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Chapter 11 - Coggle Diagram
Chapter 11
Features of DNA
Double stranded
Antiparallel
Right-handed helix
Sugar-phosphate backbone
Specific base-pairing
Bases on the inside
Stabilized by H-bonding
~10 nts per helical turn
The main players
DNA helicase
DNA topoisomerase
Single-strand binding proteins
DNA polymerase
Requires a primer
only works 5’ to 3’
Deoxynucleoside triphosphates
DNA primase
DNA Structure
Nucleotides
building blocks of DNA
Strand
linear polymer strand of DNA
Double helix
two strands of DNA
Chromosomes
DNA associated with an array of different proteins into a complex structure
Genome
complement of genetic material in an organism
DNA
Phosphate group
Pentose sugar
Nitrogenous base
Purines
(double ring)
Pyrimidines
(single ring)
Strands
Nucleotides are covalently bonded
phosphate group links two sugars
Backbone
phosphates and sugars
Base-pairing
amount of adenine (A) = amount of thymine (T)
amount of cytosine (C) = amount of guanine (G)
A with T and G with C
DNA Replication
Semiconservative
1 parental strand and daughter strand.
Conservative
1 double helix with both parental strands and the other with 2 new daughter strands.
Dispersive
new DNA are interspersed with the parental DNA
The mechanism accuracy
Hydrogen bonding
DNA polymerase is unlikely to form bonds if pairs mismatched
DNA polymerase can proofread to remove mismatched pairs
Telomeres
nucleotide sequences repeated at the ends of chromosomes
at 3’ does not have a complementary strand
Telomerase enzyme attaches many copies of DNA repeat sequence to the ends of chromosomes
levels of DNA compaction
DNA wrapping
30-nm fiber
Radial loop domains
numbering system
Base attached to 1’ carbon
Phosphate attached to 5’
Mechanism of DNA Replication
Bacteria
single origin of replication
Eukaryotes
multiple origins of replication
Structure of Eukaryotic Chromosomes
may be hundreds of millions of base pairs
composed of chromatin