Gamete Formation and Errors in Meiosis Flashcards
What is meiosis
The process where sex cells are produced (haploid) and typically there are 4 daughter cells
Spermatogenesis
The process of sperm production in testes
Oogenesis
the process of ova (egg) formation in the ovaries
What are the parent cells called during spermatogenesis
spermatogonia
What are the parent cells called during oogonium
What is the end product of spermiogenesis
4 haploid gametes (sperm)
What is the end product of oogenesis
One haploid gamete (ovum)
Why is only one ovum/egg produced?
This is because of the uneven division of cytoplasm during cell division. Polar bodies are the smaller parts of the cytoplasm failing to become a daughter cell as they will degenerate only leaving one ovum.
What methods help achieve genetic variation
Independent assortment and crossing over
Independent assortment
Metaphase- homologous pairs lined up on equator. In each pair, the maternal and paternal chromosomes will be pulled to different poles of the cell
Crossing over
while homologous chromosomes are lined up during prophase 1, non-sister chromatids of homologous pairs may exchange pieces of chromosomes
What are the two types of chromosomal error(mutations) that can occur during meiosis
1.changes in chromosome structure
2.changes in chromosome number
Changes in chromosome structure
Can happen from crossing over. The chemical bonds that hold the DNA together are broken, and may not reform correctly.
Deletion
a piece of a chromosome is deleted
Duplication
a section of a chromosome appears two or more times in a row
Inversion
a section of a chromosome is inverted
Translocation
a segment of one chromosome becomes attached to a different chromosome
What genetic disorder is caused by deletion
Cri du Chat (deletion of chromosome 5)
what genetic disorder is caused by duplication
Charcot-Marie-Tooth disease (duplication of chromosome 17)
what genetic disorder is caused by inversion
FG syndrome (inversion of a section of the X chromosome) - mostly in males
what genetic disorder is cause by translocation
Chronic Myelogenous Leukemia (translocation between chromosomes 9-22)
Non-disjunction
when homologous chromosomes or sister chromatid do not sperate as they should. Typically occurs in anaphase 1 or 2
Monosomy
a condition in which one chromosome is lost due to non-disjunction
Trisomy
a condition where there is a gain of an extra chromosome due to non-disjunction
What syndrome is trisomy 21
Down syndrome
What syndrome is trisomy 18
Edward syndrome
What syndrome is trisomy 13
Patau syndrome
What syndrome is XXY
Klinefelter syndrome
