22 - Monday, October 17, 2011 Lecture 22 Announcements:...

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

View Full Document Right Arrow Icon
Monday, October 17, 2011 Lecture 22 Announcements: Homework for this week's lectures as in LG for 10/21 and10/24, PLUS PyMOL assignment #7 Carbohydrates End of today's lecture: info about the midterm exam Office hours and review sessions this week will be in the usual rooms at the usual times, except that the prof’s office hours on Thursday 10/20 will run from 8AM - noon. Final exam on 12/12. There will be a make-up final exam at a date AFTER the regularly scheduled exam. There will not be any "special" final exam for this course prior to 12/12, so do not ask for this. And if you know that you have a conflict on this date, there will be a make-up final exam, about which arrangements will be discussed when the dates draws near. Friday's lecture: Principles of carbohydrate structure, linkages; role in energy storage as starch and glycogen polymers; structural role Today’s lecture Carbohydrate structural role and recognition role; Intro to bioenergetics A proteoglycan is a structure of protein-linked glycosaminoglycans . It is mostly carbohydrate, but is also has some protein. (See drawing and pictures, right side of page 165). The high negative charge makes these molecules repel each other. They are the active ingredient in the body’s lubricating fluids, found in joints and in the secretion that is mucus. As to the structural role of proteoglycans, they are important in the extracellular matrix, p. 166. Their strong negative charge and extensive hydration create a porous matrix that allows both small molecules and proteins to diffuse to the cell surface. Unexpectedly, it was found that a chondroitin sulfate proteoglycan that proliferates in damaged tissue is a major block to nerve axon regeneration. Here is a case wherein detailed understanding of underlying carbohydrate structure can be of importance to human health. 3. Recognition role of carbohydrates p. 167 Carbohydrates are not found free on the cell surface. Instead, many proteins and lipids in the outer leaflet of the bilayer carry covalently-bound oligosaccharides or polysaccharides. Note that these carbohydrates are on the cell surface , where they are available for binding by molecules outside the cell. Moreover, carbohydrate binds water well, so carbohydrates tend to be highly exposed. Carbohydrates are linked to proteins either through O-glycosidic bonds, or through N- glycosidic bonds.
Background image of page 1

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

View Full DocumentRight Arrow Icon
. O-glycosides are commonly linked to protein Ser-OH or Thr-OH . N-glycosides are commonly linked to Asn-NH-CO Why are carbohydrates key components of many recognition events? The variety of monosaccharides, the many possible linkages between monomers, and the two anomeric possibilities provide many many ways to have different structures. But, recognition is not well-understood-- it is a subject of active research. Cells can recognize carbohydrates on the surface of another cell.
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.

This note was uploaded on 01/01/2012 for the course BIOMG 3310 taught by Professor Feigenson during the Fall '11 term at Cornell University (Engineering School).

Page1 / 6

22 - Monday, October 17, 2011 Lecture 22 Announcements:...

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