Cell Phys Exam 3 (Module 9-13)

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functions of mitochondria

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133 Terms

1

functions of mitochondria

ATP production, cell death, calcium homeostasis, amino & fatty acid metabolism, aging, immunity

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beta oxidation

fatty acid metabolism

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3

mitochondrial matrix

contains mitochondrial genome, ribosomes, and metabolic enzymes

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4

positive charge of MTS is attracted to negative charge of matrix

why must the matrix be negatively charged?

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mitochondrial inner membrane

contains electron transport chain

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mitochondrial outer membrane

contains channels that transport proteins from cytosol into mitochondria

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endosymbiosis

mitochondria were an ancient bacterium that was engulfed by an ancient primitive archaeal cell

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proteome

the complete set of proteins that make up a specific organelle

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9

1%

what percentage of total mitochondrial proteins is encoded by the genome?

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10

99%

percentage of mitochondrial proteins encoded by nucleus

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11

mitochondrial genome

encodes for some of the subunits of the electron transport chain

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F, it only codes for SOME, the rest come from the nucleus

T/F: The mitochondrial genome encodes for all of the subunits of the electron transport chain.

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13

T

T/F: Proteins have sorting signals to target them to specific cell locations

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signal sequences

can be found at the edge or within proteins; very specific due to having specific arrangements & compositions of amino acids that are recognized by specific proteins to bring them to the organelle

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after the entire genome is translated

when do mitochondrial proteins enter the mitochondria?

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16

cytosolic ribosomes

responsible for post-translational translocation

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17

free cytosolic & ER-bound

what types of ribosomes translate proteins?

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18

Green Fluorescent Protein

fluorophore that glows in the presence of blue light; used to find localization signals on proteins; attaching targeting sequence will bring it to where that protein is going to

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aequorin

bioluminescent protein that gives off blue light

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20
  1. specific mitochondrial targeting sequences

  2. specific transporters

what does mitochondrial protein import involve?

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21

mitochondrial matrix targeting sequence

Located at N-terminus of matrix protein; amphipathic helix; must be at beginning of protein sequence; only cleavable

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22

mitochondrial inner membrane sequence

has non-cleavable transmembrane segment & cleavable targeting sequence

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23

T

T/F: It is possible to have only non-cleavable internal sorting sequences in a protein

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24

mitochondrial outer membrane sequence

has non-cleavable internal sorting sequences

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25

TOM (Translocase of the Outer Membrane) complex

recognizes all nuclear encoded mitochondrial proteins through multiple receptors; only recognizes targeting sequence of outer membrane proteins; located in outer mitochondrial membrane; INDIRECTLY inserts protein into outer membrane

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SAM complex

DIRECTLY inserts nucl. encoded mitochondrial proteins into outer membrane through mediation of the TOM complex

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27

TIM22 (translocase of the inner membrane) complex

inserts nucl. encoded mitochondrial proteins into inner membrane

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TIM23 complex

dimer; the transporter that brings proteins into the matrix and the inner mitochondrial membrane

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OXA complex

inserts mito encoded mitochondrial proteins into inner membrane

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mitochondrial targeting sequence

MUST be the first amino acid sequence in the protein

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31

TOM40

central channel that proteins pass through

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TOM20 & TOM22

the receptors recognizing matrix proteins with a MTS (mitrochondrial targeting sequence)

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TOM20

recognizes hydrophobic side

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34

TOM22

recognizes positively charged side

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35

TIM50

first receptor to bind incoming matrix protein as it passes thru TOM40

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36

until the stop-transfer sequence is recognized

when an inner membrane protein reaches the TIM channel, it will travel thru until when?

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37

cytosolic hsp70

makes sure protein is linear1

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38

mitoHSP70

chaperone that binds incoming MTS of matrix protein and pulls it in

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peptidase

what cleaves MTS?

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40

mitochondrial and nuclear genomes

encode mitochondrial inner membrane proteins

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41

2

there must be how many import pathways for inner membrane proteins?

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42

Path A

import pathway for nuclear encoded mito inner membrane proteins

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43

nuclear encoded mito inner membrane proteins

have MTS & a hydrophobic stop-transfer sequence

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44

Path B

import pathway for mitochondrial-encoded mito inner membrane proteins

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45

through genome and ribosomes

how do mitochondria translate ETC subunit proteins?

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46

OXA1 complex

transports mitochondrial-encoded proteins into inner membrane

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OXA1 targeting sequence

contained in mitochondrial-encoded mito inner membrane proteins and found in genome-encoded proteins

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48

T

T/F: All outer membrane proteins come from nuclear genome

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F

T/F: TOM complex directly inserts the protein into the outer membrane

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50

T

T/F: SAM complex directly inserts an outer membrane protein into the outer membrane

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51

nucleus

largest organelle; contains chromatin (DNA)

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nuclear envelope

double membrane (outer & inner); selective transport of molecules in & out of nucleus; contains nuclear pores

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nuclear pores

used to transport molecules between nucleus & cytoplasm

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nuclear lamina

on the inner side of the inner membrane; support structure

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nucleolus

major site of ribosome biogenesis

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nuclear envelope outer membrane

contiguous (merged) w/ ER

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passive diffusion

Process by which molecules move across a cell membrane from an area of higher concentration to an area of lower concentration without the use of energy

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active diffusion

molecules move across membrane from high to low concentration using ATP

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passive

proteins smaller than 40 kDa can move in & out of the nuclear pore via ___ diffusion

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active

larger proteins move in & out of the nuclear pore via ___ diffusion

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terminal structures

extend on either end of nuclear pore

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docking

attachment of proteins to the nuclear pore; energy independent

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transport thru nuclear pore

requires energy, is selective & requires regulation

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nuclear localization sequence

dictates nuclear import; sorting sequence that targets proteins to nucleus

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basic residues of NLS

Arginines/R & Lysines/K

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necessary

proteins would only go to cytoplasm & not nucleus without NLS

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sufficient

NLS can drive localization to the nucleus by putting it w/ GFP

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importins

recognize NLS (localization)

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exportins

recognize NES (export)

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GTPases

control whether a protein is imported or exported

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guanine nucleotide exchange factor (GEF)

exchange GDP for GTP

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72

T

T/F: every protein w/ a NES inherent has an analyze sequence because an analyze sequence is required for import

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ran GTPase

GTP bound in nucleus

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ran GTPase during import

allows release of cargo from importin in nucleus

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ran GTPase during export

binding needed for exportin to bind NES-containing cargo proteins

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ran GAP

causes ran GTPase to hydrolyze GTP to GDP which releases cargo; located in cytoplasm

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key to ran GTPase regulation

location of ran GAP and GEF

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ran GEF

in nucleus; needed to have an active ran GTPase to release cargo from importin and to bind export cargo

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Ntf2

used to get ran GDP back into the nucleus after GTP hydrolysis

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80

dual-localized protein

function can be same or different in each cellular compartment

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mitochondrial unfolded protein response (UPRmt)

protein has both MTS and NLS; transcriptional GEP reporter is used to study activity & experimented in worms

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nucleus

all mitochondrial chaperones & proteases are expressed in the ___

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83

ATFS-1

transcription factor that regulates genes that repair mitochondria; during mitochondrial stress it increases expression of chaperones & proteases; has a nuclear export sequence

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import into matrix requirements

ATP hydrolysis & membrane potential

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TIM9 & TIM10

chaperones that assist w/ insertion of outer membrane proteins into the outer membrane

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F: it is only for ran-GDP

T/F: Ntf2 goes back to the cytoplasm for repeated nuclear import of Ran-GTP

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weaker membrane potential, less ATP & less mitochondrial import

why does the electron transport chain not work for stressed mitochondria?

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F: healthy mitochondria can fuse to unhealthy ones to help out

T/F: mitochondria cannot fuse together

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F: ATFS-1 will be degraded because it’s no longer needed

T/F: Healthy mitochondria will import ATFS-1 and store it for later use

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F: there is a possibility not to express it when stressed

T/F: A worm will not express fluorescent green only when not stressed

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91

cytoskeleton functions

  • Cell support and shape

  • Cell motility

  • Cell polarity

  • Cell engulfment

  • Cell migration      

  • Wound healing

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92

T

T/F: Cytoskeletal components are all protein polymers

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93

characteristics of actin

  • ubiquitous

  • highly conserved

  • abundant

  • multiple isoforms

  • polarized

  • has longitudinal & lateral bonds to strengthen filament

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94

G-actin

units that make up F-actin

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95

plus end of actin filament

where monomers are put on

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minus end of actin filament

where subunits fall off

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97

actin monomer

composed of 2 lobes & a cleft; is an ATPase

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98

T

T/F: ATP hydrolysis is not required for polymerization of the actin filament, but instead is used to regulate the filament

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99

3 phases of actin polymerization

nucleation, elongation & steady state

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100

rapid

is actin elongation slow or rapid?

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