Chromosomes “Colored Bodies”

Chromosomes carry genetic information Chromosomes are wound up DNA

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)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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