Term
| Describe the membrane of the mitochondria |
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Definition
1. inner- numerous folds called cristae (increase surface area)
-contains metabolic and transport proteins
-impermeable to ions and small molecules (helps maintain proton gradient)
-electron transport chain occurs here
*ATP synthesis takes place in matrix
2. outer- highly permeable to small molecules
-contains porins which form channels to allow diffusion
3. intermembrane space- similar to cytosol |
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Term
| Describe the dynamic nature of mitochondria |
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Definition
1. constantly fusing and dividing
2. positioned near locations of high energy use
ex. synapse
3. different tissues contain different proteins
-nucleus expresses different genes according to tissue differentiation |
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Term
| Describe the endosymbiotic theory |
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Definition
-it is believed that mitos evolved from bacteria that lived inside larger cells
-mito genome similar to genome of alpha-proteobacteria |
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Term
| Describe the mitochondrial genome |
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Definition
1. circule plasmids
2. multiple copies
3. Encoding
a. only a few proteins for oxidative phosphorylation
b. rRNAs and tRNAs needed for protein coding |
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Term
| Describe the human mitochondrial genome |
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Definition
1. codes for 13 proteins involved in electron transport chain
2. also 16S and 12S rRNAs and 22 tRNAs
3. genetic code is differenet
-U can pair with anything in third position
-some codons specify different AA |
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Term
Describe Mitochondrial DNA mutations
1. How are they inherited
2. Leber's hereditary optic neuropathy |
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Definition
1. almost all mito come from mother's egg, so mutations are passed from mother
2. caused by mutation in genes that code for electron transport chain
-leads to blindness |
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Term
| Describe Mito Protein Transport: Overview |
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Definition
-many mito proteins are coded for in nucleus
-most are synthesized in cytosol and transported
These include: DNA synthesis proteins, tRNA, rRNA, AA, RNA poly
-labeled with presequences |
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Term
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Definition
-amino terminal sequences that guide proteins to mito
-positively charged AA that form amphipathic alpha helix
-presequences are cleaved upon entry into matrix
-bind to receptors on Tom and then Tim
*positive charge brings them to negative inner matrix |
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Term
| Describe Mito Protein Transport: Summary |
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Definition
1. Hsp70 Chaperone keeps protein unfolded
2. Positive preseq binds to Tom
3. to get through inner membrane, electrochemical gradient must be established
-negative inside matrix (pH=8)
4. proteins are ratcheted through (Tim44) using ATP and as they pass through Tim23
5. preseq is cleaved by matrix processing peptidase (MPP) |
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Term
| Describe Mito Protein Transport: Inner Membrane Proteins |
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Definition
-transporters are called Tims
1. proteins contain multiple internal import signals
2. recognized with Hsp90 by Tom70 and translocated across Tom40 channel
3. these proteins are escorted by mobile units of Tim22 called Tiny Tims
4. translocated through Tim22 until stop-transfer signals cause them to exit laterally
*Tiny Tims = transmembrane |
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Term
| Describe Mito Protein Transport: Intermembrane Proteins |
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Definition
1. these proteins contain preseq and internal signal seq
2. translocated through Tom40
a. some stay in outer membrane
b. some remain in intermembrane space |
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Term
| Describe Mito Protein Transport: Oxa1 |
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Definition
1. when preseq is cleaved, some proteins have another seq that targets them for Oxa1
2. Oxa1 is an inner membrane channel that transports proteins back to inner membrane space or inserts in inner membrane
ex. Cytochrome C |
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Term
| Describe Mito Phospholipid Transport |
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Definition
1. imported from cytosol similar to proteins
2. Phospho transfer proteins extract phosphos from ER
3. travel through cytosol and release into mito |
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Term
| Describe Mito Protein Transport: Outer Membrane Proteins |
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Definition
1. Tom40 and beta barrel proteins pass through Tom complex
2. recognized by Tiny Tims and carried to SAM
3. inserted into outer membrane |
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Term
| Describe Mitochondria Lipid Synthesis |
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Definition
1. only makes Cardiolipin
2. double phospho with 4 FA tails
3. very dense and makes inner membrane impermeable to small molecules |
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Term
| Describe Oxidative Phosphorylation: NADH Pathway |
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Definition
*inner membrane of mito
1. electrons from NADH enter in complex I
2. pass to Coenzyme Q (Ubiquinone)
-inside membrane
3. carries to complex 3
-transmembrane
4. transfers from cyto b to cyto c
-peripheral protein
5. carries electrons to complex 4 (cyto oxidase)
-finally transferred to O2 + 2H = H20 |
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Term
| Describe Oxidative Phosphorylation: Overview |
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Definition
1. Electrons from Krebs cycle generated NADH and FADH2 are transferred to O2
2. energy released from these reductions are also used to drive ATP synthesis
-transfer of electrons from NADH to O2= -52.5kcal/mol per pair of electrons
-to harvest this, electrons must pass through carriers |
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Term
| Describe Oxidative Phosphorylation: FADH2 Pathway |
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Definition
1. Succinate gives electrons to complex 2
2. FADH2 receives electrons in complex 2
3. pass electrons on to coenzyme Q
[follows same path as NADH from here]
*no free energy for ATP synthase |
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Term
| Describe Oxidative Phosphorylation: Proton Gradient |
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Definition
-Protons are pumped out by complexes 1 and 4
-coenzyme Q releases H across at complex 3
-pH of matrix = 8
-gradient pulls H+ back in to be used by ATP synthase which is imbedded in membrane
-matrix=neg intermem=pos |
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Term
| Describe Oxidative Phosphorylation: Number of Protons |
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Definition
Number of Protons:
1. Complexes 1 and 3: 4 protons/2 electrons
2. Complex 4: 2 protons/2 electrons
3. 2 protons/2 electrons when combined with O2
*12 H/2 electrons (NADH)
*8 H/2 electrons (FADH2)
4 protons=1 ATP
1 NADH=3 ATP
1 FADH2= 2 ATP |
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Term
| Describe Oxidative Phosphorylation: Chemiosmotic Coupling |
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Definition
Definition: mechanism coupling electron transport to ATP generation
-pumping of H out creates charge/voltage difference
Free Energy:
Electrical potential: G=-FV (F=Faradays constant)
Addition Free Energy relating to [H+] difference
pH gradient: G=RT ln (Hi/Ho) Hi=matrix
V=0.14
Electrochemical gradient= -5kcal/mol H+ |
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Term
Describe Oxidative Phosphorylation: ATP Synthase
1. F0
2. F1 |
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Definition
Two units F1 and F0 that are linked by slender stalk
F0: motor that provides channel for H+ to flow back into matrix
F1: couples ATP synthesis in matrix with energy from H+
-F1 rotates when H+ are passed through F0 |
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Term
| Describe the transfer of ATP/ADP across the Mito Membrane |
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Definition
-ATP has to go out and ADP has to come into matrix
1. ATP (-4) is more negative than ADP (-3)
2. matrix is more basic (more negative)
3. VOLTAGE difference drives ATP out and ADP in |
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Term
| Describe the transfer of P across the Mito Membrane |
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Definition
-Phosphate must come in for ATP synthesis
1. There are more H+ outside so OH- must go out
2. OH- goes out and Phosphate can enter
3. ELECTROCHEMICAL difference drives OH out
*same for Pyruvate |
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Term
| Describe Chloroplasts: Functions |
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Definition
1. Convert CO2 to carbs
2. synthesis of AA, FA, Lipids
3. Reduction of Nitrite (NO2) to NH3
4. ATP ATP ATP! |
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Term
Describe Chloroplasts: Structure
1. Membranes
2. Compartments |
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Definition
1. Double membrane like mito
-also contain 3rd inner membrane
Thylakoid- network of flattened sacs arranged in stacks (grana)
2. 3 distinct compartments
1. intermembrane space
2. stroma (inside intermem but outside thylakoid)
-similar to mito matrix as it contains proteins for ATP
3. Thylakoid lumen= inner membrane
-electron transport and ATP synthase
-pH=5
-chloro need 3 pH difference (1000x H) |
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Term
| Describe the Chloroplast Genome |
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Definition
1. larger and more complex than mito
2. encode for all three RNAs
-tRNAs can translate all mRNAs according to universal code
*codes for subunit of Rubisco
-adds CO2 to Ribbisphos in Calvin Cycle |
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Term
| Describe Protein Transport into Chloroplast |
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Definition
1. Guidance complex recognizes transit peptide (sig seq)
2. Directs to Toc on outer membrane and bind to Toc34/159 (GTP GTP GTP)
-Hsp70 keeps proteins unfolded
-Hsp70 in the inner membrane pulls proteins through
3. proteins then enter Tic and are pulled through by Hsp100
4. Transit peptide is cleaved by Stromal processing peptidase (SPP)
-protein interacts with Hsp70
-finish folding with Hsp60 |
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Term
| Describe Protein Transport into Thylakoid Membrane |
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Definition
1. proteins contain second siq seq that is exposed after cleavage of transit peptide by SPP
2. enter by three pathways
a. Sec- unfolded proteins with Hsp70 (ATP)
b. TAT- folded (H+ gradient)
c. SRP- transmembrane |
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Term
Describe Plastids
1. Structure
2. Function
3. Types |
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Definition
1. similar to chloroplasts but others don't have thylakoid
-contain same genome
2. carry out different functions but not ATP/photosynthesis
3. Chromoplasts- color
Leucoplasts- no color but storage
(Amylo= starch Elaio=lipids) |
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Term
| Describe the Development of Plastids |
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Definition
1. all develop from Proplastids
2. mature plastids come from others
ex. chromos come from chloros
3. depends on environment and developmental signals
4. if in the dark, proplastids will arrest development and become etioplasts
-can develop into chloros in presence of light |
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Term
| Describe Photosynthesis: Two Stages |
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Definition
1. Light reactions
-energy from sunlight drives ATP snythesis and NADPH with formation of O2
2. Dark reactions
-energy from ATP and NADPH drive glucose synthesis |
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Term
Describe Photosynthesis: Sunlight Energy
1. Absorption
2. Photocenters
3. Reaction centers |
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Definition
1. absorbed by pigments called chlorophylls
-absorption excites an electron to higher energy state
-converts light energy to potential chemical energy
2. collection of hundreds of pigment molecules in thylakoid
-antennae to absorb light
3. accepts excited elec and transfer to elec transport chain
-chlorophyll filters out wavelengths
-only want high energy like blue and red |
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Term
| Describe Photosynthesis: Pathway |
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Definition
1. Photon comes into photocenters to reaction centers
2. excited electron goes to PS2
-hydrolysis forms O2
*Mn required
3. Plasto Quninone
4. Cytochome bf - pumps H+ into thylakoid lumen
5. Plastocyanin
6. additional photons are absorbed to re energize the electrons
7. electrons are passed to Ferrodoxin which couples with NADP reductase
-generate NADPH |
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Term
| Describe Photosynthesis: Number of ATP |
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Definition
for each 2e-: 2 protons at PS2 and 2-4 at cyto bf
since 4 protons = 1 ATP, 2e-= 1 to 1.5 ATP
*cyclic flow yields 0.5 to 1 ATP per pair |
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Term
Describe Peroxisomes
1. Structure
2. Function
3. Synthesis |
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Definition
1. single membrane
-do not contain own genome
-can replicate by division/splitting
2. FA and others are broken down and produces H2O2
-contain catalase to convert H2O2 to water
3. Synthesize the following:
-lipids
-AA Lysine
-cholesterol and dolichol
-bile in liver
-plasmalogen (phospholipid joined by ether instead of ester) |
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Term
Describe Peroxisomes
Assembly |
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Definition
Takes place on rough ER
1. Pex3 and Pex 19 localize in rough ER
2. vesicle buds with Pex3/19
3. vesicles fuse with existing perox or form new perox
4. additional peroxins are synthesized on free ribosomes and imported into peroxisome
*Zellweger Syndrome- protein import is disrupted |
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