BIOLOGY 2B03 Lecture Notes - Lecture 4: Peroxisome, Cytosol, Mitochondrion

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turquoiseant391

11 Mar 2012

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After proteins have been translated, they can take two pathways: Post-translational: after translation is complete, the signal sequence is translated last which then transports the protein to a targeted location. Co-translation: while translation is occurring, transportation occurs simultaneously. Both of these pathways are regularly used by cells. Before getting into how transportation of proteins occurs in mitochondria or peroxisomes, defining the 5 characteristics of the transportation pathway are important. Receptor for the signal (located on the target) A path for the targeting proteins leading to the different locations within an organelle. Oxidative and synthetic reactions (break down of fatty acids, catalase breaks down hydrogen peroxide. Animal cells: cholesterol synthesis, oxidation of fatty acids. Breakdown/oxidation of fatty acids to acetyl coa produces metabolic energy (plants and animals) This protein is then imported to a peroxisome. The peroxisome grows, and then divides, creating more peroxisomes. This pathway was found using luciferase, which fluorescently labels the catalase enzyme.

Related Questions

1. What biochemical feature of a phospholipid molecule allows phospholipids to spontaneously form closed compartments when placed in an aqueous solution?

a) they are amphipathic

b) they are charged

c) they are spherical

d) they have a single fatty acid tail

2. Other than phospholipids, what molecule do cells use to alter the fluidity of biological membranes?

3. What distinguishes active transport from passive transport?

a) active transport can utilize channel proteins

b) passive transport does not utilize carrier/transporter proteins

c) active transport requires the input of energy

d) active transport only occurs at the plasma membrane

4. In the case of active transport, the Na+/K+ pump undergoes a sequence of conformational changes that allows the movement of Na+ and K+ across a membrane against their electrochemical gradients, while in the case of ER protein import SRP undergoes a sequence of conformational changes to allow the signal sequence to interact with the translocation pore. What drives these conformational changes?

a) hydrolysis of a high energy phosphate bond

b) binding of a solute or protein

c) both

d) neither

5. Is protein import into the ER co-transcriptional, or co-translational?

burgundyhyena124

Type I single pass integral membrane proteins:

		undergo posttranslational translocation, have their N-terminalsignal sequence cleaved, and have a stop-transfer anchorsequence
		undergo cotranslational translocation, have their N-terminalsignal sequence cleaved, and have a stop-transfer anchorsequence
		undergo cotranslational translocation, have their C-terminuscleaved, and have a stop-transfer anchor sequence
		undergo cotranslational translocation, have no signal sequence,and carry positive charges on the N-terminal side of the anchor

rubycheetah414

1) Which of the following statements about transport into the mitochondria is FALSE?

a) The signal sequence on proteins destined for the mitochondria is recognized by a receptor protein in the outer membrane of the mitochondria.

b) Proteins that are transported into the mitochondria are unfolded as they are being transported.

c) Transport of proteins into the mitochondria requires SRP and the SRP receptor.

d) After a protein is made in the cytosol it must move through two protein translocators to reach the inner mitochondrial matrix.

2.Which coat protein is involved in vesicle formation during endocytosis â vesicle forms from plasma membrane and fuses with endosomes?

a) COPI
b) COPII

c) v-SNARES d) Clathrin

3. Which of the following statements about vesicular membrane fusion is TRUE?

a) Membrane fusion does not always immediately follow vesicle docking.

b) The interactions of the v-SNAREs and t-SNAREs pull the vesicle membrane and the target organelle together so that their lipids can intermix.

c) NSF and SNAP disassemble the SNARE complex so the SNAREs can be recycled.

d) All of the above are true.

BIOLOGY 2B03 Lecture Notes - Lecture 4: Peroxisome, Cytosol, Mitochondrion

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