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21 Cards in this Set
- Front
- Back
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What are the purposes of organelles? |
- concentrate components of a metabolic pathway - localise, orientate and allow for lateral movement of proteins and protein complexes - contain dangerous or damaging processes |
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What are the features of peroxisome (4)? |
- small, membrane bound - contains oxidative enzymes (catalase) - contains a crystalline structure - found free within the cell or associated with another organelle |
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What are the function of the peroxisome (6)? |
- produces or degrades H2O2 - uses O2 to oxidize organic molecules - it is involved in the glyoxylate cycle - catabolism of long FAs, purines, phenols etc. - detoxification of alcohol (liver) - bile acid formation - Protein import by C-Term SKL motif (Ser-Lys-Leu-COO) |
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What is the glyoxylate cycle? |
- allows cells to utilize simple Ca compounds when complex sources such as glucose are not available - turnover of AcetylCoA to succinate |
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There are two pathways of development and segregation of the peroxisome. What are they? |
- Growth and division - newly synthesised Px proteins and membrane proteins are incorporated into pre-existing or recently divided Pxs - Peroxisome maturation model - px vesicles derived from ER; they fuse together and mature |
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What are the characteristics of semi-autonomous organelles (5)? |
- distinct metabolic functions and structures - genome (circular with unique organelle genes) - has own transcription/translation machinery - distinct biogenesis - self-replicate by binary fission with specific division mechanismnot controlled by cell division and not synthesised de novo |
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What is the structure of the mitochondrion (5)? |
- surrounded by single envelope membranes - contains complex inner membrane with invaginations (cristae) - matrix is physically separate and biochemically distinct from IMS - multi-protein complexes are found in inner and outer membranes, intermembrane space (IMS) and matrix - has a complex protein import system |
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What are the features of the mitochondrion (based on the structure) 6? |
- 1-2 um length - outer membrane is ~ permeable to solutes - inner membrane is impermeable - gap between the two is very small - H+ and enzymes are accumulated in matrix - biochem difference between IMS and matrix drives metabolic functions |
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What are the components of the mitochondrial protein import system? |
- Translocase of outer membrane - TOM - Translocase of Inner membrane - TIM - Matrix processing peptidase (MPP - cleaves off the recognition presequence) |
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How do mitochondria move? |
- via microtubules |
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What is the structure of the chloroplast? |
- surrounded by two envelope membranes - contains complex membrane system (thylakoids) - multi-protein complexes reside in the thylakoid - stroma is physically separate and biochemically distinct from Lumen - complex protein import system |
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What are the two states of the thylakoids? |
- Appressed (lying flat or pressed closely against something) and non-appressed - depends on the way the multi-protein complexes reside in the thylakoid membrane |
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Where are the genes of autonomous organelles kept? |
- in organelle DNA - in Nuclear DNA (proteins are imported) |
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How are the proteins encoded by nuclear DNA imported into the mitochondrion? |
- TOM, TIM and MPP |
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Why are so many proteins encoded by the nuclear genome? |
- overall control - evolution - damage limitation |
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Why are there proteins still encoded by the organelle genome? |
- dont have to import them (save energy) - max production of proteins - rapid turnover - fine/rapid regulation - redox-response control |
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All plastids are derived from a common source. What is that? |
- proplastids |
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What are the steps of Chloroplast division? |
1) division ring associates with the outer and inner envelope membrane 2) dynamin-like protein associates 3) constriction of the division ring 4) isthmus formation 5) separation |
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Chloroplast division (image) |
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Chloroplast division (image 2) |
- aid in alignment of ring - equality of two progeny - constriction of ring - pinching of isthmus |
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Give example of some proteins that regulate chloroplast division: |
1) ARC11 (MinD) and ARC12 (MinE) - control where the division ring forms 2) ARC3 - controls the structure of the ring |
