CMMB 411 - Topic 1 Memory

Purine binds sugar with:

N9

Pyrimidine binds sugar with:

N1

Cytosine tautomer is _____, binds _____

imine/uncommon form, adenine (amine/common)

Guanine tautomer is _____, binds _____

enol/uncommon form, thymine (ketol, common)

Hoogsteen Base pairing through which atoms on ____.

N7, N6, O6 on purines

positive supercoiling = ____wound, ____handed

Twist=     Wr=

overwound (10.5bp< per turn)

left handed

Tw: decrease Wr: increase

negative supercoiling= ____wound, _____handed

Tw=    Wr=

underwound (!10.5> per turn)

right handed

Tw: increase Wr: decrease

Change in Lk=

Change Lk= Lk-Lko

Lko=

Lko= #bp in the molecule/10.5bp

a (density)=

change in Lk/Lko

Topioisomerase type 1:

No ATP, nick on strand (ssDNA), change Lk by 1

Topioisomerase type 2:

Maybe ATP, dsDNA cut, change Lk by 2

Topo 1:

Type 1

relax negative supercoils

Topo 2:

Type 2

Gyrase  *ATP

Induce negative supercoils

Topo 3:

Type 1

DNA damage/repair, and DNA replication
relax + supercoils

Topo 4:

Type 2

Break apart chromosomes

C3’ Endo pucker:

RNA, A-DNA

C2’ Endo pucker:

DNA

purines can be

anti or syn

pyrimidines can be

anti

B DNA

10.5bp/turn

right handed

A DNA

more compact

right handed

deepen major groove

C3’ endo pucker
Dry conditions

Z DNA

less compact

left handed

Zig-Zag (alternate purine/pyrimidine)

regulation in promoters?

Narrow and deeper minor groove