Bellwork: Copy down the question breakdown for the test tomorrow

• Cell Cycle/Mitosis = 10 questions• Cancer = 4 questions• Meiosis = 4 questions• Karyotypes/DNA fingerprinting = 4 questions• Old Standards = 5 questions• Total = 27 questions

**Be prepared to tell me if you’d rather review and take notes over DNA fingerprinting or do a DNA fingerprinting webquest**

1. Biologically speaking, what is cancer?

A. a viral infectionB. a disease caused by uncontrolled

cell growthC. a sign of the zodiacD. a type of cell differentation

2. Which of the following statements about meiosis is false?

A. It produces gametes B. It occurs in the testes or ovaries

(gonads)C. It enables an organism to grow and

repair itselfD. It causes genetic variation due to

crossing over

3. Crossing over in meiosis causes..

A. Identical cellsB. Genetic variation (diversity)C. MutationsD. Cancer

4. In an organism with 24 chromosomes; mitosis produces ______, while meiosis produces ______

A. Mitosis = (12) haploid gametes; meiosis = (24) diploid body cells

B. Mitosis = (12) haploid body cells; meiosis = (24) diploid gametes

C. Mitosis = (24) diploid gametes; meiosis = (12) haploid body cells

D. Mitosis = (24) diploid body cells; meiosis = (12)haploid gametes

5. Which disorder is depicted in the karyotype below?

A. This is a normal karyotype

B. Trisomy 21C. Missing an X

chromosomeD. Partial deletion of

chromosome 3

6. Which of the following is not a good source of DNA to create a DNA fingerprint?

A. BloodB. SalivaC. SkinD. Fingerprints

7. When less mature cells divide too rapidly, this can lead to the development of---

A. AllergiesB. TumorsC. Cardiovascular diseaseD. AIDS

8. How are skin and muscle cells different?

A. Skin cells have smaller chromosomesB. Muscle cells have more chromosomesC. They express different genesD. Muscle cells are mutated skin cells

9. What occurs during the S phase of the cell cycle?

A. The cell growsB. The cell dividesC. The cell replicates its DNAD. The cell mutates

10. Chromosomes line up at the cell’s equator during --

A. ProphaseB. MetaphaseC. AnaphaseD. Telophase

Answer Key

1. Biologically speaking, what is cancer?

A. a viral infectionB. a disease caused by uncontrolled

cell growthC. a sign of the zodiacD. a type of cell differentation

2. Which of the following statements about meiosis is false?

A. It produces gametes B. It occurs in the testes or ovaries

(gonads)C. It enables an organism to grow and

repair itself (MITOSIS)D. It causes genetic variation due to

crossing over

3. Crossing over in meiosis causes..

A. Identical cellsB. Genetic variation (diversity)C. MutationsD. Cancer

4. In an organism with 24 chromosomes; mitosis produces ______, while meiosis produces ______

A. Mitosis = (12) haploid gametes; meiosis = (24) diploid body cells

B. Mitosis = (12) haploid body cells; meiosis = (24) diploid gametes

C. Mitosis = (24) diploid gametes; meiosis = (12) haploid body cells

D. Mitosis = (24) diploid body cells; meiosis = (12)haploid gametes

5. Which disorder is depicted in the karyotype below?

A. This is a normal karyotype

B. Trisomy 21C. Missing an X

chromosomeD. Partial deletion of

chromosome 3

6. Which of the following is not a good source of DNA to create a DNA fingerprint?

A. BloodB. SalivaC. SkinD. Fingerprints

7. When less mature cells divide too rapidly, this can lead to the development of---

A. AllergiesB. Tumors (Cancer)C. Cardiovascular diseaseD. AIDS

8. How are skin and muscle cells different?

A. Skin cells have smaller chromosomesB. Muscle cells have more chromosomesC. They express different genesD. Muscle cells are mutated skin cells

9. What occurs during the S phase of the cell cycle?

A. The cell growsB. The cell dividesC. The cell replicates (duplicates) its DNAD. The cell mutates

10. Chromosomes line up at the cell’s equator during --

A. ProphaseB. MetaphaseC. AnaphaseD. Telophase

What is DNA Profiling?

A technique used by scientists to distinguish between individuals of the same species

using only samples of their DNA

Who Invented it?

• The process of DNA fingerprinting was invented by Alec Jeffreys at the University of Leicester in 1985.

• He was knighted in 1994.

Stages of DNA Profiling

• Stage 1: Cells are broken down to release DNA

If only a small amount of DNA is available it can be amplified using the polymerase chain reaction (PCR)

Stages of DNA Profiling Stage 2: The DNA is cut into fragments using restriction enzymes,

which cut the DNA at a specific base sequence

Stages of DNA Profiling

• The sections of DNA that are cut out are called restriction fragments.

• This yields thousands of restriction fragments of all different sizes because the base sequences being cut may be far apart (long fragment) or close together (short fragment).

Stages of DNA Profiling

Stage 3:• Fragments are

separated on the basis of size using a process called gel electrophoresis.

• DNA fragments are injected into wells and an electric current is applied along the gel.

Stages of DNA Profiling

DNA is negatively charged so it is attracted to the positive end of the gel.

The shorter DNA fragments move faster than the longer fragments.

DNA is separated on basis of size.

Stages of DNA Profiling

• A radioactive material is added which combines with the DNA fragments to produce a fluorescent image.

• A photographic copy of the DNA bands is obtained.

Stages of DNA Profiling

Stage 4:• The pattern of fragment distribution

is then analyzed. – AKA where the bands are on the gel

DNA samples can be obtained

from blood, hair,

urine, saliva, skin,

semen, or

vaginal secretions.

Uses of DNA Profiling

• DNA profiling is used to solve crimes and medical problems

Crime

• Forensic science is the use of scientific knowledge in legal situations.

• The DNA profile of each individual is highly specific.

• The chances of two people having exactly the same DNA profile is 30,000 million to 1 (except for identical twins).

DNA Profiling can solve crimes

• The pattern of the DNA profile is then compared with those of the victim and the suspect.

• If the profile matches the suspect it provides strong evidence that the suspect was present at the crime scene (it does not prove they committed the crime).

• If the profile doesn’t match the suspect then that suspect may be eliminated from the enquiry.

Example

• A violent murder occurred. • The forensics team retrieved a blood

sample from the crime scene. • They prepared DNA profiles of the

blood sample, the victim and a suspect as follows:

Was the suspect at the crime scene?

Suspects Profile

Blood sample from crime scene

Victims profile

Solving Medical Problems

DNA profiles can be used to determine whether a particular person is the parent of a child.

A childs paternity (father) and maternity(mother) can be determined.

This information can be used in• Paternity suits• Inheritance cases• Immigration cases

Baby Daddy?

Example: A Paternity Test

• By comparing the DNA profile of a mother and her child it is possible to identify DNA fragments in the child which are absent from the mother and must therefore have been inherited from the biological father.

Is this man the father of the child?

Mother Child Man

Famous cases

• In 2002 Elizabeth Hurley used DNA profiling to prove that Steve Bing was the father of her child Damien

Famous Cases

• Colin Pitchfork was the first criminal caught based on DNA fingerprinting evidence.

• He was arrested in 1986 for the rape and murder of two girls and was sentenced in 1988.

Famous Cases

• O.J. Simpson was cleared of a double murder charge in 1994 which relied heavily on DNA evidence.

• This case highlighted lab difficulties.

Virtual Gel Electrophoresis

Practice, practice, practice!

• You have the rest of the period to complete the analysis worksheet.• Due at the end of the class.• Yes, it is for a grade!

• EXTRA CREDIT: Webquest