DNA structure and function Flashcards
what does DNA stand for ?
Deoxyribonucleic acid
what does DNA code for ?
DNA codes for the sequence of amino acids in the primary structure of a protein
what does the coding of the primary structure determine ?
it determines the final 3D structure and function of a protein
what is it essential that cells contain ?
it is essential that cells contain a copy of the genetic code and that it can be passed onto new cells without being damaged
What is the DNA polymer ?
a double helix
what is the name of the monomer that makes up DNA ?
a nucleotide
what does the nucleotide consist of ?
- deoxyribose ( pentose sugar)
- a nitrogenous base
- 1 phosphate group
what are the possible nitrogenous bases ?
- guanine
- cytosine
- thymine
- adenine
draw the structure of a nucleotide
consolidate notes
what is the name of the nucleotide polymer ?
polynucleotide
what kind of reaction is the polynucleotide created by ?
via a condensation reaction
formation of polynucleotides
- between which molecules does the condensation reaction occur ?
between the deoxyribose sugar and the phosphate group
what kind of bond is formed between the deoxyribose sugar and the phosphate group in the formation of polynucleotides ?
a phosphodiester covalent bond
what are the properties of phosphodiester bonds and what do they ensure ?
- phosphodiester bonds are strong covalent bonds
- therefore ensure that the genetic code is not broken down as the nucleotides are held strongly together
what happens in a condensation reaction ?
a water molecule is removed to form a bond and join 2 molecules together
sometimes the polynucleotide is described to have a… ?
sugar- phosphate backbone
what does the sugar phosphate backbone refer to ?
its describing the strong covalent bonds between the sugar and phosphate groups that hold the polymer together
what do DNA polymers occur in ? How many monomers is the polymer made up of ?
DNA polymers occur in pairs
How are the 2 DNA monomers / nucleotides joined together ?
they are joined together by hydrogen bonds between the complimentary base pairs
what does the joining of 2 nucleotides with hydrogen bonds create ?
it creates the double helix structure as the 2 chains twist
what are the complimentary base pairs ?
- cytosine and guanine
- adenine and thymine
how many hydrogen bonds are there in between guanine and cytosine ?
3 hydrogen bonds
how many hydrogen bonds are there between adenine and thymine ?
2 hydrogen bonds
why is the complimentary base pairing important ?
it is important to help maintain the order of the genetic code when DNA replicates
