Intro To Molecular Biology 1 Flashcards
Difference between RNA and DNA:
RNA has extra component on sugar (oxygen and hydrogen)
What linkage is present in the DNA and RNA polymers?
5-3 Phosphodiester Linkage
Phosphorus between oxygens
What are purines?
2 rings
Adenine and Guadine
What are pyramidines?
Single ring
Thymine and Cytoseine
Bases in RNA:
Uracil instead of Thymine
How is uracil different to thymine?
Uracil misses the methyl group
Strands in DNA:
Two complementary strands of DNA bind together - held by hydrogen bonds
Hydrogen bonds between bases:
A-T = 2 H bonds
C-G = 3 H bonds (more energy to break)
Structure of Double Helix:
Sugar-phosphate backbone
Bases on inside
Major and minor groove formed
Properties of DNA strands in double helix:
Polar
Antiparallel
How can chromosomes be distinguished?
Size
G-banding
How is DNA organised?
Into chromosomes
What happens to chromosomes when cells divide?
Condense
What is a nucleosome?
147 base pairs of DNA
Wrapped around histone proteins
1.7 left-handed turns
What are histone proteins?
Positively charged
Long N-termini
How are histone proteins arranged in nucleosome?
Histone proteins in centre but with amino-terminal tails protruding
DNA strands on outside
What does histone H1 help form?
30nm fibre
Fits inside groove to allow DNA to keep folding and staying in place around core histones
How is DNA packaged?
As ‘beads on string’
Into 30nm fibre and further condensed
Does chromosome compaction vary?
During cell cycle
Why do chromosomes need to be remodelled?
Chromatin can decondense to allow protein access
What’s included in repetitive DNA?
Interspersed repeats - repeat sequences are dispersed throughout genome
Tandem repeats - short series of bases repeated multiple times after one another (satellites, minisatellites and microsatellites)
What is repetive DNA important in?
Forensics
What is mitochondrial DNA like?
Circular
Maternally inherited - implications for disease
Used for forensics
