15 - DNA structure and replication Flashcards
DNA backbone
is the structural framework of the DNA molecule. Consists of sugars and phosphates
5’ end
one end of the molecule where a phosphate is ATTACHED to the FIFTH carbon atom of the sugar molecule
3’ end
end of a DNA or RNA strand where the THIRD carbon atom of sugar molecule has a HYDROXYL group (OH) attached
Pyrimidines
1/2 types of nitrogenous bases. have a SINGLE ring structure. CYTOSINE (C) and THYMINE (T)
Purines
1/2 types of nitrogenous bases. They have DOUBLE ring structure. Contain ADENINE (A) and GUANINE (G)
Thymine
is one of the four nitrogenous bases found in DNA. PYRIMIDINE
Guanine
one of four nitrogenous bases found in DNA and RNA. It is PURINE base – DOUBLE ring structure.
Cytosine
One of four nitrogenous bases found in DNA and RNA. It is a PYRIMIDINE base—SINGLE ring structure
Adenine
One of four nitrogenous bases in DNA and RNA. It is a PURINE base—DOUBLE ring structure
Antiparellel nature
refers to the orientation of the two strands in the DNA double helix. The strands run in OPPOSITE directions: ONE strand goes from the 5’ end to the 3’ end, while the OTHER goes from the 3’ end to the 5’ end.
Helicase
enzymes that untwist the double helix at the replication forks, separating the two parental strands and making them available as template strands
DNA polymerase
is an enzyme that helps build new DNA strands during cell division. It adds nucleotides to the growing strand
Semiconservative model
predicts that when a double helix replicates, each of the two daughter molecules will have one old strand from the parental molecule, and one newly made strand
Deletion
Occurs when a chromosomal fragment is lost
Inversion
when a chromosomal fragment may reattach to the original chromosome but in the reverse orientation
