DNA…and a little quick history…

1866

Gregor Mendel published the results of his investigations

of the inheritance of

"factors" in pea plants.

1950'sMaurice Wilkins (1916- ), Rosalind Franklin (1920-1957), Francis H. C. Crick

(1916- ) of Britain and James D. Watson (1928- )

of the U.S. discover chemical structure of DNA,

starting a new branch of science--molecular

biology.

1953Watson and Crick made a model of the DNA molecule and proved that genes

determine heredity.

The Late 1980'sAn international team of scientists began the

project to map the human genome. The first crime conviction based on DNA

fingerprinting, in Portland Oregon.

1994The FDA approved the first

genetically engineered food -- FlavrSavr tomatoes engineered for

better flavor and shelf life.

1995DNA testing in forensics cases gains fame in the

O.J. Simpson trial.

1997Dolly the Sheep - the first adult animal clone.

2000J. Craig Ventor, along with Francis Collins, jointly

announce the sequencing of the entire human genome.

DNA

DNA stands for deoxyribonucleic acid.

Where is DNA found?

James Watson and Francis Crick discovered that

chromosomes are made up of DNA and

called it a double helix. These

chromosomes are located in the

nucleus!!

The Double Helix…

…was determined to be a twisted

ladder of nucleotide

bases.

Nucleotide

NucleotideSugar

Phosphate

Base

DNA nucleotides are made up of…

Sugar

Phosphate

Base

Deoxyribose sugar

AdenineGuanineCytosineThymine

When the nucleotides

are assembled,

adenine pairs with thymine. Cytosine pairs with guanine.

Quick Quiz• Who discovered the arrangement of the

DNA molecule?Watson and Crick

• DNA is considered a ____ helix.double

• DNA is made up of what subunits?nucleotides

• What are the 3 components of a nucleotide?

sugar, phosphate, base

• In DNA, adenine pairs with____?thymine

DNA replication

• In order for cells to replicate during mitosis, the DNA must make a copy of itself. Why?

• Which phase of the cell cycle does the replication of DNA take place?

a) G1 - Interphaseb) S - Interphasec) G2 – Interphased) Prophase

Replication Sequence

1. Enzymes unwind the helix

2. Enzymes pull apart the DNA molecule

3. Exposed bases attract their complementary bases

4. Polymerase joins all the nucleotides together on each new strand

5. Mitosis begins in the cell

DNA Replicationanimations

• Short version: http://www.lewport.wnyric.org/jwanamaker/animations/DNA%20Replication.html

• Long version: http://www.lewport.wnyric.org/jwanamaker/animations/DNA%20Replication%20-%20long%20.html

• preAP: http://www.johnkyrk.com/DNAreplication.html

DNA Fingerprint

• With technology today, scientists use DNA for many reasons: convict criminals, release criminals, and even determine paternity.

• A DNA fingerprint is created in these cases. DNA fingerprinting is a technique used to distinguish between individuals of the same species using only samples of their DNA.

DNA Fingerprint

• In order to create a DNA fingerprint, scientists have to cut the DNA with an enzyme specifically known as a restrictive enzyme.

• Once it is cut, the DNA is then placed into an electrophoresis chamber.

DNA Fingerprint

• Electricity is added to the chamber, and the DNA segments will move. Since DNA is negatively charged, it will run away from the negative electrode.

http://www.lewport.wnyric.org/JWANAMAKER/animations/Chrom%26Elpho.html

Which of the following do YOU think is a DNA fingerprint?

A blood stain was found in Mrs.

Lowery’s classroom.

Which student was the blood

stain most likely from?

DNA samples were taken from a crime scene, the female victim and two suspects in a sexual

assault case. The victim’s boyfriend was also tested. The DNA ladders are used

to judge the sizes of the DNA fragments. Control samples are also run, to

ensure that the experiment is done correctly. Can you determine which suspect is

likely the criminal?

Do the children inherit ALL of the traits from ONLY 1 parent?

Is the D2 daughter actually the Dad’s child?

What is the deal with the S2 son?

Results from a single DNA fingerprint

analysis for a man and his four

different children are shown in the

figure. Which lane contains the DNA

of the father?

DNA Fingerprinting Activity

DNA Fingerprinting Activity It was early Thursday morning when the police were called out to

investigate a crime scene. Apparently, someone had broken into a jewelry store and stolen a case of Crown Jewels. Unfortunately, some

blood was left behind on the window sill. The suspect list has been narrowed to 4 people:

Suspect 1: Scandalous Stueart A widely known as a successful crime chief. Stueart has been known to brag that he could get by any security system. He said that he would prove it by someday taking the crown jewels. No stone has been known to have higher security.

Suspect 2: Mischievous McCurley She would kill to own the largest and most precious stone in the world. She has been known to run with the worst jewelry thieves in the US. She wants a diamond ring on her left hand so bad that she once threatened to cut the ring finger off of her own partner in crime.

Suspect 3: Maniac Melton Owns the largest private collection of precious stones in the world. He has offered millions of dollars for the Crown Jewels. Having been a member of the prestigious Ninja S.W.A.T. team, he has the talent and guts to pull of such a crime.

Suspect 4: Sir Shabay He is known for his vast collection of “bling bling”. He is one of Hollywood’s most famous jewelry dealers. Although he has never been caught in the act, it has long been suspected that he is, in some way, responsible for many large jewelry thefts in the area.

Restriction Enzyme1. Find the pattern below in your DNA sample. 2. Use a pipe cleaner and lay it down on all of

the “cut sites”.

CCGGGGCC

For example:

TACCGGAATTCCGGTAAAATGGCCTTAAGGCCATTT

3. Count the number of BASE PAIRS between each “cut site”

4. Draw a line on your chart to represent the fragments.

Restriction Enzyme

TACCGGAATTCCGGTAAAATGGCCTTAAGGCCATTT

4 8 6

DNA Fingerprinting Activity

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DNA Fingerprinting Activity