Introduction To DNA Flashcards
Heterochromatin
Dark part of nucleus
Genes not expressed
DNA in solenoid
Euchromatin
Light part in nucleus
Genes expressed
Beads on a string
DNA packaging
DNA wound around histone core of nucleosome
Joined together by linker DNA of nucleosome
Beads on a string then made into a solenoid
Genes
Carry code for proteins
Have chromosomal location (stretch of gene)
Have about 25,000 genes
Genome
Entries DNA sequence 24 chromosomes (22 plus 2 sex chromosomes)
DNA structure - Nucleotide
Base
Ribose sugar
Phosphate
DNA structure - Nucleoside
Base
Ribose sugar
Purines
2 rings
Adenine and guanine
Pyrimidine
1 ring
Cytosine
Thymine
Polynucleotide
Nucleotides joined by phosphodiester bond
5’ (P) to 3’ (OH)
Base pairing
Amine group of base of one nucleotide forms H bonds with C=O of base of opposite nucleotide
Base pairing
G-C has 3 H bonds
A-T has 2 H bonds
A-U has 2 H bonds
Secondary structure
Strands are complementary and anti-parallel
Right handed double helix
Cell cycle
Cell division
G1 - cell content replication
S - DNA replication
G2 - double check and repair
DNA replication
Semi-conservative model Catalysed by DNA polymerase 2 phosphates are released for each nucleotide added Driven by pyrophosphate hydrolysis Chain growth 5’ to 3’