DNA Structure Flashcards
1
Q
what is DNA
A
- a type of nucleic acid
- a macromolecule containing genetic info
- in eukaryotic cells it is found in the nucleus
- in prokaryotic cells it is found in the cytoplasm
2
Q
what are nucleic acids
A
polymers
3
Q
what are DNA monomers called
A
- nucleotides
- many monomers bonded together are called polynucleotide
4
Q
what are nucleotides made of
A
- a phosphate group
- pentose sugar
- a nitrogenous base
5
Q
what are the two types of pentose sugars
A
- deoxyribose (missing an O2 atom)
- ribose (has missing O2 atom)
6
Q
how many nitrogenous bases are there and what are they called
A
- 4 types
- adenine bonds to thymine
- guanine bonds to cytosine
7
Q
what is the phosphodiester bonds
A
the phosphate group bonded to the pentose sugar
8
Q
what does the phosphodiester bond create
A
a sugar-phosphate backbone
9
Q
how are polynucleotides read
A
read from 5’ to 3’
10
Q
DNA polymers
A
- double stranded
- two strands are antiparallel and complementary
11
Q
what are the two strands held together by
A
- hydrogen bonds which forms the double helix shape
- hydrogen bond holds the two strands together like a zipper
12
Q
what does antiparallel mean
A
- one strand of the backbone runs from 5’ - 3’
- second stand runs from 3’ - 5’
13
Q
what does complementary mean
A
- nitrogenous bases on one strand are complementary to bases on the other strand
14
Q
how many bonds does each nitrogenous base form
A
- adenine forms 2 hydrogen bonds with thymine
- guanine forms 3 hydrogen bonds with cytosine
15
Q
how is the double helix formed
A
- phosphodiester bonds form backbone of the DNA ladder
- hydrogen bonds are the rungs of the ladder
- when it is twisted it forms the double helix shape
