Term
| What cell structure is continuous with the nucleus |
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Definition
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Term
| What are the two differences between constitutive secretory pathways and regulated secretory pathways? |
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Definition
1. Constitutive = always happening Regulated = controlled by signals
2. Constitutive = same rate
Regulated = varying rate |
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Term
| What material goes through nuclear pores? |
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Definition
mRNA
*Note: Nuclear pores ARE selective as to what materials can and cannot pass through them |
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Term
| What function does the smooth ER play? |
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Definition
| Synthesis and modification of cholesterol as well as synthesis of steroids |
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Term
| Outline the process by which mRNA in the cytosol becomes proteins in the ER lumen. |
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Definition
1. mRNA binds to ribosome
2. translation begins with hydrophobic signal sequence on end
3. SRP (signal recognizing protein) binds to hydrophobic signal sequence
4. SRP/signal sequence complex binds to SRP receptor and transmembrane "plug" opens
5. SRP displaces and protein synthesis continues through the transmembrane channel
6. Signal peptidase cleaves the hydrophobic signal sequence |
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Term
| How does transmembrane protein synthesis differ from normal protein synthesis with respect to the ribosome and ER membrane? |
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Definition
| Along with the hydrophobic signal sequence there is also a stop transfer sequence. This sequence becomes inbedded in the membrane. |
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Term
| What 4 post translational modifications occur in the ER |
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Definition
1. Disulfide bonds form
2. Initiation of glycosylation
3. Protein folding
4. Transfer to GPI anchor |
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Term
| How does bonding occur to the GPI anchor in the membrane? |
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Definition
| the GPI tail attached to synthesized proteins at the site of the hydrophobic start signal cleavage |
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Term
| What are the 3 parts of the Golgi apparatus and what is the purpose of each part? |
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Definition
1. cis network - borders ER, receives proteins from the ER
2. medial - modification of proteins
3. trans - sorting and transportation of modified proteins to specified locations via vesicles
*Note: All 3 of these section are biochemically different from each other. They all modify proteins in different ways. |
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