ps5 - MIT Biology Department 7.012: Introductory Biology -...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
NAME_____________________________________________________________TA__________________ SEC____ 7.012 Problem Set 5 FRIDAY October 29, 2004 Due to popular demand, and a congenial staff due to the recent performance of the Red Sox, this Problem set upon completion must be inserted into the box Problem sets will NOT be accepted late. Solutions will be posted on the web. Question 1 Viruses have evolved several mechanisms to evade recognition and elimination by the immune system. Our immune systems have likewise evolved ways to counteract these methods of evasion. a) What type(s) of cells of the immune system recognize virally infected cells? b) How do these cells do so? Explain briefly. c) Besides viruses “hiding-out” from most of the immune system within cells, how might viruses further prohibit the previously mentioned immune cells from identifying them in host cells? ** Hint , our immune system has retaliated to this evasion technique with special immune cells called natural killer cells (NK cells for short). These NK cells recognize and kill cells that have low or no MHC class I expression at their surface. It turns out NK cell activity is a little more sophisticated. NK cells do not kill cells that have MHC I receptors on their surface. Cells without MHC I receptors on their surface are candidates for killing by NK cells. But NK cells also need to be activated for killing by specific receptors on the target cell's surface. d) Knowing more about how NK cells function, suggest a way in which the virus may now evade NK cell recognition and thus avoid its subsequent demise. e) In addition, all cells have mechanisms to protect themselves from double stranded RNA ( dsRNA ) viruses. What is this innate mechanism of protection? Briefly explain how it works. MIT Biology Department 7.012: Introductory Biology - Fall 2004 Instructors: Professor Eric Lander, Professor Robert A. Weinberg, Dr. Claudette Gardel
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Question 2 As a UROP in the Weinberg lab, one of your duties is to take care of the mice used for experimentation. During your tenure in the mouse facilities you notice a colony of mice that is highly susceptible to bacterial infections. In order to figure out why, you first take a blood sample and look at the levels of serum proteins. You are shocked to find that these mice lack antibodies in their serum! You are now aware of why they are so
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 7

ps5 - MIT Biology Department 7.012: Introductory Biology -...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online