Name: ____________________ Period: _____

DNA 1. What is DNA?

DNA stands for ____________________ _________ and contains _____________ information.

It is found on ___________________ located in the nucleus of our cells.

2. What makes up a DNA molecule?

The sides or ____________________ of the DNA molecule are made up of ____________________

(deoxyribose) and ____________________ molecules.

The rungs that form the middle of the molecule are made up of pairs of ____________________ or nitrogen

bases. ____________________ (A) pairs with ____________________ (T), while ____________________

(G) always pairs with ____________________ (C).

The ____________________ of the bases determines the genetic ____________________.

Label the diagram using the words listed below. Backbone Nitrogen Bonds Adenine Thymine Cytosine Guanine

3. How can DNA be used as evidence?

Each person’s DNA is ____________________ from other people (except identical twins).

DNA collected from a crime scene can either link a ____________________ to the evidence or

____________________ a suspect, similar to the use of fingerprints.

DNA can identify a victim through DNA from ____________________, even when no body can be found.

DNA can ____________________ crime scenes together by linking the same perpetrator to different scenes.

DNA can place an ____________________ at a crime scene, in a home, or in a room where the suspect claimed

not to have been.

DNA can _________________ a claim of self-defense and put a __________________ in the suspect's hand.

It can change a story from an ____________________ to one of ____________________.

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4. What factors can affect DNA evidence?

Environmental factors (e.g., __________________, sunlight, __________________, __________________, and mold) can affect DNA. Therefore, not all DNA evidence will result in a usable DNA profile. Further, DNA testing cannot identify __________________ the suspect was at the crime scene or for _______ _____________. DNA profiles from individuals convicted of certain crimes, such as rape, murder, and child abuse, are entered into _____________ and help officers identify possible suspects when no prior suspect existed.

5. What is CODIS?

CODIS stands for ____________________ ______________ _______________ _______________, which is an

electronic ____________________ of DNA profiles that can identify suspects.

6. Which three statements below are true?

_____ 1. The DNA in a man's blood is the same as the DNA in his skin cells and saliva.

_____ 2. Each person's DNA is different from every other individual's.

_____ 3. DNA can be found in all the cells in our bodies except the blood cells.

_____ 4. DNA can have forensic value even if it is decades old.

_____ 5. DNA evidence was first used to get a conviction in a trial in 1987.

7. The Killer's Trail – Watch the video and then choose the best answer for each question.

a Who was the victim? A. Marilyn Sheppard B. Sam Sheppard C. Sam Sheppard, Jr.

b What are the keys to DNA fingerprinting? A.Chromosomes B. Alleles C. Nitrogen bases

c Where did the scientist get the sample of DNA for Marilyn Sheppard? A. Hair B. Skin C. Fingernail

d Whose blood was found in the blood trail? A. Marilyn Sheppard B. Sam Sheppard C. Neither

DNA Fingerprinting: Gel Electrophoresis ___________ Fingerprints identify people at the molecular level.

_________ Electrophoresis is used to separate DNA fragments by size.

--A DNA sample is cut with restriction _____________

--Electrical current pulls DNA fragments through a gel.

A DNA fingerprint is a type of restriction _____________.

DNA fingerprints are based on parts of an individual’s DNA that can be used for identification.

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--based on noncoding regions of DNA that have ___________________ DNA sequences

---number of ______________ differs between people

A DNA fingerprint is ___________ actually a fingerprint!

Blood found at crime scene

--Need to determine if it is the ______________ blood, or the victim’s blood

---We can use DNA fingerprinting to find out if the DNA found at the crime scene belongs to the ______________________

Make a DNA fingerprint (restriction map) based on the DNA sequence repeats

DNA fingerprinting is used for identification.

DNA fingerprinting depends on the probability of a match.

--Many people have the_____________ number ofrepeats in a certainregion of DNA.

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---The probability that two people share identicalnumbers of repeats inseveral locations isvery very _______________.

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