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17 Cards in this Set
- Front
- Back
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Protein synthesis--
Where? How? |
Where? ribosomes in rough ER, cytoplasm, mitochondria, chloroplast
How? mRNA made from DNA, read by ribosome (rRNA), tRNA brings in new amino acids |
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Rationale for protein synthesis
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-replacing old proteins
-adding more for daughter cell created during cell division Proteins are needed in specific locations throughout the cell |
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How do proteins know where to go?
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Proteins have unique AA codes that act as "sorting signals"
-specific organization = specific signal; signal sequence is important Cytoplasm has NO signal sequence--proteins are made there and remain there. |
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How do proteins get inside organelles?
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-nuclear envelope has pores
-other organelles have membrane protein translocators (proteins) -golgi gets proteins via vesicles from ER |
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Nuclear anatomy
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Nuclear pore complex
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~30 different proteins
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Nuclear pore
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made up of various types of proteins
-cytosolic fibers (extended proteins) -ring subunit -nuclear basket/cage made of nuclear fibrils |
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nuclear lamina
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similar to the cell cortex, provides structure for nuclear membrane
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Nuclear pore transport
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-small molecules can pass freely
-large molecules must have correct sorting signal to pass with help of nuclear receptor protein |
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Nuclear receptor proteins
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in cytoplasm
-protein signal binds to transport receptor -importins and exportins -receptor proteins are the ones which actually bind to and are perceived by pore complex. |
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Energy and Nuclear transport
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Need energy for nuclear transport
GTP ->GDP + P + Energy ex: "Ran" binds to GTP, Nuclear receptor proteins bind with Ran for energy GTP = guanosine triphosphate (made in citric acid cycle) |
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Ran
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Binds to GTP for energy in nuclear transport
G protein with two confirmations: -bound to GTP -bound to GDP (after hydrolyzing GTP) |
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G proteins
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Ex: ran; "G-protein" if bind with GTP
G proteins are a member of GTPase superfamily of proteins (guanine nucleotide-binding proteins)(guanine is part of guanosine) -regulate cellular processes w/GTP |
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Nuclear transport cycle
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Ran-GTP binding to nuclear transport receptor releases cargo (changes confirmation)
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Nuclear pores image
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Nuclear transport
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importin
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