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
