic proteins

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24
Q

describe the 3’ end of mitochondrial DNA:

A

very short poly A tail

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25
Q

what is unique about the 5’ end in mitochondrial DNA?

A

no capping

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26
Q

what are the three main players in mitochondrial generation?

A

NRF-1&2 (nuclear respiratory factor), PPAr(alpha) and ERRs (estrogen-related receptors)

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27
Q

what is the key function of NRF-1&2?

A

important in the transcription of genes encoding for the subunits of the respiratory chain and for TFAM

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28
Q

what is the key function of PPAR(alpha)?

A

transctiption factor important for the control of the expression of genes of the fatty acid beta-oxidation

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29
Q

what is the key function of estrogen-related receptors?

A

control the TCA cycle genes, respiratory chain genes, and other oxidative phosphorylation-related genes

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30
Q

what is the main regulator of mitochondrial biogenesis?

A

PGC-1alpha

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31
Q

what occurs when PGC-1alpha is increased in both a transcriptional and protein level?

A

it binds to the key three transcription factors promoting both the transcription and translation of mitochondrial genes

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32
Q

what does PGC-1alpha promote besides the transcription and translation of mitochondrial DNA genes?

A

the transcription and translation of nuclear genes encoding for mitochondrial proteins

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33
Q

what are diseases caused by mutations in the mitochondrial DNA

A

primary mitochondrial diseases

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34
Q

besides mutations in mitochondrial dna, what can cause primary mitochondrial diseases?

A

mutations in nuclear genes encoding for mitochondrial proteins

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35
Q

how many pathways exist for the translation of proteins encoded by the nucleus?

A

three

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36
Q

one pathway for the translation of proteins encoded by the nucleus is mediated by what protein?

A

PUMILIO1

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37
Q

where does PUMILIO1 bind to?

A

3’ end of specific mRNAs

38
Q

what does PUMILIO1 allow for?

A

the co-translational import of proteins

39
Q

how are the vast majority of nuclear encoded proteins imported?

A

in a post-translational manner and imported through chaperones

40
Q

where is the vast majority of mitochondrial proteins synthesized?

A

cytosol

41
Q

what are the 5 major protein import pathways into the mitochondria?

A

presequence, cystine rich, beta-barrels, carrier proteins, and alpha-helical proteins

42
Q

what is a presequence?

A

aminoacidic sequence located in the N terminus

43
Q

what is the function of a presequence?

A

unique target that allows for sorting

44
Q

which specific types of proteins use the presequence pathways as their main form of transport?

A

matrix proteins and proteins residing in the inner membrane

45
Q

for what specific types of proteins is a presequence most often NOT present?

A

proteins in the inner membrane space, outer membrane, and a few in the inner membrane

46
Q

what specific type of bond can those proteins with cystine residues create?

A

disulphide bonds

47
Q

where are the vast majority of proteins with cystein-residues folded? Therefore, what type of pre-sequence do they contain?

A

inside the ER; an ER pre-sequence

48
Q

what do proteins that reside in the outer membrane not have?

A

pre sequences

49
Q

what are beta-barrel proteins?

A

very large pores in the membrane that allow for the passage of solutes and ions

50
Q

where are carrier proteins located?

A

inner mitochondrial membrane

51
Q

if there is an alteration of the permeability of the imm, what occurs?

A

permeability transtion leading to apoptosis

52
Q

what is the carrier protein passage dependent on?

A

mitochondrial membrane potential (MMP)

53
Q

how long is the presequence of mitochondrial proteins?

A

15-50 amino acids

54
Q

what does the presequence of mitochondrial proteins form?

A

an amphipathic alpha-helix

55
Q

what recognizes the elements of the amphipathic alpha helix on the receptors of the omm?

A

translocons

56
Q

what occurs when there is alteration of the permeability of the membrane?

A

permeability transition

57
Q

what is the funcitonality of the imm very important for?

A

the mitochondrial membrane potential

58
Q

what category does TOM 40 belong to?

A

beta-barrel proteins

59
Q

what type of amino acids does TOM40 contain?

A

both hydophilic and hydrophobic

60
Q

when approaching the omm where does the protein bind first, and then where does it enter after?

A

TOM20 then TOM40

61
Q

what are the translocons of the inner mitochondrial membrane?

A

TIM complexes

62
Q

a presequence is followed by a hydrophobic stretch, which signals for what?

A

signals for the protein to be laterally sorted into the inner membrane

63
Q

describe the TIM23 SORT pathway:

A

related to the proteins that are highly hydrophobic and reside in the inner membrane

64
Q

describe the TIM23 MOTOR pathway:

A

regards the proteins that are translocated into the matrix (aka the soluble proteins)

65
Q

what is another name for mitochondrial membrane potential?

A

protonmotive force

66
Q

what are the two components of the protonmotive force?

A

membrane potential and pH

67
Q

what is the exact value of the mitochondrial membrane potential?

A

-180mV

68
Q

what is used to measure the mmp in cells? And specifically, which one?

A

potential metric dyes ; TMRM

69
Q

what is used to ensure that the mpp is being measured and not the plasma membrane potential instead?

A

uncouplers

70
Q

what is an example of an uncoupler?

A

FCCP

71
Q

what does the mitochondrial membrane potential directly activate on the imm?

A

TIM23 complex

72
Q

what complex assists TIM23 in sorting a presequence-containing protein into the matrix?

A

presequence translocase-associated motor (PAM)

73
Q

for those proteins containing a hydrophobic stretch, what serves as the gate keeper in TIM23 which allows them to be sorted laterally into the imm

A

Mgr2

74
Q

what removes the presequence and folds a protein once it has entered into the mitochondrial matrix?

A

mitochondrial protease peptide (MPP)

75
Q

what does the MPP do to proteins that have been translocated into the imm?

A

cleaves their presequences

76
Q

what chaperone family is prevalent in the mitochondrial matrix that helps proteins fold?

A

Hsp60

77
Q

where is Oxa1 located?

A

imm

78
Q

what is the main function of Oxa1?

A

involved in the insertion of mtDNA-encoded proteins into the imm

79
Q

what is the function of Oxa1 in regards to nuclear encoded proteins?

A

sorts proteins located on the imm that possess many transmembrane domains

80
Q

what are the three main characteristics of carrier proteins?

A

they are very hydrophobic, contain 6 transmembrane domains, and do not have a presequence

81
Q

what are the two main carrier proteins?

A

pyruvate carrier and ANT carrier

82
Q

what are pyruvate and ANT carrier responsible for transporting across the inner membrane?

A

pyruvate, ATP, ADP

83
Q

where are the only two places cysteine-rich precursors are found?

A

intermembrane space and the ER

84
Q

what is the function of the MIA complex?

A

oxidizes cysteines in order to form a disulphide bond and allow a protein to reach its final folded conformation

85
Q

which part of the MIA complex is responsible for carrying out the reaction to form the disulphide bond?

A

Mia40

86
Q

the TOM40 channel is an example of which type of import protein?

A

beta-barrel protein

87
Q

what is the most important metabolite channel of the outer membrane?

A

VDAC

88
Q

describe VDAC:

A

voltage dependent, anion-selective channel important for the internalization of metabolites

89
Q

what is the sorting and assembly machinery for the outer membrane which works in tandem with TOM40?

A

Sam50

90
Q

what is responsible for inserting alpha-helical proteins into the omm?

A

MIM complexes

Molecular Cell Biology (10 decks)

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