1. Chromosomes
“Colored Bodies”

2. Chromosomes carry genetic information
Chromosomes are wound up DNA

3. Mitosis ensures identical daughter cells
Each has same number of chromosomes

4. Diploid – Every body cell has 2 sets of chromosomes
n = number of chromosomes
Normal body cells have 2n (2 x n) chromosomes
Humans have 23 pairs = 46 chromosomes
2n = Diploid (double)

5. Cell cycle chromosome numbers
G1 – normal growing cell =
S – DNA duplicates =
G2 – cell grows =
M – Mitosis, cell divides 2n
2n  4n 4n
4n  2n

6. Haploid - Sex Cells
Sexual reproduction Produces sperm and egg with only one set of chromosomes (1n)
1n = haploid (half)
Sperm = 1n Egg = 1n
Fertilized zygote = 2n

7. Meiosis
The process of producing sperm and eggs with only half the normal number of chromosomes.
Cell divides twice!

8. Sex determination
What causes Male and female?
Female
= XX
Male
= XY

9. Karyotype
Sorting chromosomes photo to check for chromosome abnormalities
What is the sex of this patient?
Male = XY

10. Chromosomes only visible in mitosis
Chromosomes must be photographed and sorted

11. Chromosomal mutations
All mutations listed in Karyotype lab

12. Non – Disjunction When chromosomes do not separate during meiosis
This forms an abnormal number of chromosomes in sex cells
Trisomy – 3
Monosomy – 1

13. Down’s syndrome - Trisomy 21
extra 21st chromosome
Characteristic facial flattening
Decreased mental ability

14. Edward’s Syndrome - Trisomy 18
Extra 18th chromosome
Organ and body
deformation
Early death.

15. Patua Syndrome or Trisomy 13
Extra chromosome 13
Early Death.
External symptoms are similar to Edward's.
Cleft palate

16. Turner syndrome = XO female
Only one X chromosome
short stature
Broad / thick
lack of
secondary
sex characteristics

17. Klinefelter Syndrome - XXY male
Male with Slight female characteristics
lower IQ and mild
mental handicap

18. Trisomy X - XXX female lowered intelligence.
lack of secondary sex characteristics.
Sterile
Can be “normal”

19. Deletion
Removal of a chromosome segment

20. Cri du Chat (cat cry) Syndrome
Deletion of a small arm of chromosome 5
cat-like cry
round face, heart disease
mental handicap.

21. Wolf-Hirschhorn Syndrome
Deletion of a segment of chromosome 4's short arm.
Affects scalp, nose, lips, palate

22. 13 q -Syndrome Deletion of the long arm of chromosome 13.
Severe malformations of face

23. Other chromosome problems

24. Duplication Repeats a segment of DNA/ gene ABABCD
Antifreeze in ice fish

25. Inversion Reverse a segment ACBDEF
Ex. white throat/tan striped sparrows

26. Translocation
A segment from one chromosome joins a non homologous chromosome
ABCLMNDE
Leukemia
Infertility