Non-Disjunction (manually typed)

the failure of chromosome pairs to separate either during meiosis I or meiosis II

nondisjunction

fertilization of an egg whose chromosomes have experienced nondisjunction will result in

a zygote with an abnormal number of chromosomes

two types of chromosome number alterations:

aneuploidy and polyploidy

occurs when a gamete has an abnormal number of chromosomes and unites with a normal gamete

aneuploidy

the zygote has an extra copy of a chromosome

trisomy

the zygote is missing a chromosome

monosomy

trisomy 21

down’s syndrome

turner syndrome

short stature, ears protruding outward, webbed neck

occurs when an organism has extra full sets of chromosomes

polyploidy

compare and contrast somatic cells with gametes

somatic cells are diploids, gametes are haploids

describe what a karyotype is

a visual representation of a person's chromosomes; a way to characterize the chromosomes

how can we distinguish a human somatic cell from a gamete using a karyotype

if they are in pairs or not

how many chromosomes would a human somatic cell have with trisomy

47

describe in detail the chromosome abnormality that causes Down’s syndrome

Error in metaphase (don’t line up properly) or anaphase (are not separated properly), resulting in two cells having too many chromosomes and two cells having too little chromosomes

Describe what amniocentesis is

a medical procedure that involves collecting a sample of amniotic fluid from the uterus during pregnancy

What two things can result in after fertilization if aneuploidy occurs in a gamete

a miscarriage or a live birth with a chromosomal abnormality and associated birth defects