quiz1_prep_ho

quiz1_prep_ho - MIT Department of Biology 7.014...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
MIT Department of Biology 7.014 Introductory Biology, Spring 2005 7.014 Quiz I Handout • Below is last year’s Quiz I (solutions at the end). It should give you an idea of the format and types of questions we tend to ask on the exams. There is some difference in covered material and emphasis on various parts of the material between last year’s and this year’s versions of the course. We do not guarantee that this year’s quiz will cover the exact same subtopics. Quiz I announcements: **This will be a closed book exam**
Background image of page 1

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

View Full DocumentRight Arrow Icon
Question 1 (26 points) The protein complex, LETMEGOTHRUIN (LMGT for short), acts as a channel or pore through which charged proteins and ions can cross the phospholipid bilayer of the membrane. LMGT is composed of four polypeptides as shown in Figure A. Figure B shows a cross section of two of the polypeptides. a) What are the characteristics of phospholipids that are crucial to their ability to form lipid bilayers? b) In Figure B, the amino termini (N-termini) are closely associated with the phosphate groups at the surface of the phospholipid bilayer. Name three amino acids that would likely be found at the N-termini of these polypeptides. c) LMGT is composed of four polypeptides (two γ polypeptides and two δ polypeptides). i) How many unique primary protein structures compose the LMGT protein complex? ii) What protein secondary structure is part of the LMGT protein complex? iii) What is the strongest type of bond that maintains the quaternary structure of LMGT? 2 d g S S S S Phospholipid Bilayer Figure B Figure A Membrane N-termini S S Figure by MIT OCW.
Background image of page 2
Question 1, continued d) Describe how the polypeptides of the LMGT protein can be surrounded by non-polar hydrocarbons but allow charged proteins and ions to transit the membrane. e) One of the small molecules permitted to pass through the LMGT channel is PUNY, a tripeptide. PUNY is composed of asparagine-proline-alanine with asparagine at the amino terminus. Draw the chemical structure of PUNY. Circle the peptide bonds. 3
Background image of page 3

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

View Full DocumentRight Arrow Icon
Question 2 (30 points) MIT has produced a time machine that can send a team of undergraduates back in time. The mission commander is expecting you to provide insight into the biology occurring at various time points visited. a) Your first stop is 4 billion years ago where you collect the “primordial soup” containing the precursors of life. You observe a polymer in this “soup” that can copy itself. The mission commander wants to know… i) What is this molecule? ii) She asks you to sketch a single building block of this molecule below. b) Your next stop is 3 billion years ago where you find organisms similar to cyanobacteria that produce glucose from CO 2 using “photosynthesis release 1” (cyclic photophosphorylation).
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 13

quiz1_prep_ho - MIT Department of Biology 7.014...

This preview shows document pages 1 - 5. Sign up to view the full document.

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