Chromosomes and Karyotypes

Chromosomes and Karyotypes

What is a chromosome?

•  Chromosome- ______of ______and proteins

•  Chromatid- two ______copies of DNA that

make up a ______

•  Centromere- where the two chromatids ______

Terminology

•  Gene- ______of DNA that codes for a protein or RNA molecule

–  Units of ______

•  Homologous chromosomes- are chromosomes that are similar in ______, ______and genetic ______

•  Somatic cell- ______sperm or egg cell

–  Cheek, blood, brain, bone, liver, kidney

•  46 chromosomes in human somatic cells

–  23 ______

–  One set comes from the mother, the other from the father

•  A diploid (2n) cell contains ______of chromosomes, like the somatic cell

•  Gamete- ______or ______cell

–  Carries _____ set of chromosome (has 23 total chromosomes)

•  A haploid (n) cell contains only one set of chromosomes, like the gamete cell

•  Fertilization- ______of two gametes (fusion of sperm and egg)

•  Zygote- fertilized egg cell

–  The ______cell of a new individual

Haploid (n)

Diploid (2n)

n = 23

Sperm 23 chromosomes n

Egg + 23 chromosomes + n

Total 46 chromosomes 2n (diploid)

Chromosomal Mutations

•  Mutations- ______in an organisms chromosome ______

–  ______

–  ______

–  ______

–  ______

Original Chromosome:

Deletion- when a piece of chromosome ______completely

Duplication- a chromosome fragment ______to its homologous chromosome

Inversion- when the chromosome piece ______to the original chromosome but in a ______orientation

Translocation- when the chromosome piece reattaches to a ______chromosome

Differences among species

•  Each organism has a characteristic number of chromosomes

•  The number is ______with the species

•  Potatoes, plums, and chimpanzees all have 48 chromosomes

•  Oats, Raccoon Dogs, Rats, Wheat and Wolverines all have 42 chromosomes

Karyotypes

•  A karyotype is a ______of an organisms chromosomes

•  It allows us to study the difference of ______, ______and ______of each chromosome

•  Humans have ______of chromosomes

•  Sex chromosomes- the last pair (#23) on a karyotype that ______the ______of an individual

–  Females (XX)

–  Males (Xy)

•  ______- are all other chromosomes

•  During mitosis, a picture is taken

•  The chromosomes are sorted into ______and arranged from ______to ______

•  The 2 sex chromosomes are put at the ______(pair 23)

Nondisjunction

•  Sometimes during meiosis, the chromosomes fail to separate correctly (called nondisjunction)

–  Monosomy- when gamete has only 1 ______of the affected chromosome

–  ______- when the other gamete has ____ copies of one chromosome

Nondisjunction: Common Disorders

•  Klinefelter’s syndrome:

–  One to several extra _____ chromosomes

•  Ex. XXY or XXXY

•  Turner’s syndrome:

–  ______sex chromosome

–  Absense of Y develops into female

•  Ex. XO

•  Down’s Syndrome:

–  ______

–  Trisomy 21

–  Most common birth defect

•  Patau Syndrome:

–  Autosomal

–  ______

–  Rarely live past infancy

–  Neurological problems, polydactyl and facial defects

•  Edwards Syndrome:

–  Autosomal

–  ______

–  30% of babies die by 1 month

–  Learning disabilities, congenital heart defects and malformations of digestive tract, urinary tract and genitals