Packaged Instructions for Life

Presentation on theme: "Packaged Instructions for Life"— Presentation transcript:

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

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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