Unit 6: Meiosis

Haploid

23 chromosomes in humans Found only in gametes (sperm and egg)

What is the end result of meiosis?

4 haploid cells that are different

Diploid

46 chromosomes in humans Found in most somatic cells

Metaphase 1

Homologous chromosomes line up in center

What is crossing over and when does it occur?

Homologous chromosomes overlap and exchange genetic material, occurs in Prophase 1

Anaphase 1

Homologous chromosomes pulled to opposite ends of the cell

Anaphase 2

Sister chromatids pulled to opposite ends of the cell

Prophase 2

chromosomes condense

Autosomes

chromosomes other than the sex chromosomes. The first 22 pairs of the karyotype.

Klinefelter syndrome

extra X chromosome in males

What is a zygote?

fertilized egg cell

what is a section of DNA that codes for a trait?

gene

Turner Syndrome

monosomy X, One X chromosome in females

Where does meiosis occur?

ovaries and testes

Prophase 1

Chromosomes condense, crossing-over occurs

Metaphase 2

Chromosomes line up in the middle

homologous chromosomes

Chromosomes which carry the same traits/genes as another

What is nondisjunction?

Failure for chromosomes to separate properly.

What is another name for downs syndrome? What is is?

Trisomy 21, an extra chromosome 21

Telophase 1

Two separate nuclei form (haploid cells)

Telophase 2

Two separate nuclei form (haploid cells) (So now 4 cells)

sex chromosomes

X and Y in humans. The last pair of chromosomes in the karyotype.

What is a karyotype?

a photomicrograph of chromosomes in a dividing cell