1. Packaged Instructions for Life
Chromosomes

2. Structure
Chromosomes are packages of DNA wrapped with proteins called histones
Composed of two identical sister chromatids attached at centromere

3. Each sister chromatid contains thousands of identical genes in the same locations on each
Gene: segment of DNA that codes for specific proteins
Ex: hair color, eye color, lip shape, etc
Gene A
Gene B
Gene C
Gene D
Gene E

4. Each human somatic or body cell contains two copies of each chromosome
23 sets of chromosomes x 2 = 46 total (other species differ in numbers)
Combination of all 23 is TOTAL DNA genome (3 billion base pairs)

5. One set (23rd) contains sex chromosomes X and/or Y
Females have XX
Males have XY (Y is just shorter)
Males: XY
Females: XX

6. Two sets of chromosomes = diploid (somatic cells)
One set of chromosomes = haploid (gametes)
Necessary since combination of chromosomes from egg & sperm must be diploid to produce viable (liveable) offspring
Fertilized egg = zygote

8. Map of all 23 sets of chromosomes from a body/somatic cell is called a karyotype
Numbered from 1 – 23 based on length, location of centromere, and banding pattern

9. Typical Karyotype w/ 23 Chromosome Pairs
female
male

10. Karyotypes are usually only completed for cases where there might be a chromosomal abnormality
Missing homologue
Extra homologue
Incorrect sex chromosome numbers

11. Chromosomal abnormalities
Result of mistakes in gamete production (meiosis)
Each gamete (sperm & egg) is haploid
Duplication of gamete can result in accidents causing 2 or more sets of specific chromosome (rather than necessary 1 set)

12. Down Syndrome
Trisomy 21 (3 #21 chromosomes) resulting in mental retardation
1 in 700 births (higher for women over 40)

13. He was born with an extra #21

14. Edward Syndrome
Trisomy 18 (3 #18 chromosomes) resulting in medical complications that usually result in 50% stillbirths & high mortality rate in general
1 in 3,000 births

15. Patau Syndrome
Trisomy 13 (3 #13 chromosomes) resulting in cleft lip or palate, close-set eyes, severe mental retardation
1 in 10,000 births

16. Turner Syndrome
Females missing X (XO)
1 in 5,000

17. Triple-X Syndrome Females with XXX (or XXXX or XXXXX)
Infertility (most), learning disabilities, tall stature
1 in ,000

18. Klinefelter Syndrome
Males with XXY or XXXY
1 in 1,000
Low levels of testosterone, female-like features, infertile

19. Jacobs or Super Male Syndrome
Males with XYY
1 in 2000
Mostly average, but excess acne, very tall, slightly increased aggression

20. translocation