Colorado Mountain College Biology Diagrams Drawing

Learning Goal: I’m working on a biology exercise and need a sample draft to help me learn.

GENERAL INTRODUCTION

This drawing assignment is to draw out the process of co-translational translocation, glycosylation, and intracellular trafficking of a Golgi transmembrane protein. The full details are below, along with due dates, a checklist that you can use to make sure you include all details required to earn full credit.

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DRAWING DETAILS

For this drawing you will draw all of the steps involved for a polypeptide—that is destined to be a glycosylated transmembrane protein in the Golgi membrane—to be co-translationally translocated into the ER membrane, glycosylated, and then transported in a vesicle to the Golgi.

1. Draw a polypeptide undergoing co-translational translocation. Your drawing should include recruitment of the polypetide and ribosome to the ER membrane during translation. The polypeptide should have an N-terminal signal sequence and one or more subsequent start/stop transfer sequences (this question includes content from Lecture 9 & Learning Module 4/Lecture 12/13—there are images of all details in the slides).

This part of your drawing should include (make sure you label these components):

• the polypeptide (that is destined to become the glycosylated transmembrane protein)
• the signal sequence (on the polypeptide)
• the ribosome
• SRP
• the SRP receptor
• the protein translocator

2. Now draw the polypeptide undergoing N-linked glycosylation (as shown in Lecture 10, slide 9).

This part of your drawing should include (make sure you label these components):

• the transmembrane protein
• oligosaccharyl transferase
• the oligosaccharide (on the transmembrane protein)

3. Now draw your glycosylated transmembrane protein getting trafficked from the ER to the Golgi (you will need to refer to learning module 4 and Lecture 12/13 slides for this part—just do your best!).

This part of your drawing should include:

• budding (with the specific coat protein labeled),
• transport (molecular motor, motor binding protein and cytoskeleton filament track it is “walking” on),
• targeting/tethering (Rab),
• and fusion (SNARE) of the vesicle;
• the different leaflets of the membrane should be colored differently to show that you understand “once cytosolic, always cytosolic.”

Here is an example from a previous semester where the assignment was to draw a soluble protein (so, not membrane bound) being trafficked to the lysosome. Although the assignment was a bit different, this drawing should give you some ideas…especially for Part 3!

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CHECKING YOUR WORK

Use the checklist below to make sure your drawing includes all of the details described above.

Each item on the list is worth 1pt! Each item should be drawn AND CLEARLY LABELLED.

For Part 1:

• the polypeptide (that is destined to become the glycosylated transmembrane protein) – 1pt
• the signal sequence (on the polypeptide) – 1pt
• the ribosome – 1pt
• SRP – 1pt
• the SRP receptor – 1pt
• the protein translocator – 1pt

For Part 2:

• the transmembrane protein – 1pt
• oligosaccharyl transferase – 1pt
• the oligosaccharide (on the transmembrane protein)- 1pt

For Part 3:

• process of budding – 1pt
• the specific coat protein is labeled (meaning you should include either COPI, COPII or Clathrin) – 1pt
• process of transport – 1pt
• molecular motor – 1pt
• motor binding protein – 1pt
• cytoskeleton filament track it is “walking” on – 1pt
• process of targeting/tethering–the process of “targeting/tethering” should be labeled (1pt) and the Rab should be labelled (1pt)
• fusion–the process of “fusion should be labeled (1pt) and the SNAREs should be labelled (on both the vesicle and Golgi – 1pt)
• the different leaflets of the membrane should be colored differently to show that you understand “once cytosolic, always cytosolic.”