lecture 4 - denaturation and annealing of DNA

17 slides

what are 3 points of hydrogen-bonding interactions?

1. 2 bases can hydrogen bond to form base pair

2. for monomers, a large number of base pairs is possible

3. in polynucleotides, only a few possibilities exist

what is hydrolysis of nuclein?

phosphate, pentose, nitrogenous base

what is chemical analysis of DNA?

phosphodiester linkages, pentose is ribofuranoside

what did Watson and Crick find in double helix?

• missing layer means alternating pattern (major or minor groove)

• hydrogen bonding: A + T; C + G

what did franklin and wilkins find in double helix?

• cross means helix

• diamonds mean that phosphate-sugar backbone is outside

• calculated helical parameters

what are 4 factors of A form DNA?

1. favoured in non-aqueous solutions (dehydrated)

2. thicker than B form

3. shorter distance between bases

4. right-handed

what are 2 factors of B form DNA?

1. right-handed

2. predominates in-vivo

what are 5 factors of Z form DNA?

1. left-handed

2. takes zig-zag appearance

3. more slender

4. elongated

5. comprises of alternating purine and pyrimidine regions

what are the 3 steps of replication of genetic code?

1. strand separation occurs first (helicase)

2. each strand serves as a template for the synthesis of new strand (DNA polymerase)

3. newly made DNA molecule has one daughter strand and one parent strand (semi-conservative replication

what are 5 factors of mRNA?

1. is synthesized using DNA as template and generally occurs as single strand

2. contains ribose instead of deoxyribose

3. contains uracil instead of thymine

4. one mRNA may code for more than one protein

5. together with tRNA, transfers genetic info from DNA to proteins

what are palindromes?

words of phases that are same when read backward or forward

what is palindrome sequence?

sequence of double stranded nucleic acids with 2-fold symmetry

to superimose, 1 repeat on other, 180 horizontal rotate then 180 vertical rotate

what is mirror repeat sequence?

symmetric sequence within each strand

superimposing requires 1 single 180 rotation