baisics of DNA Flashcards
what was the evidence they used to prove for DNA
evidence from X-ray crystallography experiments
what did crystallography suggest
two polynucleotide strands coiled in a right handed helix
how are bases arranged
two chains running in opposite directions with complimentary base parings
5 properties of DNA
1 - two polynucleotide strands coiled in a right handed helix
2 - strong covalent bonds between nucleotide
3 - polynucleotide strands are complementary - run in opposite directions
4- A T , G C
5 - base pairings held together by weak hydrogen bonds
how many hydrogen bonds do Adenine and Thymine have
2
how many hydrogen bonds do cytosine and Guanine have
3
how many polynucleotide strands are DNA made of
2
whats the shape of DNA
double helix
what is the pentose sugar in dna
deoxyribose
what are the 2 types of bases called
purines
pyramidines
what are the purine groups
adenine and guanine
what are the pyrimidines bases
cytosine and thymine
what is on the outside of the DNA molecule
deoxyribose sugar and phosphate group
how are the 2 strands structure
facing each other pointing inwards
what do the hydrogen bonds between the bases do
maintain the shape of the double helix
what is the name to describe the nucleotide strands
antiparalel
what are DNAs structural elements
- 2 polynucleotide strands in double helix
- pentose sugar is deoxyribose
-deoxyribose and phosphate outside DNA - bases two strands face each other
-very long and thin - nucleotides in one strand are in opposite direction in the complementary strand
why is DNA suited to its function (4)
- very large mol
- very stable mol
- two strands able to seperate as held tog by hydrogen bonds
-base pairs on inside of double helix
where is DNA in eukaryots
enclosed in nuclei of eukaryotic cells
where is DNA in prokaryotes
loose in cytoplasm
what is the 2 main roles of DNA
replication
protein synthesis
what happens if the two strands seperate
2 identical double helix can be formed as each parent strand acts as a template for the synthesis of a new complimentary strand
What are the 2 types of bases?
purine
pyrimidine
what are the purine bases of DNA
guanine
adenine
what are the pyrimidine bases of DNA
cytosine
thymine
where is DNA in eukaryot cells
nuclei
where is DNA in prokaryots
loose in cytoplasm
