Chapter 11 review

What is Down Syndrome caused by?

It is a condition caused by having too many copies of a chromosome, specifically an extra copy of chromosome 21.

What are the key characteristics of Down Syndrome?

Short stature, distinct facial features, mild to moderate physical and cognitive impairment, and increased risk of various health problems.

What is the most common form of Down Syndrome?

Trisomy 21, which accounts for 95% of all cases.

How many chromosomes do humans have?

Humans have 46 total chromosomes, making them diploid (2n).

What process allows diploid organisms to produce gametes?

Meiosis, which is a special type of cell division.

What happens during crossing over in meiosis?

Genetic recombination occurs, allowing homologous chromosomes to exchange equivalent sections.

What is nondisjunction?

The failure of chromosomes to move to opposite poles during meiosis, leading to gametes with missing or extra chromosomes.

What is karyotyping?

A process used to detect Down Syndrome by isolating chromosomes during fetal cell division and arranging them in pairs.

How does meiosis differ from mitosis in terms of chromosomal behavior?

In meiosis, homologous chromosomes pair and undergo crossing over, while in mitosis, homologues do not pair.

What is the role of the centromere during cell division?

The centromere is the point of constriction that holds sister chromatids together until they are separated during anaphase.