Human Chromosomes

How many chromosomes do humans have?• 46

• In 23 pairs – one in each pair from mom, one from dad

• Matched pair = homologous chromosomesThey have the same genes in the same order

(but not necessarily the same alleles)

Homologous Chromosomes

• One in each pair from mother, the other from father

• Homologous pairs carry genes controlling the same inherited traits.

• Each locus (position of a gene) is in the same position on homologues.

Homologous Chromosomes

Eye color locus

Hitchhiker thumb locus

Karyotype

• A karyotype is an organized profile of a person's chromosomes. In a karyotype, --chromosomes are arranged and numbered by size, from largest to smallest. --used to find genetic diseases caused by chromosome problems

• To make a karyotype, scientists take a picture of someone's chromosomes, cut them out and match them up

Humans have 23 Sets of Homologous ChromosomesEach Homologous set is made up of 2 Homologues.

Homologue

Homologue

Autosomes(The Autosomes code for most of the offspring’s traits)

In Humans the “Autosomes” are sets 1 - 22

Sex Chromosomes

Sex ChromosomesThe Sex Chromosomes code for the sex of the offspring.

** If the offspring has two “X” chromosomes it will be a female. ** If the offspring has one “X” chromosome and one “Y” chromosome it will be a male.

XX chromosome - female XY chromosome - male

In Humans the “Sex

Chromosomes” are the 23rd set

X chromosome Y chromosome