Be familiar with the term nondisjunction. Define the word nondisjunction on a post-it note. You must utilize your brain and/or the text book, not your technology.

Can you spot the differences? GAME TIME! Can you spot the differences?

How can we look at chromosomes? We look at chromosomes in something called a karyotype. A karyotype is an organized profile of a persons chromosomes.

¿¿Qué es un cariotipo ?? A karyotype is simply a picture of a person's chromosomes. In order to get this picture, the chromosomes are isolated, stained, and examined under the microscope. Most often, this is done using the chromosomes in the white blood cells. A picture of the chromosomes is taken through the microscope. Then, the picture of the chromosomes is cut up and rearranged by the chromosome’s size. The chromosomes are lined up from largest to smallest. A trained cytogeneticist can look for missing or extra pieces of chromosome. http://www.chromosome18.org/WhatIsaChromosome18Abnormality/BasicGenetics/WhatisaKaryotype/tabid/120/Default.aspx

HOMOLOGOUS CHROMOSOMES What do we call these?

What’s a homologous chromosome? Have genes for the same trait at the same location.

Normally, humans have 46 chromosomes in each cell Chromosome Numbers Normally, humans have 46 chromosomes in each cell 23 from our mother  23 from our father  Knowing these numbers is essential for scientists to tell if someone has a genetic disorder.

It is possible for a person to have more or less than 46 chromosomes More Numbers Since humans have 46 chromosomes that means they have 23 pairs of homologous chromosomes. It is possible for a person to have more or less than 46 chromosomes This results in a genetic disorder

What can looking at chromosomes tell us? Whether or not an individual has a genetic disorder. If there is a possibility that an unborn child could have a genetic disorder. If an unborn child will be male or female.

Discussion Points Would you want to know if your baby had a genetic disorder? What would be the benefits? What would be the consequences?

Karyotypes of Genetic Disorders

How do you end up with more or less chromosomes? Nondisjunction This happens when two chromosomes do not properly separate during the formation of gamates ( eggs and sperm).

Trisomy 21 1 in every 691 births

Trisomy 21

Trisomy 21 (Down Syndrome) Characteristics Deep creases across palms of hands Upward slant to eyes Heart defects Poor vision

Trisomy 21 (Down Syndrome)

Turner Syndrome 1 in every 2,500 female babies

Normal Female Turner Syndrome

Characteristics Turner Syndrome Short Stature Infertile ‘Webbed’ neck Heart Defects-constricted aorta

Turner Syndrome

Klinefelter’s Syndrome 1 in 500 to 1,000 newborn males

Klinefelter’s Syndrome

Klinefelter’s Syndrome Characteristics Occurs only in males Long Arms and Legs Weak Bones Low Testosterone Enlarged breast tissue

Klinefelter’s Syndrome

Jacob’s Syndrome (Supermale)

Jacob’s Syndrome (Supermale)

Triple X Syndrome (Superfemale)

Triple X Syndrome (Superfemale)

Karyotype Practice A. Male B. Female 2. A. Normal B. Abnormal

A. Male B. Female A. Normal B. Abnormal 3. A. Turner’s B. Klinefelter’s C. Down’s D. Super female

A. Male B. Female A. Normal B. Abnormal 3. A. Super female B. Turner’s C. Down’s D. Klinefelter’s

A. Male B. Female A. Normal B. Abnormal 3. A. Down’s B. Super female C. Cri du chat D. Turner’s E. None of the above

A. Normal B. Abnormal A. Down’s B. Klinefelter’s C. Turner’s D. Normal 3. A. Male B. Female 4. The genotype is: A. XXX B. XO C. XXY D. Normal

A. Normal B. Turner’s C. Klinefelter’s D. super female E. Down’s Syndrome 2. This karyotype shows a: A. sex – chromosome disorder B. Autosomal disorder C. Normal karyotype

A. Male B. Female A. Normal B. Abnormal

DNA Banding a.k.a DNA Fingerprinting Who Done It? Who are the Parents?

What is DNA banding? A technique for comparing the nucleotide sequences of fragments of DNA from different sources. DNA fingerprinting is often used to provide evidence in criminal law cases or determine the relatedness of two or more individuals.

What is DNA Profiling? A technique used by scientists to distinguish between individuals of the same species using only samples of their DNA 43

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. 44

Stages of DNA Profiling 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) 45

Stages of DNA Profiling Step 2: The DNA is cut into fragments using restriction enzymes. Each restriction enzyme cuts DNA at a specific base sequence. 46

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). 47

Stages of DNA Profiling 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. 48

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. 49

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. 50

Stages of DNA Profiling The pattern of fragment distribution is then analysed. 51

Uses of DNA Profiling DNA profiling is used to solve crimes and medical problems 52

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). 53

Biological materials used for DNA profiling Blood Hair Saliva Semen Body tissue cells DNA samples have been obtained from vaginal cells transferred to the outside of a condom during sexual intercourse. 54

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 (NB: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. 55

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: 56

Crime Scene Suspect 1 Suspect 2 Suspect 3

Was the suspect at the crime scene? Suspects Profile Blood sample from crime scene Victims profile 58

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 59

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. 60

Is this man the father of the child? Mother Child Man 61

Famous cases In 2002 Elizabeth Hurley used DNA profiling to prove that Steve Bing was the father of her child Damien 62

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. 63

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. 64

DNA Banding Person 1 2 3 4 5 6 7

DNA from crime scene Suspects’ DNA Person 1 2 3 4 5 6 7