2. Intro: The role of nucleic acids.
DNA and RNA are known as the nucleic acids.
They are acidic molecules
DNA is responsible for storing information of the
genetic characteristics of an organisms
RNA enables the information stored in DNA to be
expressed
In carrying out its functions, DNA needs to have:
i. Stable molecule
ii. Contain some ‘code’
iii. Must be able to replicate
3. B 8.1: Describe the structure of nucleotides and their
condensation polymers (nucleic acids or
polynucleotide).
DNA & RNA = polymers
Built from monomers known as nucleotides, so it is
polynucleotide
4. A. Nucleotides are the building blocks of nucleic
acids
Nucleotides is made up of 3 components:
i. Pentose sugar: C5H10O5 (DNA = deoxyribose,
RNA= ribose)
8. Adenine, guanine, cytosine = found in DNA &
RNA
Thymine = exclusively in DNA
Uracil = exclusively in RNA
Ribonucleotides are found in RNA: contain
ribose sugar and either A, G, C or U.
Deoxyribonucleotides are found in DNA:
deoxyribose sugar and either A, G, C or T.
9. B. Nucleotides condense to form polynuleotides
Nucleotides link together in condensation
reaction involving the phosphate at the 5’
position of one nucleotide and the –OH group
at the 3’ position of the next nucleotide.
11. C. DNA is a double helix of two polynucleotides
2 polynucleotide strand are coiled around the same axis
forming a double helix with sugar-phosphate backbone on the
outside and the nitrogeneous bases on the inside.
12.
13. 10 nucleotides = one complete turn of the
helix with length of 3.4 nm
The 2 polynucleotides strands are anti-parallel
(3’ 5’ and 5’ 3’)
Base pairing: A=T , G C
14. D. RNA is a single-stranded polynucleotide molecules
RNA differs from DNA:
- Ribose sugar instead of
deoxyribose
- The base uracil instead of
thymine
- A single stranded
structure
- Less stable than DNA
- Short-lived in the cells
- RNA is able to cross the
nuclear membrane
15. • 3 different RNA exist in
human:
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Ribosomal RNA (rRNA)
*RNA polynucleotide is
able to carries
information in its
sequence of bases