Honours Biology: Meosis

Haploid Cell

a cell with a single chromosome set.

Chiasma (Chiasmata)

The site of crossing over, it appears as an X-shaped region and is the place where 2 homologous nonsister chromatids attach to one another.

Crossing Over

the exchange of corresponding segments between nonsister chromatids of homologous chromosomes.

Tetrads

sets of four chromatids, with each pair of sister chromatids joined at their centromeres.

Diploid Organism

an organism that’s body cells contain pairs of homologous chromosomes.

Diploid Number

the total number of chromosomes.

Somatic Cell

A cell that has 46 chromosomes.

Homologous Chromosomes

Two chromosomes that have the same genes in the same order, can sometimes have variation, and are paired up.

Fertilization

The process in which the father’s sperm cell and the mother’s egg cell fuse.

Zygote

A fertilized egg that is the result of fertilization and has two sets of homologous chromosomes (is diploid).

Life Cycle

The sequence of stages leading from the adults of one generation to the adults of the next.

Chromosomal Translocation

The attachment of a chromosomal fragment to a nonhomologous chromosome.

Reciprocal Translocation

Segments of two nonhomologous chromosomes swap locations with each other.

Duplication

A segment of a chromosome is copied and inserted into the homologous chromosome

Inversion

A segment of a chromosome is removed and then reinserted “backward” to its original orientation

Deletion

A segment of a chromosome is removed and is most likely to cause serious health problems.

ex: cri du chat

Polyploid Organism

An organism that has more than two sets of homologous chromosomes in each somatic cell.

ex: wheat, potatoes, apples, cotton, fish, and amphibians

X0- a female missing an x chromosome

Turner Syndrome.

XYY

Normal male, BUT will be significantly taller.

XXX

normal female.

XXY

Klinefelter Syndrome, and it’s when nondisjunction occurs in the egg or sperm formation and has a 1/2000 frequency.

Nondisjuntion

When there is a misshape in which the members of a chromosome pair fail to separate.

Trisomy 21

aka Down Syndrome- results of an extra 21st chromosome.

Lymphoctyes

A type of white blood cell used by medical scientists to prepare a karyotype.

Locus

The name for a specific part/band on a chromosome.

Karyotype

An ordered display of magnified images of an individual’s chromosomes arranged in pairs, it shows the chromosomes condensed and doubled.

Autosomes

The 22 pairs of chromosomes in males and females. (not including sex cells)

Gametes

The name used to collectively refer to egg and sperm cells.