Nondisjunction and Karyotype Review

Front

What is nondisjunction?

Back

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to gametes with an abnormal number of chromosomes.

Front

What are sister chromatids?

Back

Sister chromatids are identical copies of a chromosome, connected by a centromere, that are formed during DNA replication.

Front

What are homologous chromosomes?

Back

Homologous chromosomes are pairs of chromosomes, one inherited from each parent, that have the same genes at the same loci but may have different alleles.

Front

What is a karyotype?

Back

A karyotype is a visual representation of an individual's chromosomes, arranged in pairs and organized by size and shape.

Front

What is the probability of a typical gamete resulting from nondisjunction in metaphase I?

Back

0%.

Front

What is the probability of a typical gamete resulting from nondisjunction in metaphase II?

Back

50%.

Front

What occurs during anaphase of mitosis?

Back

During anaphase of mitosis, sister chromatids are pulled apart to opposite poles of the cell.

Front

What is the main difference between meiosis I and meiosis II?

Back

In meiosis I, homologous chromosomes separate, while in meiosis II, sister chromatids separate.

Front

What is crossing over?

Back

Crossing over is the exchange of genetic material between homologous chromosomes during prophase I of meiosis, leading to genetic variation.

Front

What are autosomes?

Back

Autosomes are chromosomes that are not involved in determining the sex of an individual; humans have 22 pairs of autosomes.