Lectures 16-18 - Gene And Chromosome Structure Flashcards
(20 cards)
What are nucleic acids composed of?
Nucleotides
DNA is composed of
Nitrogen containing bases (A,T,G,C) and U, sugars, phosphate
Which are purine?
A and G
Which are pyryimidine?
C, T, U
How are nucleotides joined?
Phosphodiester bond
What does the phosphodiester bond link?
C3 and C5 to another sugar
How many h bonds between T and A
2
How many H bonds between C and G?
3
Two strands of dna and polarity?
Opposite polarity
Techniques for dna and rna analysis?
Molecular hybridization
Gel electrophoresis
Restriction enzymes and cloning
PCR
Next generation sequencing
PCR?
Forward primer: Anneals to the bottom strand and has the same sequence as the top strand
Reverse primer: anneals to the top strand and has the same sequence as the bottom strand
What is super coiling?
DNA double helix curls again
How does dna become super coiled?
Single strand nick in dna allows it to form figure 8 and supercoil
Genomes comparison?
Eukaryotes have large genomes
What is chromatin?
DNA+histones+protein
What are the three levels of dna packaging?
Nucleosomes
30 nm chromatin fibre
Inter-phase chromosomes
First level of dna packaging?
DNA wraps around nucleosomes, 1 3/4 times and are linked by linker dna, it is 11nm in width
What are nucleosomes consisting of?
8 histones
What is the second level of packaging?
Nucleosomes with linker dna folds into 30 nm diameter chromatin fibre
What is the third level of packaging?
30 nm fibre attaches to chromosome scaffold which folds and twists, it is 300 nm in diameter
