Structure of DNA and RNA Flashcards
1
Q
What is the structure of nucleotides?
A
- A pentose sugar
- A phosphate group
- a nitrogenous base which is either A,T,C,G
- All components are joined by a condensation reaction
2
Q
How are nucleotides joined together?
A
- phosphodiester bonds form between the deoxyribose sugar of one mononucleotide and the phosphate group of another
- This is a condensation reaction
3
Q
What is a polynucleotide?
A
- Many nucleotides joined in a long chain
4
Q
Who discovered the structure of DNA?
A
Watson and Crick but due to its simplicity many scientists doubted it carried the genetic code
5
Q
What is the structure of DNA?
A
- double helix formed of two polynucleotides joined by hydrogen bonds in complementary bases
- this is A and T and C and G
- phosphodiester bonds between phosphate and deoxyribose forming the sugar-phosphate backbone
6
Q
What is the structure of RNA?
A
- ribose sugar
- phosphate group
- bases ( Adenine and Uracil) and ( Cytosine and Guanine)
7
Q
Compare RNA and DNA
A
- Both consist of a pentose sugar, a phosphate group and 4 nitrogenous bases.
- Both are joined by covalent phosphodiester bonds between the phosphate and pentose sugar groups.
8
Q
Contrast RNA and DNA
A
- DNA is double-stranded whereas RNA only is single-stranded
- DNA is a deoxyribose sugar whereas RNA is a ribose sugar
- DNA bases are A,T,C, G and RNA is A,U,C,G
- DNA is long whereas RNA is shorter
9
Q
Why is DNA stable?
A
- phosphodiester bonds creating a sugar-phosphate backbone
- There are three hydrogen bonds between cytosine and guanine so the more c-g bonds the more stable
10
Q
What bases are purines and pyrimidines?
A
Cytosine and Thymine are pyrimidines whereas Adenine and Guanine are purines
11
Q
How do the properties of DNA help its function?
A
- large, contains a lot of information
- stable so it can last many generations
