Download FINDING DNA

FINDING DNA
The Race is on…
APRIL 25
The day commemorates the
completion of the Human
Genome Project (complete
mapping of genes of humans)
in April 2003, and the
discovery of DNA's double
helix.
Finding the A T C G order of an
average human and what it
codes for
Chromosome
#9
Was the genetic material
protein or DNA?
• Chapt. 9 Mendel (peas) did not
know about DNA.
•
•
Worksheet links
Bozeman Biology: DNA and RNA Part I Bozeman Biology: DNA and RNA Part II
The Race to Find DNA
Youtubes
• Finding the Structure of DNA (9:15)
• The Secret of Photo 51 (55 minutes)
• Watch Friday, April 24
• The story of Rosalind Franklin (2:24) -
Get out CHART:
DNA Race Scientists
•
Frederick Griffith
• A medical officer was
trying to find a
vaccine against
pneumococcus
Rough and Smooth Pneumococcus
benign
No capsule
virulent
Thick capsule
Griffith 1920’s
• Streptococcus pneumoniae used
to show a “transforming factor”
• bacteria transformation youtube (23 seconds)
Griffith’s Conclusion
• Some material* in the heat-killed S strain of
pneumococcus that was responsible for
“transforming” the R-strain into a lethal form
• transformation = passing the
inheritance factor* from one
organism to another
• *THIS TRANSFORMING FACTOR WAS LATER
FOUND TO BE DNA
Nerd Cartoons
Oswald Avery 1944
He had reported that DNA, not
protein (which was believed at the time),
was the hereditary substance (transforming
material).
Studied
medical
research
Oswald Avery 1940’s
Avery’s Conclusion
• EXPERIMENT: Separated the DNA, RNA,
protein from S-strain pneumococcus
• AVERY PROVED THAT DNA WAS THE
TRANSFORMING MATERIAL
Alfred Hershey and Margaret
Chase 1953
• Showed that the hereditary
material in bacteriophage viruses
is DNA.
DNA in
water
• Hershey-Chase Bacteriophages Youtube (1:49)
• McGraw-Hill Hershey-Chase Experiment
Radioactive P32 in DNA
Radioactive S35 in protein
Hershey-Chase
• CONCLUSION –
• DNA is genetic material
32
because ( P) nucleic acid
not (35S) protein guides
viral replication
Bacteriophages (“bacteria-eaters”)get handout
Virus Examples
• Cold Virus
HIV Virus
Bird Flu
Virus
Ebola Virus
Herpes Virus
Bacteriophage Structure
(Capsid)
D
A
B
E
C
Virus: Are they Alive?
• Viruses can only replicate in a
living host.
• "Viruses straddle the definition of life. Viruses
contain some of the structures and exhibit some
of the activities that are common to organic life,
but they are missing many of the others.”
• Dr. Mark Young of MSU youtube (4:00)
• Are virusees alive? (2:57)
Bacteriophage Virus Lytic Infection
1.Attach to host (E. coli)
2. Insert DNA
3. Make DNA parts
4.assemble DNA parts
5. Lyse (burst)-kills
EXAMPLES:
Cold
Flu
Lysogenic Infection
• 1. Virus lands on host.
• 2. Virus injects DNA into host.
• 3. Virus DNA attaches to host DNA =
prophage.
• 4. Virus Prophage will become lytic when
conditions are favorable (you are sick, tired).
• lysogenic infection youtube (1:25)
• Mr. W's "I'm a virus“ (4:02)
PROPHAGE:
viral gene inserted and
integrated into the
circular bacterial DNA
chromosome …forever
Lysogenic:
Will replicate with the host
cell…forever.
Lysogenic Cycle Animation
• Animation Quiz 2 - Lamda Phage
Replication Cycle
• EXAMPLES:
HERPES
HIV
• CHICKEN POX
Identifying Bacteria: Shapes
• Cocci- spherical
• Bacilli – rod
• Spirilla – spiral
Identifying bacteria: Groupings
• Diplo: Two
Staphylo
: cluster
Sarcina: 8
Tetrad: 4
Strepto:chain
Bacterial Shapes and
Arrangements
• Gram +
and Gram –
Tests +/endospore
Sugar
Test
Aerobic/anaerobic
test
Keep a
checklist
of results
Who am I?
Who am I?
streptobacillus
What is the structure of DNA?
• It is a nucleic acid
(macromolecule)
• Polynucleotide
(polymer) = Made of
long chains of
Nucleotides
(monomers)
DNA Nucleotide
“monomer of nucleic acid”
Phosphate
Group
O
O=P-O
O
5
CH2
O
N
C1
C4
Sugar
(deoxyribose)
C3
C2
Nitrogenous base
(A, G, C, or T)
DNA Structure
Macromolecule:
Nucleic
Acid
• POLYMER:
• MONOMER:
NUCLEOTIDE
POLYNUCLEOTIDE
Ladder sides
“rungs”
A Nucleotide
• MADE OF:
–Sugar
–Phosphate
–Base
• Deoxyribose sugar
• PO4
• 4 kinds of bases:
• (A) (G) (T) (C)
(names on next slide)
4 Types of Base Pairs
• A = adenine
• T = thymine
• C = cytosine
• G = guanine
• NOW SING THE DNA SONG (next slide)
DNA Song (to the tune of “row,
Row, Row Your Boat”)
•
•
•
•
•
We love DNA
Made of Nucleotides
Sugar, phosphate, and a base
• Row
Bonded down one side
Your
Adenine with thymine make a
Boat
lovely pair
Karaoke
• Cytosine without guanine would
feel very bare
Nitrogenous Bases
• PURINES -2 rings
1. Adenine (A)
AG = silver
2. Guanine (G)
• PYRIMIDINES -1 ring
3. Thymine (T)
4. Cytosine (C)
CUT
A or G
T or C
DNA
•Deoxyribonucleic Acid
Purine =
AG
Pyrimidine
= CUT
• Covalent bonds between a phosphate
and two sugar molecules
(phosphodiester).
• H-bonds between
complimentary bases
DNA Double Helix
“Rungs of ladder”
Nitrogenous
Base (A,T,G or C)
“Legs of ladder”
Phosphate &
Sugar Backbone
DNA backbone
• Sugar
• Phosphate
DNA Structure
• Rungs of the Ladder:
– Various orders of
A, T, C, G
• Backbone:
– Sugar and phosphates
– Alternate
DNA Double Helix
5
O
3
3
O
P
5
O
C
C
G
G
1
P
5
3
2
4
4
2
3
1
P
T
5
A
P
3
O
O
P
5
O
3
5
P
What’s RNA?
• Ribonucleic
Acid
–Three types:
–mRNA
–tRNA
–rRNA
Comparing DNA and RNA
“two kinds of nucleic acids”
• DNA
• RNA
• Double stranded
• Sugar =
deoxyribose
• Bases: A-T, C-G
• Found only in
nucleus
• Can repair itself
•
•
•
•
•
Single stranded
Sugar = ribose
Bases: A-U, C-G
U=uracil
Found in and out
of the nucleus
• Cannot repair itself
RNA
DNA
Pretty Similar
• Uracil
• Thymine
DNA
- Contains Thymine
- Contains
deoxyribose sugar
- Double stranded
molecule
- Found only in
nucleus
Both
RNA
- Made of
nucleotides
- Single stranded
molecule
- Contain adenine,
guanine and
cytosine
- Contains uracil
- Contains ribose
sugar
- Found in nucleus
and cytoplasm
• Bozeman Biology DNA and RNA Part 1
• Griffith, Avery, Hershey and Chase,
Watson and Crick, pro and eukaryotic
chromos
• Bozeman Biology DNA and RNA part 2
• DNA replication
• Transformation
• Protein synthesis
•
•
•
•
•
•
•
Relative Proportions (%)
of Bases in DNA Organisms
A
T G C
Human
30.9 29.4 19.9
Chicken
28.8 29.2 20.5
Grasshopper 29.3 29.3 20.5
Sea Urchin 32.8 32.1 17.7
Wheat
27.3 27.1 22.7
Yeast
31.3 32.9 18.7
E. coli
24.7
23.6 26.0
19.8
21.5
20.7
17.3
22.8
17.1
25.7
Question:
• If there is 30% Adenine, how much
Cytosine is present?
• HINT: A –T and C - G
Answer:
• There would be 20% Cytosine.
Adenine (30%) = Thymine (30%)
Guanine (20%) = Cytosine (20%)
Total of 100%
Chargaff’s Rules
• the amount of (A)denine will always equal
the amount of (T)hymine
• And
HOT!!!
• the amount of
(G)uanine will always
equal the amount
of (C)ytosine.
Nitrogenous Bases
• Why does A bond only with T and
C only with G?
• What do you notice?
Nitrogenous Bases
T and C are single-ring
Pyrimidines
A and G are double-ring
Purines
A single bonds with a
double
2 chains of nucleotides bind to form
a DNA molecule
• Hydrogen bonds form
between the
nitrogenous bases to
join the 2 chains
together
• The sugar and
phosphate group
together is known as
the sugar-phosphate
backbone
ENZYMES FOR DNA
REPLICATION
• Helicase = separates 2
DNA strands (breaks H
bonds)
• Primase=RNA primers at
INITIATION
REPLICATION ENZYMES
• Topoisomerase =
unwinding DNA
• DNA Polymerase = Adding
of DNA nucleotides
ELONGATION (proofread
and repair)
DNA REPLICATION ENZYMES
• LIGASE= Binds the
Okazaki fragments
• Watch the enzymes in
DNA Replication
Animation
AT and C-G Base Pairing
• DNA Replication simple version) (link)
• Media Showcase (cool animation link)
• Detailed Replication Link
DNA STRUCTURE
• A-T
• C-G
• in tons of
combinations
makes our
genetic code
DNA Replication
•Hi!...Still Awake?
•DNA Replication
Animation click here
What is the complementary base
sequence on the other strand of the
DNA?
A T T G C C C T A A
•
T
A A C G G G A T T
The Race is On!
• To Determine the Structure of the
DNA molecule.
Rosalind
Franklin
• Rosalind Franklin was an
English chemist who was
working in an X-ray
crystallography lab in Paris,
France in 1951.
FAMOUS
PHOTO 51
(correct
orientation
of DNA)double helix
• Taken
with her
PhD
student
Raymond
Gosling
Tells you there are 10
bases/turn
Linus Pauling
• American biochemist
suggested helix
(spiral)shape
• Most famous for
Vitamin C prevents
colds
DNA Geek
• Linus Pauling was a Caltech chemist
(USA), who in 1951 had discovered the
alpha helical nature of protein structure.
I remember his books: Vitamin C
and the Common Cold and Cancer
and Vitamin C also
The Nature of the Chemical Bond
and protested nuclear testing
DNA Geeks
• James Watson, a biologist from Indiana
University, and Francis Crick, a physicist,
were working at the Cavendish Lab in
Cambridge, England Nobel Prize for
structure of DNA
Francis Crick (1916-2004)
Narrative - 8. Watson and Crick - Linus Pauling and the Race for DNA: A
Documentary History
• Born in England
• Worked at Cambridge
Crick’s first
DNA
sketch
Worked on DNA structure
with Watson
James Watson (1928- )
• American age 22
• Ph.D. degree in Zoology in
1950
• Worked with Crick at the
King’s College on the
structure of DNA
• At age 12 starred on QUIZ
KIDS TV show
• Recently at Cold Spring
Harbor, NY, head of HGP
Watson and Crick
Met and worked at the
Cavendish Laboratory
Watson and Crick’s Wire Model
DOUBLE HELIX
Watson and Crick are
"Lucky“
youtube(2:21)
DNA Geek
Maurice Wilkins (1916-2004)
• New Zealand Born British Scientist
• It was his idea to study
DNA by X-ray
crystallographic
techniques
• Nobel Prize
DNA Base Pairs
• Adenine with Thymine
• Guanine with Cytosine
X ray Diffraction
Franklin’s Suggestion
DNA Bases
Franklin corrects Watson and
Crick
• Told them their first model was
incorrect
• They had put the bases on the
outside
The Scandal
• Watson used her pictures
(Photo 51) to determine that
DNA spirals into a double
helix.
•
Little did Rosalind
Franklin know that
her laboratory
colleague, Maurice
Wilkins, was in the
next room revealing
months of her work
to her competitor!
Rosalind Franklin
• Died of ovarian cancer at age
37 and so could not share in the
Nobel Prize
• Her work did lead the way to
work on viruses
Watson and Crick “stole” her
Photo 51 information
• She was not included in the
publication that reported the
structure of DNA and she died
before the Nobel Prize was given
to Watson and Crick.
Nobel Prize
• In 1962 James Watson,
Francis Crick, and Maurice
Wilkins jointly received the
Nobel Prize in medicine or
physiology for their
determination in 1953 of the
structure of deoxyribonucleic
acid (DNA).
• Mr. W's DNA Rap
Violation of the
Scientists' Code of
Honor
•
It is necessary for scientists to share
information with one another, for if they did
not, science and knowledge would not
develop and grow. However, the tacit
agreement among scientists who use or
borrow one another's findings is that proper
credit must be given to the author or
originator of the work.
Beadle and Tatum’s Experiment
• used X rays to cause mutations in
strains of the mold Neurospora (a bread
mold)
• were able to create single gene
mutations that incapacitated specific
enzymes
Beadle and Tatum
The One Gene/One Enzyme Hypothesis
Used bread mold
Beadle and Tatum
1941
George W. Beadle (1903-1989) and Edward L.
Tatum (1909-1975) show how genes direct the
synthesis of enzymes that control metabolic
processes
REVISED
BEADLE AND TATUM:
• One gene- one polypeptide
EXPLAIN:
•“The secret of life is
complementarity.”