The Structure and Function of DNA
CHAPTER 10
•The Hereditary Material: DNA or Protein?
• DNA and RNA Structure
• Deoxy- and ribonucleotides
• Double helical structure of DNA
• 5' and 3' ends
• DNA Replication
• DNA polymerase
• Semiconservative replication
•From Gene to Protein
• Transcription and Translation
Facts About Hereditary Material
DNA: Structure and Replication
• DNA
– Was known to be a chemical in cells by the end of
the nineteenth century.
– Has the capacity to store genetic information.
– Can be copied and passed from generation to
generation.
DNA and RNA Structure
• DNA and RNA are nucleic acids.
– They consist of chemical units called nucleotides.
– The nucleotides are joined by a sugar-phosphate
backbone.
Hershey-Chase Experiment
Phage T2 Reproductive Cycle
DNA and RNA Structure
DNA is a Double-Stranded Chain of Nucleotides
DNA Chains Are Held Together By Nitrogenous Base H-Bonds
Watson and Crick’s Discovery of the Double Helix
• James Watson and Francis Crick determined that
DNA is a double helix in 1953.
DNA Replication
• When a cell or whole organism reproduces, a
complete set of genetic instructions must pass from
one generation to the next
• DNA Replication occurs in S phase of Interphase
• One DNA double-helix becomes two identical
double helices: sister chromatids
S
G1
G2
M
DNA
Replication
Each Chromosome “Unzips” as a New Complementary
Strand is Synthesized Along Side the Old One
Replication
Figure 10.6
• DNA can be
damaged by
ultraviolet light.
– The enzymes and
proteins involved
in replication can
repair the
damage.
How Do Chromosomes Carry Information?
A karyotype made from chromosomes of a single cell
Central Dogma of Biology: How Shape and Form Are Dictated By DNA Genes
Genotype:
The genes
carried in a
cell for a
particular
trait
Phenotype:
The physical
expression of
genes for a
particular trait
A segment of
DNA (gene)
carries
specific coded
instructions
for the making
of a single
proteins.