CHMI-2227EL Lecture Notes - Lecture 18: Isotopes Of Nitrogen, Cyclobutane, Heavy Strand
27 Jun 2018
School
Course
Professor
Biochemistry - Day 18 2018.03.23.
DNA (Deoxyribonucleic acid)
-The complementary base pairing of DNA
-A in one strand pairs with T and G in one strand pairs with C
-A guanine-cystosine pair (G-C) held together by 3 H bonds
-G-C pair has almost the same shape as A-T bonds with 2 H bonds
-The backbone to backbone distance of an A-T pair (C1’-C1’) is 11.1 A
-The backbone of a G-C pair (C1’-C’1) is 10.8 A
-In the A-T base pair, 2 H bonds are separated by 2.8-3 A
-In the G-C base pair 3 H bonds are separated by 2.9-3 A
Other DNA Structure
-DNA can exist in different forms, depending on the conditions
-When humidity is relatively high, DNA is in the B form (the double
helical form deduced by Watson and Crick)
-When humidity is relatively low, DNA is in the A form
-Both B and A forms involve right handed helices
-Other forms of DNA have been identified in the laboratory
-DNA is called the Z-DNA a left-handed helix
Denaturation of DNA
-Physiochemical properties of DNA
-In certain conditions:
-Hydrogen bonds between base pairs can be disrupted, the
2 strands are no longer held together (the strands separate
as individual ransom coils)
-This process is referred to as denaturation
-Denaturing is promoted by:
-Heat
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
A in one strand pairs with t and g in one strand pairs with c. A guanine-cystosine pair (g-c) held together by 3 h bonds. G-c pair has almost the same shape as a-t bonds with 2 h bonds. The backbone to backbone distance of an a-t pair (c1"-c1") is 11. 1 a. The backbone of a g-c pair (c1"-c"1) is 10. 8 a. In the a-t base pair, 2 h bonds are separated by 2. 8-3 a. In the g-c base pair 3 h bonds are separated by 2. 9-3 a. Dna can exist in different forms, depending on the conditions. When humidity is relatively high, dna is in the b form (the double helical form deduced by watson and crick) When humidity is relatively low, dna is in the a form. Both b and a forms involve right handed helices. Other forms of dna have been identi ed in the laboratory. Dna is called the z-dna a left-handed helix.
