2.6 Structure of DNA and RNA Flashcards
What are nucleic acids?
The genetic material of the cell
What are nucleic acids composed of?
Nucleotides
What are the three main components of each nucleotide?
5-carbon pentose sugar
Phosphate group
Nitrogenous base
What shape is a 5-carbon pentose sugar depicted as?
Pentagon
What shape is a phosphate group depicted as?
Circle
What shape is a nitrogenous base depicted as?
Rectangle
What is attached to the central pentose sugar?
The phosphate group and the nitrogenous base
Specifically, what is the nitrogenous base attached to?
The 1’ carbon (right point)
Specifically what is the phosphate group attached to?
The 5’ carbon (left point)
What are the two types of nucleic acids present in cells?
DNA and RNA
What is the more stable form of nucleic acids in cells?
DNA
What is the double stranded nucleic acid?
DNA
What does DNA do?
Stores the genetic blueprint for cells
What is the more versatile nucleic acid in cells?
RNA
What is the single stranded nucleic acid?
RNA
What does RNA do?
Transfers the genetic information for decoding
Where do you find the key differences between DNA and RNA?
In the different composition of DNA and RNA nucleotides
What are the three key structural differences between DNA and RNA?
Number of strands present
Composition of nitrogenous bases
Type of pentose sugar
What is the pentose sugar in DNA?
Deoxyribose
What is the pentose sugar in RNA?
Ribose
What are the four base composition of DNA?
Adenine (A)
Guanine (G)
Thymine (T)
Cytosine (C)
What are the four base composition of RNA?
Adenine (A)
Guanine (G)
Cytosine (C)
Uracil (U)
How many strands of DNA is there?
Two
How many strands of RNA is there?
One
What does the double stranded DNA form?
A double helix
What are nucleic acids linked into?
Single strands
How are nucleic acids linked via?
Via condensation reactions
Where does the phosphate group attach to the sugar of another nucleotide?
At the 3’ hydroxyl group
What is the by product of the phosphodiester bond?
Water
What does successive condensation reactions result in?
The formation of long nucleotide strands
How are the two polynucleotide chains held together?
Via hydrogen bonding
Where does hydrogen bonding occur?
Between complementary nitrogenous bases
What does adenine pair with?
Thymine
What does cytosine pair with?
Guanine
How many hydrogen bonds are between Adenine and Thymine?
Two
How many hydrogen bonds are between Guanine and Cytosine?
Three
What must the strands be doing in order for the bases to be facing each other and able to pair?
The strands must be running in opposite directions
What do the atoms do as the antiparallel chains lengthen?
The atoms will organise themselves into the most stable energy configuration
What does the atomic arrangement result in?
The double stranded DNA in a double helix
Who proposed the structural organisation of the DNA molecule?
Watson and Crick
What did the model of watson and crick show?
DNA strands are anti parallel and a double helix
DNA strands pair via complementary base pairing
Outer edges of bases remain exposed
What were the errors of the first trials of watson and crick?
a triple helix
bases were on the outside and sugar phosphates residues in the centre
Nitrogenous bases were not configured correctly and did not show complementarity
What did the final construction of a correct DNA molecules owed to?
The xray crystallography data created by rosalind franklin
What did Franklins data confirm?
The arrangement of the DNA strands into a helical structure
What was the scandal behind Rosalind frankiln?
The data was shared without her permission and massively contributed to the final design
