Download 12 1 DNA

Chapter 12:
Molecular Genetics
• DNA structure
• Protein synthesis
• DNA Replication
DNA: The Genetic Material
Section 1 – p. 329
Warm-up:
1. DNA is what kind of macromolecule?
A. Protein
B. Lipid
C. Carbohydrate
D. Nucleic acid
2. The macromolecule, DNA, is made up of which
kind of monomers?
A. Amino acids
B. Fatty acids
C. Monosaccharides
D. Nucleotides
Essential Questions
1. What is DNA?
2. How can we describe Chargaff’s base
pairing rules?
3. Compare the structure of a eukaryotic
chromosome with prokaryote DNA.
4. How are genes, chromosomes, and DNA
related?
The “OLD” People of DNA
1.Fredrick Griffith
2.Oswald Avery
3.Hershey and
Chase
4.Erwin Chargaff
5.Watson and
Crick
Fredrick Griffith-1928
 In 1928, British scientist Fredrick Griffith was
trying to learn how certain types of bacteria caused
pneumonia.
 He isolated two different strains of pneumonia
bacteria from mice and grew them in his lab.
 Performed the first major experiment that led
to the discovery of DNA as the genetic
material
 Transformation
Griffith determined that bacteria could pass
genetic information from one to another.
 Griffith called this process transformation because
one strain of bacteria (the harmless strain) had
changed permanently into another (the disease
causing strain).
But what was
the
transforming
factor?
Oswald Avery-1944
 Oswald Avery repeated Griffith’s work to
determine which molecule was most
important for transformation.
 Identified the molecule that transformed the
R strain of bacteria into the S strain
 Concluded that when the S cells were killed,
DNA was released
 R bacteria incorporated this DNA into their
cells and changed into S cells.
Discovered that DNA was the
“transforming factor”.
Hershey and Chase-1952
 Alfred Hershey and Martha Chase studied viruses—
nonliving particles smaller than a cell that can
infect living organisms.
 If Hershey and Chase could determine which part
of the virus entered an infected cell, they would
learn whether genes were made of protein or DNA
 Concluded that the viral DNA was injected into the
cell and provided the genetic information needed
to produce new viruses
Provided definitive evidence
that DNA is the source of
genetic material.
So Griffith, Avery, Hershey and Chase
all helped discover DNA and the
importance that it plays in
transmitting genes.
But what is DNA???
What is it made of???
What does it look like??????
Warm-up
• A nucleotide is made up of three parts.
What are they? (Use your book if you
like.)
What is DNA?
1. A genetic code
2. A molecule made of
subunits called
nucleotides
3. A complex molecule
that is arranged as a
double helix.
NUCLEOTIDES
are the smallest units
(monomers) of DNA that
include:
Phosphate group
5-Carbon sugar
Nitrogen base
NUCLEOTIDES
the smallest subunit of DNA
Two Kinds of bases in DNA
 Pyrimidines are single ring bases.
Thymine & Cytosine
Memory trick “Y” are you single?
 Purines are double ring bases.
Adenine & Guanine
A
G
C
T
Erwin Chargaff Analyzed the amounts of A, C, T, and G in
DNA; Discovered A=T & C=G
The Shape of DNA is a Double
Helix
 DNA often is compared
to a twisted ladder.
 Rails of the ladder are
represented by the
alternating deoxyribose
and phosphate.
 The pairs of bases
(cytosine–guanine or
thymine–adenine) form
the steps.
Watson and Crick
 Built a model of the double helix that
conformed to the others’ research
1. two outside strands consist of alternating
deoxyribose and phosphate molecules
2. cytosine and guanine bases pair to each
other by three hydrogen bonds
3. thymine and adenine bases pair to each
other by two hydrogen bonds
Watson and Crick
 Suggested the structure for DNA and
hypothesized a method of replication
Refer to the DNA handout
1. Locate the Phosphate groups. Label
each one “P” and color them
orange.
2. Locate the deoxyribose sugars and
label them. Color all sugars blue.
3. Locate the nitrogen bases and label.
4. Label the hydrogen bonds.
DNA Structure Activity
1. Locate the nitrogen bases
2. Label Adenine and color it purple.
3. Label Thymine and color it yellow.
4. Label Cytosine and color it red.
5. Label Guanine and color it green.
4 Nitrogen Bases
Purines are
Pyrimidines are
larger bases
smaller bases
Adenine
Thymine
Guanine
Cytosine
CHARGAFF’S BASE
PAIRING RULES
A binds with T
G binds with C
Hydrogen
Bonds
Fig. 4. Adenine-Thymine
base pair with two
hydrogen bounds.
C = Carbon = gray
Fig. 5. Guanine-Cytosine
base pair with three
hydrogen bounds
N = Nitrogen = blue
O = Oxygen = red
3-D Animation
of DNA
http://www.umass.edu/molvis/tutorials/dna/dnapairs.htm
Stop & Review
1. What is the smallest subunit of DNA?
2. List 3 parts to #1?
3. What are the side chains of DNA made
of?
4. What are the “steps” of DNA made of?
5. What are the base pairing rules of
DNA?
6. Describe the structure of DNA in 2
words.
ANSWERS
1.Nucleotide
2.Sugar, phosphate, and a
nitrogen base
3.Sugar and phosphate
4.Nitrogen base
5.A=T, C=G
6.Double Helix
Comparing eukaryote & prokaryote
DNA
PROKARYOTE
EUKARYOTE
Circular
Linear
How are genes, chromosomes,
and DNA related?
Genes are
portions of
DNA that are
tightly packed
into
chromosomes
and code for
the
manufacture of
proteins.
How are genes, chromosomes
and DNA related?
Think of
chromosomes
as socks and
genes as stripes
on the socks.
Place in order from smallest to
largest.
Gene
DNA
Chromosomes
Vocabulary
Clarification
CHROMATIN
CHROMOSOME
Have Your DNA & eat it too!
1.Collect materials
2.Follow instructions
*A (green) pairs with
T (pink)
*C (yellow) pairs with
G (orange)
Warm-up
1.
Is DNA double stranded or single
stranded?
2.If you are given the DNA sequence
ATCCGTTAC, what would be the
sequence of the complementary
strand?