Nucleic acids Flashcards
DNA and RNA are both polymers of _________
nucleotides
what are the 3 components in a nucleotide
- phosphate group
- pentose
- nitrogen containing base
describe the structure of a DNA nucleotide
- phosphate group
- 5 carbon pentose sugar called deoxyribose
- one of 4 nitrogen bases
what are the 4 bases in a DNA nucleotide
- adenine
- cytosine
- guanine
- thymine
describe the structure of an RNA nucleotide
- phosphate group
- 5 carbon pentose sugar called ribose
- one of 4 nitrogen bases
what are the 4 bases in an RNA nucleotide
- adenine
- cytosine
- guanine
- uracil
what is the diffeence between bases in DNA and RNA
in RNA uracil replaces thymine
how are dinucleotides formed
- condensation reaction
- between the phosphate group (5’ end) of one nucleotide and the ribose (RNA) or the deoxyribose (DNA) (3’ end) of another
- the bond formed is called a phosphodiester
- one molecule of water is produced
how are polynucleotides formed
- more nucleotides are added by condensation reactions
- many phosphodiester bonds form and these bonds form the sugar-phosphate “backbone” which is stable and strong
- nucleotides can only be added in a 5’ - 3’ direction
name the molcule that catalyses the joining of nucleotides in the following:
1. DNA
2. RNA
- DNA polymerase
- RNA polymerase
describe the structure of a DNA molecule
- double helix with two polynucleotide chains held together by hydrogen bonds between specific complementary base pairs
- both polynucelotide strands run in opposite directions, this means they are antiparralel
what bonds and how many are formed between these base pairs:
1. adenine and thymine
2. cytosine and guanine
- 2 hydrogen bonds
- 3 hydrogen bonds
what is the function of DNA
hold genetic information
explain how this structure feature helps the function of DNA:
- sugar phosphate backbone and double helix structure
- provides strength and stability
- protects information coded in the bases