nucleic acids 3.1.5 Flashcards
structure of nucleotide
phosphate group, ester bond, pentose sugar, glycosidic bond, nitrogenous base
what pentose sugar is in DNA
deoxyribose
what pentose sugar is in RNA
ribose
what are the five bases found in nucleotides
adenine
thymine
cytosine
guanine
uracil
purine structure
double ring
pyrimidine structure
single ring
which bases are purines (double ring)
adenine
guanine
which bases are pyrimidines (single ring)
thymine
cytosine
uracil
what does RNA contain instead of thymine
uracil
what type of bonds are between base pairs
hydrogen
how many hydrogen bonds between cytosine and guanine
3
how many hydrogen bonds between thymine and adenine
2
what does messenger RNA do
brings information from DNA in nucleus to ribosomes in cytoplasm
directs synthesis of polypeptides
what does transport RNA do
transports amino acids to ribosomes
positions each amino acid at correct place on polypeptide chain
what is ribosomal RNA
main component of ribosomes
site of polypeptide synthesis
combines with proteins to form ribosomes
what are the 4 requirements of semi conservative replication
4 nucleotide bases
both strands of DNA
DNA polymerase and DNA helicase
source of energy
what do free floating nucleotides have
3 phosphates instead of 1
what do free floating nucleotides do
lose 2 phosphates when phosphodiester bond forms
they provide energy for the reaction
steps of semi conservative replication
1 DNA helicase breaks H bonds between bases
2 helix unwinds to form 2 single strands
3 both strands act as a template for a new strand
4 free floating DNA nucleotides are attracted to their complementary bases on the template strand
5 condensation reactions join the nucleotides of the new strand together
(catalysed by DNA polymerase)
6 H bonds form between the bases of the template and new stran
which direction can polymerase add nucleotides
moves 3’ to 5’ on the origional strand but forms the new strand from 5’ to 3’
