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In this chapter of IBDP Biology, we will learn about the structure and function of DNA.
Structure of Nucleic Acid
- The monomer units in nucleic acids are called nucleotides.
- They consist of a pentose sugar (deoxyribose/ribose) a phosphate group and a nitrogenous base that is either a pyrimidine or a purine.
- These three components are joined in condensation reactions by covalent bonds.
Nucleotide derivatives
- When it comes to IBDP Biology, ATP and ADP are nucleotide derivatives and are often present in co-enzymes such as NADP – nicotinamide adenine dinucleotide phosphate which is used in photosynthesis.
Structure of DNA
- DNA is made of two polynucleotide strands, antiparallel to each other.
- The monomers in DNA include deoxyribose sugar, a phosphate group and the bases cytosine, thymine, adenine and guanine.
- The monomers are bonded by covalent phosphodiester bonds.
- The bases are bonded with hydrogen bonds in complementary base pairing. These hydrogen bonds are weak but together are stronger as there is a large number of them.
Functions of DNA
- When it comes to IBDP Biology, DNA is a macromolecule and is very long to store all the information.
- It stores genetic information and hereditary material in the sequence of its bases.
- In eukaryotes, DNA is stored in the nucleus and is wound around histone proteins to form chromosomes. Each chromosome is one molecule of DNA. There is also a loop inside mitochondria and chloroplasts.
- n prokaryotes, DNA is in a loop floating free within the cytoplasm and is not wound around histone proteins. It is therefore naked.
This is the end of this topic