lesson three= properties of nucleic acids

nucleic acids

DNA= deoxyribonucleic acids

RNA= ribonucleic acid

composition of building blocks=

• nitrogenous bases= part that gives identity

• sugar

• phosphate

purines

adenine

guanine

double ring

pyrimidines

cytosol

thymine

uracil

one ring

adenine

contains a NH2

purine

guanine

contains a c=o and NH2

purine

cytosine

contains -nh2 and c=o

pyrimidine

thymidine

two c=o and a ch3

pyrimidine

uracil

two c=o (no ch3)

present in RNA pyrimidine

guanine and cytosine

three h bonds

strong

adenine and thymine

two h bonds

weak

glycosidic linkage

pccurs at the anomeric carbon and N

will have to draw on quiz and exam

nucleic acid and phosphate

nucleotide

dehydration rxn= lose H2O

bind phosphates to the ch2 oh

Hydroxyl= 3’ where the building/m extending

coding (sense) strand

RNA comes from the coding strand and is complementary (just swap t with u)

noncoding strand (anti sense)

opposite of the mRNA

amino acid codes

start codon= AUG

stop codons= UAA, UGA, UAG

will need to make one on the exam, find all the amino acids, looks for start and stop codons

take coding strand and swap t with u then solve

physical- length of DNA

3.4 A= single base

34 A, 10 bases= single turn

coaxial double stranded helix

two nucleotide chains

antiparallel orientation

diameter 20A

distance between bases is 3.4 A

the putch is of 10 bases (one turn = one pitch)

formation of major and minor groves= steric constraints of nucleotide stacking

B form DNA

most common form

phosphate backbone= negative charge= will react with salt, different forms of DNA due to different salt levels

also a and z form, z is opposite direction

DNA is typically in a B form right handed helix

left handed helix

z

right handed helix

b and a

major groves

Rs: C6 and n7

yS: C4 and C5