1. Chromosomes
“Colored Bodies”

2. Chromosomes carry genetic information
Chromosomes are wound up DNA

3. 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)

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

5. 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

6. Sex determination What causes Male and female? Female = XX Male = XY
Autosome vs sex chromosomes

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

8. Chromosomes are only visible during mitosis
Chromosomes must be photographed and sorted

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

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

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

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

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

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

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

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

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

18. 13 q -Syndrome Deletion of the long arm of chromosome 13.
Severe malformations of face