Chapter 16 Flashcards
4 DNA criteria
Information storage, replication, transmission, variation
Information storage
DNA must contain the information necessary to construct an entire organism
Replication
Due to its transmission through generations, DNA must be copied
Transmission
Information must be passed from cell-to-cell and from parent offspring
Variation
DNA must contain variation that accounts for physical differences within each species
DNA sugar
Deoxyribose
RNA sugar
Ribose
What kind of bond hold the stands of the helix together?
Hydrogen bonds
Name of the initiation point
Origin of replication
What does DNA helicase do?
Enzyme splits the hydrogen bonds between 2 strands
What do single strand binding proteins do?
Keep the strands from repairing
What does topoisomerase do?
Helps relieve the strain as the untwisting causes tighter twisting ahead
What does DNA polymerase III do?
Synthesizes DNA replication ; can’t initiate process without short DNA primer
What synthesizes the primer?
RNA primase (only works 5’-3’)
What does DNA polymerase do?
Start the new DNA strands from the 3’ end of the RNA primer
What does dATP do?
Supplies adenine to DNA and is similar to the ATP of energy metabolism
Which way does DNA polymerase III add nucleotides?
5’-3’
Leading strand
Continuous ; 5’-3’ ; 1 primer
Lagging strand
Discontinuous ; 5’-3’ ; Okazaki fragments ; several primers
What does DNA polymerase I do?
Replaces RNA with DNA
What does DNA ligase do?
Forms a bond between the newest DNA and the DNA fragment 1
What is a telomere?
The protective ends of chromosomes that consist of repetitive sequences ; don’t shorten them
Proofreading
Enzymes like nucleuses remove the wrong nucleotides and DNA polymerase fills in the gaps
What happens in nucleotide excision?
Nuclear enzyme cuts the damaged DNA and removes it, then DNA polymerase fills the missing nucleotides, finally DNA ligase seals it making the strand complete
