What do these 3 people have in common?What do these 3 people have in common?

They are all American serial killers!!!

Arthur Shawcross: The Genesee River Killer. In March 1988, he murdered 11 females often dumping their bodies in the Genessee River in Rochester, NY.

John Wayne Gacy: The Killer Clown Between 1972 and 1978, he murdered 33 boys and young men, 27 of whom were found buried under the floor of his house.

Bobbie Joe Long During an 8 month period in 1984, he murdered at least ten women in Tampa Bay area of Florida. The murders were extremely brutal.

What else do these 3 people have in common?What else do these 3 people have in common?

They all have a genetic disorder called XYY syndrome, which resulted from each of them receiving an extra Y chromosome from his father. (normal male = XY)

The XYY syndrome was previously considered the The XYY syndrome was previously considered the "supermale" syndrome"supermale" syndrome where men where men with this condition were thought to be overly aggressive and more likely to become a with this condition were thought to be overly aggressive and more likely to become a criminal. criminal.

These original stereotypes came about because several researchers in the 1960s found These original stereotypes came about because several researchers in the 1960s found a high number of men with XYY syndrome in prisons and mental institutes. Based on a high number of men with XYY syndrome in prisons and mental institutes. Based on these observations, men with XYY syndrome were labeled as these observations, men with XYY syndrome were labeled as overly aggressive and overly aggressive and likely to be criminalslikely to be criminals..

It is now believed that though there is a disproportionate number of men in prison with It is now believed that though there is a disproportionate number of men in prison with XYY Syndrome compared to the normal population. XYY Syndrome compared to the normal population. However, the numbers still are However, the numbers still are not high enough to indicate that the syndrome is linked directly with violence. not high enough to indicate that the syndrome is linked directly with violence.

A Karyotype of an XYY PersonA Karyotype of an XYY Person

2 Y chromosomes

How is this related to biology?How is this related to biology?

In order to get XYY syndrome, some biological error In order to get XYY syndrome, some biological error must have happened that caused the individual to end must have happened that caused the individual to end up with an extra Y chromosomeup with an extra Y chromosome– What do you think may have happened to cause this error?What do you think may have happened to cause this error?– What process do you think was involved?What process do you think was involved?

Section 11-4: MeiosisSection 11-4: MeiosisThe word "meiosis" comes from the Greek meioun, meaning "to make small," since it results in a reduction in chromosome number in the gamete cell.

Start with 4 chromosomes

End with 2 chromosomes

A. Why is Meiosis Important?A. Why is Meiosis Important?

1. How many chromosomes would a human sperm or an egg 1. How many chromosomes would a human sperm or an egg contain if either one resulted from the process of mitosis?contain if either one resulted from the process of mitosis?

a. 46 chromosomes46 chromosomes2. If a sperm containing 46 chromosomes fused with an egg 2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any resulting fertilized egg contain? Do you think this would create any problems in the developing embryo?problems in the developing embryo?

b. 46 + 46 = 92; a developing embryo would not survive if it 46 + 46 = 92; a developing embryo would not survive if it contained 92 chromosomes.contained 92 chromosomes.

3. In order to produce a fertilized egg with the appropriate number of 3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm chromosomes (46), how many chromosomes should each sperm and egg have?and egg have?

c. c. Sperm and egg should each have 23 chromosomes. Sperm and egg should each have 23 chromosomes.

Consider these Questions …

*Meiosis how you make sperm and egg cells with only 23 chromosomes*

B. Chromosome NumberB. Chromosome Number

1. 1. Number varies by organismNumber varies by organism– a. Ex: turkey a. Ex: turkey 8282, fruit fly , fruit fly 66, human , human 4646

2. Organisms that reproduce sexually have 2. Organisms that reproduce sexually have pairs of similar chromosomespairs of similar chromosomes– a. Calleda. Called HOMOLOGOUS CHROMOSOMESHOMOLOGOUS CHROMOSOMES– b. Similar in size, structure, and carry genes for the b. Similar in size, structure, and carry genes for the

same traitssame traits (but may be different forms of the (but may be different forms of the gene)gene)

– c. Each member of a pair comes from c. Each member of a pair comes from each parenteach parent– d. Ex: humans have d. Ex: humans have 23 pairs23 pairs of homologous of homologous

chromosomes, or chromosomes, or 4646 total totali. 2323 in sperm, in sperm, 2323 in egg, pair up in egg, pair up

a. Diploida. Diploid– i. DoubleDouble set of chromosomes set of chromosomes– ii. ii. “2n”“2n”– iii. Humans – 23 sets/pairs, iii. Humans – 23 sets/pairs,

2n = 462n = 46

b. Haploidb. Haploid– i.. SingleSingle set of chromosomes set of chromosomes– ii. ii. “n”“n”– iii. Humans – one chromo. from iii. Humans – one chromo. from

each set, each set, n = 23n = 23

3. Diploid vs. Haploid

4. Chromosome numbers & cell types4. Chromosome numbers & cell types

a. Somatic cellsa. Somatic cells– i. i. “Regular” body cells“Regular” body cells– ii. ii. Always diploidAlways diploid– iii. Humans iii. Humans 46 chromo.46 chromo.

b. Gametesb. Gametes– i. i. “sex cells”“sex cells”– ii. Usually egg & sperm (or ii. Usually egg & sperm (or

pollen/spores)pollen/spores)– iii. iii. Always haploid Always haploid – iv. Humans iv. Humans 23 chromo.23 chromo.

C. Phases of MeiosisC. Phases of MeiosisMeiosis IMeiosis I

1. Interphase I1. Interphase I– a. Cells undergo a round of a. Cells undergo a round of DNA replication, DNA replication,

forming duplicate chromosomesforming duplicate chromosomes

2. Prophase I2. Prophase I– a. Each chromosome pairs with its corresponding a. Each chromosome pairs with its corresponding

homologous chromosome to form a homologous chromosome to form a tetradtetradi. i. tetrad tetrad contains 4 chromatidscontains 4 chromatids

– b. Homologous chromosomes exchange portions of b. Homologous chromosomes exchange portions of their chromatidstheir chromatids

ii. ii. Called Called crossing overcrossing over

tetrad

crossing-over

Crossing-Over

3. Metaphase I3. Metaphase I– a. a. Spindle fibersSpindle fibers attach to the chromosomes attach to the chromosomes– b. Tetrads line up in the b. Tetrads line up in the middle of the cell middle of the cell

4. Anaphase I4. Anaphase I– a. Fibers pull homologous chromosomes toward a. Fibers pull homologous chromosomes toward

opposite ends of the cellopposite ends of the cell– b. Centromere b. Centromere stays intactstays intact

5. Telophase I and Cytokinesis5. Telophase I and Cytokinesis– a. a. Nuclear membranesNuclear membranes form form– b. Cell separates into b. Cell separates into 2 cells2 cells

Meiosis IIMeiosis II1. Prophase II1. Prophase II– a. Meiosis I results in a. Meiosis I results in 2 haploid (N) daughter 2 haploid (N) daughter

cellscells each with each with halfhalf the number of the number of homologous chromosomes as the original cellhomologous chromosomes as the original cell

2. Metaphase II2. Metaphase II– a. Chromosomes line up in the a. Chromosomes line up in the center of the cellcenter of the cell

3. Anaphase II3. Anaphase II– a. Paired a. Paired sister chromatidssister chromatids separate and move separate and move

towards towards opposite ends of the cellopposite ends of the cell– b. Centromere b. Centromere is brokenis broken

4. Telophase II and Cytokinesis4. Telophase II and Cytokinesis– a. Meiosis II results in a. Meiosis II results in 4 haploid (N) daughter 4 haploid (N) daughter

cellscells– b. Each cell contains b. Each cell contains half half the number of the number of

chromosomes as the original cellchromosomes as the original cell

Meiosis IMeiosis I

Tetrad = 4 chromatids

Homologous chromosome

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

D. Gamete FormationD. Gamete Formation

1. Males 4 sperm formed 2. Females 1 egg formed (larger) and 2 polar bodies (smaller) a. only the egg is used in reproduction

Unequal division of cytoplasm

E. Comparing Mitosis and MeiosisE. Comparing Mitosis and Meiosis

MitosisMitosis1. Known as 1. Known as cell divisioncell division2. Consists of 2. Consists of 1 division1 division3. Forms 3. Forms 2 genetically 2 genetically identical daughter cellsidentical daughter cells4. Daughter cells have 4. Daughter cells have same same amount of chromosomes amount of chromosomes as parent cell (humans = 46)as parent cell (humans = 46)5. Occurs only in 5. Occurs only in body cellsbody cells– somatic cellssomatic cells

6. Purpose = 6. Purpose = make more make more body cells for growth and body cells for growth and repairrepair

MeiosisMeiosis1. Known as 1. Known as cell reduction divisioncell reduction division2. Consists of 2. Consists of 2 divisions2 divisions3. Forms 3. Forms 4 genetically different 4 genetically different daughter cellsdaughter cells4. Daughter cells have 4. Daughter cells have halfhalf the the amount of chromosomes as the amount of chromosomes as the parent cell (humans = 23)parent cell (humans = 23)5. Occurs only in 5. Occurs only in sex cellssex cells– gametesgametes

6. Purpose = 6. Purpose = form egg and sperm form egg and sperm cells for fertilizationcells for fertilization

Meiosis AnimationsMeiosis Animations1. Meiosis Overview1. Meiosis Overview2. Animal Cell Meiosis 2. Animal Cell Meiosis (Part 1)(Part 1)3. Animal Cell Meiosis 3. Animal Cell Meiosis (Part 2)(Part 2)4. Crossing Over4. Crossing Over