What do Genes Look Like?
Chapter 7, section 1 notes
What we know: Genes are located on
chromosomes and chromosomes are
made of DNA.
• DNA
- Hereditary material that controls the
activity of a cell.
- Contains information to make new cells.
- Provides instructions for making protein.
DNA serves two main
functions
• To supply complex
instructions for cell
processes and for
building cell
structures.
• To be able to be
copied each time a
cell divides.
How can something so small hold
the keys for making and directing
living organisms?
Let’s take a look inside…
Nucleotides- the subunits of
DNA
• 4 nucleotides make
up DNA
1. Adenine
2. Thymine
3. Guanine
4. Cytosine
3 different types of materials
make up a nucleotide
• 1. Sugar
• 2. Phosphate
3. Base
The People involved
• Erwin ChargaffChargaff’s Rule- A = T
and G = C
• Mnemonic Device
• Atoms are Tiny
(adenine pairs with
thymine)
• Candy is Great
(cytosine pairs with
guanine)
Rosalind Franklin
• She used x-ray
diffraction to capture
an image of a DNA
molecule that
suggested that DNA
has a spiral shape.
James Watson and Francis Crick
• Took the information
from Wilkins and
Franklin and
concluded that DNA
resembles a twisted
ladder shape known
as a double helix.
They used this
model to predict
how DNA is copied.
Notes on your own…
• DNA’s Double Structure (pg. 210)
• DNA Replication (pg. 210)
– How Copies Are Made (pg. 211)
– When Copies Are Made (pg. 211)
For each sub heading write down three or four
important facts. Also draw a sketch to model how
DNA is replicated.