1. Packaged Instructions for Life
Chromosomes
Packaged Instructions for Life

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

3. Gene: segment of DNA that codes for specific proteins
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 (able to live) offspring
Fertilized egg = zygote = =

8. called homologous chromatids (similar info)
Diploids have same gene (eye color) but may have different variations (brown vs. blue eyes)
called homologous chromatids (similar info)
One from mother, one from father
gene for eye color (mom’s brown eyes)
dad’s blue eyes

10. 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

11. Typical Karyotype w/ 23 Chromosome Pairs
female
male

12. Karyotypes are usually only completed for cases where there might be a chromosomal abnormality
Monosomy (missing homolog)
Trisomy (Extra homolog)
Incorrect sex chromosome numbers

13. 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)

14. Down Syndrome
Trisomy 21 (3 #21 chromosomes) resulting in mental retardation
1 in 1,300 at age 25
1 in 1,000 at age 30
1 in 400 at age 35
1 in 100 at age 40
1 in 35 at age 45

15. He was born with an extra #21

16. Edward Syndrome
Trisomy 18 (3 #18 chromosomes) resulting in medical complications that usually result in 50% stillbirths & high mortality rate in general
1 in 5,000 births

17. Patau Syndrome
Trisomy 13 (3 #13 chromosomes) resulting in cleft lip or palate, close-set eyes, severe mental retardation
1 in 16,000 births

18. Turner Syndrome Females with monosomy (missing) X (also shown as XO)
1 in 2,500 girls

19. Triple-X Syndrome Females with XXX (or XXXX or XXXXX)
No physical defects, some have learning disabilities, tall stature
1 in 1,000 girls

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

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

22. Chromosomal mutations
Breakage of entire chromosome, and sometimes reattachment can lead to four types of drastic mutations that may involve MANY genes:
Deletion
Duplication
Inversion
Translocation
Effects depend on number of genes involved and on which chromosome F G H A B C D E A B C D E

23. Deletion Segment of chromosome gets deleted (missing genes) A B C D E
after
before

24. Deletion disorders Cri-du-chat (cat cry) syndrome
deletion on chromosome 5
children have a cat-like, high-pitched cry during infancy
mental retardation and physical abnormalities
About 1 in 20,000 to 50,000 babies is born with this disorder
Allie Wallace, left, who is 5, and Katie Castillo, who is 20, both have "cri du chat" or cat cry syndrome, a rare genetic disorder that causes an array of mental and physical impairments.

25. Prader-Willi syndrome
deletion on chromosome 15
mental retardation or learning disabilities, behavioral problems and short stature
may develop extreme obesity
About 1 in 10,000 to 25,000 babies is affected.

26. 22q11 deletion syndrome Specific deletions on chromosome 22
About 1 in 4,000 babies born
deletions cause a variety of problems that can include heart defects, cleft lip/palate, immune system abnormalities, characteristic facial features and learning disabilities
Certain combinations of these features are sometimes called DiGeorge or velocardiofacial syndrome.
Individuals with this disorder have a 50- percent chance of passing the chromosomal abnormality on to their offspring with each pregnancy.

27. Wolf-Hirschhorn syndrome
deletion on chromosome 4
characterized by mental retardation, heart defects, poor muscle tone, seizures and other problems
affects about 1 in 50,000 babies

28. Duplication A B C D E A B C D E
Segment of chromosome gets attached to normal chromosome, duplicating certain genes F G H F G H
before
after

29. Duplication disorders
Charcot-Marie-Tooth disease
Duplication on chromosome 17
destroys muscle tissue and hinders the sense of touch
breaks down strong tissue and cripples the hands & feet
one of the most common inherited neurological disorders, with 36 in 100,000 affected
The lack of muscle, high arch, and hammer toes are signs of the genetic disease.

30. Inversion A B C D E A B D C E
Segment of chromosome gets broken off, then reattached upside down F G H F G H
before
after

31. Inversion disorders Norrie Disease
Causes blindness and oftentimes hearing loss
Some mental retardation
On X chromosome
All males affected
Females affected only if occurs on both X (otherwise are carriers)

32. Translocation A B C D X Y E
Segments of gene from one chromosome get broken off and reattached to a different chromosome A B C D E F G H F G H
before
after

33. Translocation disorders
Many common disorders
Infertility (13 to14)
Schizophrenia (1 to 11)
Certain leukemias (1 to 12; 17 to 15)
Certain sarcomas (11 to 22)
Certain lymphomas (11 to 14; 5 to 1; 8 to 14)