Question

part 3 - overview of meiosis
meiosis i
meiosis ii
____ pair up and separate.
____ separate.
crossing over and independent assortment occur.
no dna replication before this stage.
____ haploid cells are formed.
____ unique gametes are produced.
how many cells form at the end of meiosis, and are they haploid or diploid?
____
part 4 - karyotype practice
1 what is a karyotype used for? ____
2 how can you tell the sex of an individual from a karyotype? ____
3 what does \trisomy 21\ mean? ____
4 name one disorder caused by nondisjunction of sex chromosomes: ____
____
reflection
how do meiosis and fertilization work together to maintain chromosome number while creating unique individuals?

Explanation:

Meiosis is a type of cell division that reduces the chromosome number by half. In Meiosis I, homologous chromosomes pair up and separate. At the end of Meiosis I, two haploid cells are formed. In Meiosis II, sister chromatids separate, and four unique haploid gametes are produced.

A karyotype is a visual display of an individual's chromosomes. It is used to identify chromosomal abnormalities. The sex of an individual can be determined from a karyotype by looking at the sex chromosomes (XX for female, XY for male). Trisomy 21 means there are three copies of chromosome 21 (instead of the usual two), which causes Down syndrome. One disorder caused by nondisjunction of sex chromosomes is Klinefelter syndrome (XXY).

Meiosis reduces the chromosome number by half (producing haploid gametes), and fertilization (fusion of haploid gametes) restores the diploid chromosome number. Crossing over and independent assortment in meiosis create genetic variation, leading to unique individuals.

Answer:

• Meiosis I: Homologous chromosomes pair up and separate. Two haploid cells are formed.
• Meiosis II: Sister chromatids separate. Four unique gametes are produced.
• Number of cells at the end of meiosis: Four. They are haploid.
• Karyotype use: To identify chromosomal abnormalities.
• Sex from karyotype: By looking at sex chromosomes (XX - female, XY - male).
• Trisomy 21: Three copies of chromosome 21 (Down syndrome).
• Disorder from sex chromosome nondisjunction: Klinefelter syndrome (XXY).
• Meiosis and fertilization: Meiosis makes haploid gametes (reduces chromosome number), fertilization fuses gametes (restores diploid number). Meiosis creates variation (crossing over, independent assortment) for unique individuals.