The Human GenomeKaryotype: When chromosomes are photographed, then paired to observe size and number.Human Body Cell: Has 46 chromosomes, 2 of the 46 chromosomes are sex chromosomes and the remaining 44 are autosomal chromosomes23rd pair of a Female is XX23rd pair of a Male is XY

Normal Human Karyotype

Normal Karyotype

Nondisjunction

Failure of homologous pairs of chromosomes to separate properly during meiosis.

This results in cells with an uneven number of chromosomes

Down Syndrome

Down syndrome is caused by a person having three copies of chromosome 21 instead of two copies.

Down Syndrome

Patient has 47 chromosomesSome characteristics are: short, broad hands; short

height; broad head; round face; large tongue; slanting eyes and mental retardation

Down syndrome

Patau SyndromeCaused by an

extra copy of chromosome 13.

Severe mental deficiency, polydactylism, cleft lip/palate,

heart problems low survival rate

after 3 months.

Patau Syndrome

Facial Clefting shown to the right

Patau Syndrome

Klinefelter’s syndrome

Patient has 47 or 47+ chromosomes. (One to several extra X or Y)

MaleCharacteristics:

small testes, female-like breasts, female-like voice and retardation

Klinefelter’s Syndrome

Extra Y Chromosome

Patient has 47 chromosomes (one extra Y chromosome.

male1 in 1000 males have 47-XYYSlightly taller, but rather normal

development

Turner’s Syndrome

Patient has 45 chromosomes

Missing one X.

Female, sterile

dwarfism