Download What do these 3 people have in common?

What do these 3 people have in common?
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.
They are all American serial killers!!!
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 "supermale" syndrome where
men with this condition were thought to be overly aggressive and more likely to become
a criminal.
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 these observations, men with XYY syndrome were labeled as overly
aggressive and likely to be criminals.
It is now believed that though there is a disproportionate number of men in prison with
XYY Syndrome compared to the normal population. However, the numbers still are
not high enough to indicate that the syndrome is linked directly with violence.
A Karyotype of an XYY Person
2Y
chromosomes
How is this related to biology?
In order to get XYY syndrome, some biological error
must have happened that caused the individual to end
up with an extra Y chromosome
– What do you think may have happened to cause this error?
– What process do you think was involved?
Start with 4 chromosomes
Section 11-4: Meiosis
The word "meiosis" comes from the Greek meioun, meaning  "to make small,"
since it results in a  reduction in chromosome number in the gamete cell.
End with 2
chromosomes
A. Why is Meiosis Important?
Consider these Questions …
1. How many chromosomes would a human sperm or an egg
contain if either one resulted from the process of mitosis?
a. 46 chromosomes
2. If a sperm containing 46 chromosomes fused with an egg
containing 46 chromosomes, how many chromosomes would the
resulting fertilized egg contain? Do you think this would create any
problems in the developing embryo?
b. 46 + 46 = 92; a developing embryo would not survive if it
contained 92 chromosomes.
3. In order to produce a fertilized egg with the appropriate number of
chromosomes (46), how many chromosomes should each sperm
and egg have?
 c. Sperm and egg should each have 23 chromosomes.
*Meiosis  how you make sperm and egg cells with only 23 chromosomes*
B. Chromosome Number
1.  Number varies by organism
– a. Ex: turkey  82, fruit fly  6, human 46
2. Organisms that reproduce sexually have
pairs of similar chromosomes
– a. Called  HOMOLOGOUS CHROMOSOMES
– b. Similar in size, structure, and carry genes for the
 same traits (but may be different forms of the gene)
– c. Each member of a pair comes from  each parent
– d. Ex: humans have  23 pairs of homologous
chromosomes, or  46 total
i.  23 in sperm,  23 in egg, pair up
3. Diploid vs. Haploid
a. Diploid
– i.  Double set of chromosomes
– ii.  “2n”
– iii. Humans – 23 sets/pairs,
 2n = 46
b. Haploid
– i..  Single set of chromosomes
– ii.  “n”
– iii. Humans – one chromo. from
each set,  n = 23
4. Chromosome numbers & cell types
a. Somatic cells
– i. “Regular” body cells
– ii.  Always diploid
– iii. Humans  46 chromo.
b. Gametes
– i. “sex cells”
– ii. Usually egg & sperm (or
pollen/spores)
– iii.  Always haploid
– iv. Humans  23 chromo.
C. Phases of Meiosis
Meiosis I
1. Interphase I
– a. Cells undergo a round of  DNA replication,
forming duplicate chromosomes
2. Prophase I
– a. Each chromosome pairs with its corresponding
homologous chromosome to form a  tetrad
i. tetrad  contains 4 chromatids
– b. Homologous chromosomes exchange portions of
their chromatids
ii.  Called crossing over
tetrad
crossing-over
Crossing-Over
3. Metaphase I
– a.  Spindle fibers attach to the chromosomes
– b. Tetrads line up in the  middle of the cell
4. Anaphase I
– a. Fibers pull homologous chromosomes toward
 opposite ends of the cell
– b. Centromere  stays intact
5. Telophase I and Cytokinesis
– a.  Nuclear membranes form
– b. Cell separates into  2 cells
Meiosis II
1. Prophase II
– a. Meiosis I results in  2 haploid (N) daughter
cells each with  half the number of
homologous chromosomes as the original cell
2. Metaphase II
– a. Chromosomes line up in the  center of the cell
3. Anaphase II
– a. Paired  sister chromatids separate and move
towards  opposite ends of the cell
– b. Centromere  is broken
4. Telophase II and Cytokinesis
– a. Meiosis II results in  4 haploid (N) daughter
cells
– b. Each cell contains  half the number of
chromosomes as the original cell
Meiosis I
Tetrad = 4 chromatids
Homologous
chromosome
Meiosis II
Prophase II
Metaphase II
Meiosis I results in two
The chromosomes line up in a
haploid (N) daughter cells, similar way to the metaphase
each with half the number of stage of mitosis.
chromosomes as the original.
Anaphase II
The sister chromatids
separate and move toward
opposite ends of the cell.
Telophase II
Meiosis II results in
four haploid (N)
daughter cells.
D. Gamete Formation
Unequal
division of
cytoplasm
1. Males  4 sperm formed
2. Females  1 egg formed (larger)
and 2 polar bodies (smaller)
a.  only the egg is used in reproduction
E. Comparing Mitosis and Meiosis
Mitosis
1. Known as  cell division
2. Consists of  1 division
3. Forms  2 genetically
identical daughter cells
4. Daughter cells have 
same amount of chromosomes
as parent cell (humans = 46)
5. Occurs only in  body cells
– somatic cells
6. Purpose =  make more
body cells for growth and
repair
Meiosis
1. Known as  cell reduction division
2. Consists of  2 divisions
3. Forms  4 genetically different
daughter cells
4. Daughter cells have  half the
amount of chromosomes as the
parent cell (humans = 23)
5. Occurs only in  sex cells
– gametes
6. Purpose =  form egg and sperm
cells for fertilization
Meiosis Animations
1. Meiosis Overview
2. Animal Cell Meiosis
(Part 1)
3. Animal Cell Meiosis
(Part 2)
4. Crossing Over