Chapter 13 Pt 2 Flashcards
Stages of meiosis
Prophase
Metaphase
Anaphase
Telophase (cytokinesis)
What is synapsis
Paired homologous chromosomes are attached to each other by a protein complex (synaptonemal complex) that runs along their length
-homologous chromosomes are aligned gene by gene
What is crossing over?
Corresponding segments of DNA is traded between non sister chromatids
Early prophase 1
Chromosomes begin to condense
Synapsis
Crossing over
Later in prophase 1
- synaptonemal complex dissolves; homologous chromosomes move are still attached at where the crossing over occurred by cohesion proteins
- mitotic spindle forms
- nuclear envelope breaks
Even later in prophase
- kinetochores are formed
- micro tubules attach to kinetochores
Metaphase
Homologous chromosomes line up along the metaphase plate
Anaphase
Homologous chromosomes are separated (sister chromatids remain connected)
Telophase
- homologs complete their migration to the poles
- spindle is disassembled
- chromosomes may deco dense
- nuclear membrane my re form
Cytokinesis
Division of the cytoplasm occurs simultaneously with telophase
Independent assortment
Refers to the random orientation of homologous chromosomes during metaphase 1 of meiosis
-2^n possible gamete combinations
What does meiosis produce?
Produces 4 haploid daughter cells from one diploid parent cell
What does crossing over produce?
Recombinant chromosomes
Recombinant chromosomes
Contain DNA from 2 different parents
Random fertilization
Gametes randomly combine at fertilization
-the number of diff possible combinations is the product of the number of different possible gametes in the mother times those in the father
2^23 x 2^23 = ~70 trillion possible zygotes
