Chapter 10.3 Flashcards
primary structure of DNA
refers to- the string of nucleotides joined together by phosphodiester linkages
three components of each DNA nucleotide
sugar
phosphate group
nitrogen containing base
what are the two types of nitrogenous bases?
purine
pyrimidine
name the purines
consist of a 5 member ring attached to a 6 member ring
adenine
guanine
name the pyrimidines
consist of a 6 member ring only
cytosine
thymine
uracil
what is the difference between ribose and deoxyribose?
deoxyribose- (DNA’s sugar)
- has a hydrogen atom (-H) attached to the 2’ carbon atom
- has one fewer oxygen atom overall
- less reactive than RNA, more stable for long term genetic coding
ribose- (RNA’s sugar)
- has hydroxyl group (-OH) attached to the 2’ carbon atom
- more reactive than DNA because of additional oxygen atom
nucleoside
a term referring to a deoxyribose/ribose sugar joined with a nitrogenous base
what makes up the phosphate group?
- phosphorous atom bonded to four oxygen atoms
- always bonded to the 5’ carbon atom of the sugar
- usually carry a negative charge = making DNA acidic
what are deoxyribonucleotides?
nucleotides in DNA containing deoxyribose
ribonucleotides
nucleotides in RNA containing ribose
phosphodiester linkages
Phosphodiester bond connecting two nucleotides in a polynucleotide strand.
connect the 3’ carbon atom of one nucleotide to the 5’phosphate group of the next
-always goes 5’ —> 3’
how many hydrogen bonds do C-G pairs have?
3
how many hydrogen bonds to T-A pairs have?
2
secondary structure of DNA
refers to its 3 dimensional configuration
(fundamental helical structure)
-antiparallel double helix
what are the 3 secondary structures of DNA?
A form
B form -
Z form
what is A-DNA structure?
- forms when less water is present
- right-handed double helix
- shorter and wider than B-DNA
what is B-DNA structure?
Right-handed helical structure of DNA that exists when water is abundant; the secondary structure described by Watson and Crick and probably the most common DNA structure in cells.
what is Z-DNA structure?
Secondary structure of DNA characterized by 12 bases per turn, a left-handed helix, and a sugar-phosphate backbone that zigzags back and forth.
