2.1.3 Nucleotides and Nucleic acids - Nucleotides Flashcards
What are the components that make up a nucleotide?
- a phosphate group, -PO4 (2- charge)
- a pentose monosaccharide sugar
- a nitrogenous base
How are nucleotides linked together? and how do they break apart?
Linked together by condensation reactions to form a polymer called a polynucleotide.
Phosphodiester bonds are broken by hydrolysis.
What are phosphodiester bonds?
the phosphate group at the fifth carbon of the pentose sugar (‘5) of one nucleotide forms a covalent bond with the hydroxyl (-OH) group at the third carbon (‘3) of the pentose sugar of an adjacent nucleotide.
These BONDS are known as PHOSPHODIESTER BONDS.
What is the difference between DNA and RNA
DNA:
- contains deoxyribose sugar
- double helix
- contains Thymine (T)
RNA:
- contains ribose sugar
- single-stranded (can be transported through the nuclear envelope pores to ribosomes)
- contains Uracil (U) instead of Thymine (T)
What are Pyrimidines?
the smaller bases, which contain a single carbon ring structure.
Thymine (T) and Cytosine (C)
a quick way to remember is TutanKhamon was buried in a pyramid
What are Purines?
the larger bases, which contain double carbon ring structure
Adenine (A) and Guanine (G)
What bonds keep together the two strands of a double helix?
hydrogen bonds
Why is DNA (e.g. its double helix) referred to as antiparallel?
each strand has a phosphate group (‘5) at one end and a hydroxyl group (‘3) at the other end. The two parallel strands are arranged so that they run in opposite directions.
Complementary base pairings?
In DNA:
A-T, C - G
In RNA:
A-U, C-G
Why do bases only pair to those particular bases (why are their complementary base pairings)?
Adenine (A) and Thymine (T) are both able to form two hydrogen bonds.
Cytosine (C) and Guanine (G) form three bonds.
