DNA
Chapter 13
DNA=Deoxyribonucleic Acid
-nucleic acid macromolecule group
-makes up chromosomes
-a section of DNA = gene
DNA Construction:
-composed of 4 types of nucleotides
--Who was Chargaff?
-nucleotides linked into 2 strands by
phosphodiester bonds
-the 2 strands are held to each other by
hydrogen bonds
-entire structure then spirally twists =
helical shape or Double Helix
-Who was Watson & Crick?
Nucleotide composed of:
1. Phosphate group (P-group)
2. 5-carbon sugar ring (Ribose=pentose)
3. Nitrogen-base
4 types of bases:
2 Purines
1. Adenine A
2. Guanine G
2 Pyrimidines
3. Thymine T
4. Cytosine C
-only one base per nucleotide
-DNA composed of 4 types of nucleotides
known as A, G, C, or T nucleotides.
-nucleotides are linked into two strands by phosphodiester bonds.
-each DNA strand has a 3' end & a 5' end
-the two strands orient opposite each other.
Chargaff’s Rule:
-A nucleotides of one strand H-bond with T
nucleotides in the opposite strand
-G nucleotides of one strand H-bond with C
nucleotides in the opposite strand
-A bonds with T
-G bonds with C
-This is termed complimentary base pairing.
DNA Replication
From one current DNA molecule, two new molecules are formed
-parental DNA=
template=
-daughter DNA=
-Semiconservative Replication=
Replication Steps:
1. Unwinding
-separate parental strands.
-Helicase=
2. Complimentary Base-Pairing
3. Joining
-Steps 2 and 3 conducted by
-DNA Polymerase=
-reading direction=
-Leading strand=
-Lagging strand=
-Okazaki fragments=
Prokaryotic Replication=
Eukaryotic Replication=
-replication fork=
-replication bubble=
Replication errors=
-mutation=
-Proofreading/repair=