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Learn the toughest concepts covered in Microbiology with step-by-step video tutorials and practice problems by world-class tutors.

6. Cell Membrane & Transport

Group Translocation



Group Translocation

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In this video, we're going to begin our introduction to group trans location. And so group trans location is a special type of transport across the membrane where a molecule is going to be chemically modified as that molecule is making its way into the cell as it enters the cell. Now typically group trans location is going to result in the addition of a phosphate group from a high energy molecule to the molecule that's entering the cell. Now the modification to the molecule that's entering the cell allows the entering molecule to always be transported down its concentration ingredient from high to low. And really group trans location is a transport process that is exclusive to bacteria. And so really only bacteria perform group translocation. So let's take a look at this image down below which is showing you an example uh specifically of the E. Coli fossil transfer a system or P. T. S. System which transfers glucose into the cell and converts that glucose into glucose six phosphate as glucose is being transported into the cell. And so if we take a look at this image here, notice that glucose is being represented by these green hexagons. And so here we have our biological membrane and we have a transporter here within the membrane. And so notice that glucose here as it is entering into the cell. It is being chemically modified. And notice that this high energy molecule here, which we can label here as a high energy molecule uh is going to have a phosphate group on it. And that phosphate group will be transported over to glucose as it enters the cell, specifically on glucose, sixth carbon. And so that is why we call this glucose six phosphate. And so as glucose is entering into the cell, it gets chemically modified to become glucose six phosphate. And so this means that the glucose that's on the outside of the cell is still going to be in a higher concentration than it will be on the inside. And that's because glucose is different than glucose six phosphate. And so they're going to have two different chemical gradients. And so um as glucose goes into the cell because it's chemically modified, uh the concentration of just glucose is going to be always lower inside the cell and higher on the outside of the cell, allowing for the cell to continuously be able to uptake glucose. And so basically what we're saying here is that group translocation is a type of membrane transport where a molecule gets modified as it enters into the self. And so sometimes scientists will categorize group trans location as a special or alternative type of active transport simply because a high energy molecule is going to be needed to chemically modify the molecule that's entering. And so this year concludes our brief introduction to group trans location. And so we'll be able to get some practice applying these concepts as we move forward, so I'll see you all in our next video.

Which of the following statements is TRUE about the E. coli phosphotransferase system (PTS)?