Chapter 1 - DNA structure Flashcards
What is the monomer of the DNA?
Nucleotide
What are the three components a Nucleotide is made up of?
Phosphate group, Deoxyribose sugar and Nitrogenous base
What are the two groups of Nitrogenous bases?
Purines and Pyrimidines
Which DNA bases are purines? and what is the structure?
Adenine and Guanine
Made up of two rings fused together
Which DNA bases are pyrimidines? and what is the structure?
Thymine and Cytosine
Single rings
How are Nucleotides joined together?
Condensation polymerisation
How is the sugar-phosphate backbone formed?
Phosphodiester bonds form between oxygen ion of phosphate group and OH group on 3’ carbon of sugar molecule
How many sugar-phosphate bonds do DNA have?
2
How do nitrogen bases bond together?
By hydrogen bonds
Describe the type of hydrogen bond between each nitrogen base
A and T = double hydrogen bonds
C and G = triple hydrogen bonds
Explain the Chargaff’s rule
Each nitrogen bae only pairs with one other purine with pyrimidine
A and T, C and G
Describe the overall structure of a DNA
- Double stranded molecule
- Sugar phosphate backbones with nitrogen bases attached
- Two strands run antiparallel
One runs 5’ to 3’ and the other runs 3’ to 5’ - Strong intramolecular forces between bases to twist
How does a DNA fit inside the nucleus of a Eukaryotic cell?
Double helix DNA is twisted and coiled around Histones (protein) to prevent it from getting tangled
What is a DNA-Histone complex called?
Chromatin fibres
What occurs when the cell wants to divide?
It coils even more (super coiling) and appears shorter and thicker to become a chromosome structure
