Meiosis Flashcards
Somatic cells have ___ sets of chromosomes.
Two
Gametes have ____ as many chromsomes as somatic cells.
Half
Ovaries and testes produce _____ gametes by meiosis.
Haploid
What is fertilization?
Union of gametes (sperm and egg)
What is a zygote?
Fetilized egg- 1 set of chromosomes from each parent, 2 sets total, divides by mitosis
True or false, meiosis undergoes replication of chromosomes
True
What is the end result of meiosis? How many cells are in the product?
Haploid number of chromsomes (4 cells)
What occurs in Meiosis 1?
Seperation of homologous chromosomes
What occurs in Meiosis 2?
Seperation of sister chromatids
What are the stages of Meiosis 1?
- Prophase 1
- Metaphase 1
- Anaphase 1
- Telophase 1 and cytokinesis
What occurs in prophase 1?
Condensation of chromatids
What occurs in metaphase 1?
Homologs line up in the middle along the metaphase plate
What occurs in anaphase 1?
Sepertation of homologous pairs
What occurs in telophase 1 and cytokinesis?
Nucleous reforms and the cytoplasm pinches off
What is crossing over? Where does it occur?
- Exchange of genetic material
2. Prophase 1
What is the chiasmata?
X-shaped regions, sites of crossovers
What is recombinant chromosomes?
Combined DNA from each parent (genetic variation) Product of crossing over
What is the synapsis?
Fusion of chromosomes (covalent bonds)
What is the synaptonemal complex?
Area where the chromsomes combine and are held together
What attaches to each chromosome in metaphase 1?
Kinetochore microtubules
What is independent assortment of chromosomes?
Each homologous pair assort themselves during this phase (order does not matter)
What is the result of independent assortment?
Different chromsomes in meiosis 2
What is the equation for the number of possible combos in independent assortment?
2^n
What is the major difference between anaphase 1 and regular anaphase in mitosis?
Sister chromatids remain attached at centromere and move as one unit toward pole
Are cells haploid or diploid after meiosis 1?
Haploid
True or false… DNA replication occurs after telophase 1 and before the start of meiosis 2.
FALSE
What occurs is in meiosis 2?
Separation of sister chromatids
When does the nuclear envelope break down in meiosis?
Prophase
What makes sister chromatids not 100% identical?
Crossing over
Name three unique events that are only in meiosis 1…
- Synapsis and crossing over
- Independent assortment
- Separation of homologs
* * no official prometaphase
KNOW THE DIFFERENCES IN MITOSIS AND MEIOSIS
OKIE DOKIE
What are the three factors that contribute to genetic variation?
- Independent assortment (metaphase 1)
- Crossing over (prophase 1)
- Random fertilization
