Structure of DNA and RNA: Flashcards
What is the structure of DNA?
= two polynucleotides strands
= sugar phosphate backbone on outside
= bases in centre
= double helix
How are the two polynucleotide strands held together?
= hydrogen bonds between bases on opposite strands
= bases on 1 strand are complementary to bases on another strand
=
What are the pairs?
A-T
C-G
= purine pairs with a pyrmidine
= distance between sugar-phosphate backbone is consant all down the DNA molecule
What does it mean how the 2 polynucleotide strands are anti-parallel?
= run in opposite directions
What does the left hand strand look like?
= top phopshate group is attached to carbon-5 of deoxyribose sugar
= at the bottom the OH group is attached to the carbon-3
What does the right hand strand look like?
= carbon 3 OH group at the top
= carbon 5 attached to the phosphate at the bottom
How many hydrogen bonds does G-C make and A-T make?
= 3 hydrogen bonds
= 2 hydrogen bonds
Are the porportions of the bases always the same as eachother?
= Yes.
What is the structure of RNA?
= polynucleotide 1 strand
= pentose sugar: ribose
= Bases: Adenine, Uracil, Cytosine and Guanine
what are some key differences between RNA and DNA?
= DNA: chromosomes Nucleus
= RNA: cytoplasm
DNA: Long molecule
RNA: shorter
DNA: 2 polynucltoeide strands in a double helox
RNA: 1 nucleotide strand
How does the structure of DNA help with its function?
= DNA is in a double helix shape, and is made from 2 strands, allows a large amount of information to be stored
= great number of hydrogen bonds provides strength
= the sugar phosphate backbone provides strength
= there are 2 polynucleotide strands, these can be broken and act as a template for DNA replication, semi-conservative replication
= the complementary base pairing, forming hydrogen bonding, stores information
