Complex Traits and Chromosomal Abnormalities

What is aneuploidy?

abnormal number of chromosomes

What is nondisjunction?

When homologous chromosomes or sister chromatids fail to separate

Which step of meiosis does nondisjunction happen?

Anaphase

What is trisomy?

When there is an extra chromosome due to nondisjunction

What is monosomy?

When there is one less/missing chromosome due to nondisjunction

What is it called when there are the correct number of chromosomes?

Euploidy

What is Trisomy 21 usually called?

Down Syndrome

Does Trisomy 21 usually happen during Meiosis I or II?

Meiosis I

What is the number of gene copies in a cell called?

Gene dosage

Overproduction of _________ interfere with normal cellular function

genetic products (proteins)

What is X-Inactivation?

the inactivation of one X-chromosome in each cell during early embryonic development

Which gender has X-Inactivation?

only females

What happens with triple-x syndrome?

• three X-chromosomes

• Developmental delays

• Reduced fertility

Why do the triple-X syndrome symptoms happen?

because of extra proteins (chromosomes)

What happens with Klinefelter’s Syndrome?

• 2 X + 1 y chromosomes (XXy)

• reduced testes, less body hair

• breast development

Who does Klinefelter’s syndrome happen to?

Only males

What happens with Turner syndrome?

• 1 X-chromosome

• reduced stature

• developmental delays

• sterility

What are the two types of chromosomal structural rearrangements?

Inversion and Translocation

What is chromosome inversion?

a segment of genetic material detaches, rotates 180 degrees and reinserts

What are the two types of chromosome inversion?

Pericentric and Paracentric

What does Pericentric inversion include?

Includes the centromere

What does paracentric inversion include?

Does not include the centromere, just the arm

What happens during translocation?

segment of genetic material breaks off one chromosome and reattaches to another chromosome or a different region of the same one

What is reciprocal translocation?

exchange between nonhomologous chromosomes

What does reciprocal translocation result in?

No loss or gain of genetic information

What is nonreciprocal translocation?

transfer of chromosomal segment to nonhomologous chromosome

what does nonreciprocal translation result in?

loss or gain of genetic information depending on which one is losing/receiving

What negative effects can happen from translocation?

schizophrenia and some cancers