Bio chapter 9 Meiosis Flashcards
Meiosis
Produces gametes. Four daughter cells which are haploid are produced from a single precursor cell. Chromosome number is reduced in half. Two chromosomal replications. Happens only in germ cells.
Meiosis I
Reductive division, PMAT I and cytokinesis
Prophase I
Homologous chromosomes align to their genes match up. Crossing over occurs. Synapsis or pairing of homologous chromosomes.
Linkage
The tendency of genes on the same chromosome to stay together in the same gamete.
Chiasmata
Evidence of crossover. Area shaped like an X. Homologous non sister chromatids exchanged their genetic material.
Synaptonemal complex
Maintains the synapsis process in a fixed state until crossing over occurs. It is a protein that provides structural framework for crossing over to occur during Prophase I.
Metaphase I
Synaptic pairs line up, microtubules are attached to the kinetochore.
Anaphase I
Each pair of homologous chromosomes separate. No longer sister chromatids but separation homologues.
Telophase I and cytokinesis
Two haploid cells form, two chromatid sister still make up a chromosome.
Meiosis II
Similar to mitosis. Spindle apparatus forms to separate the two sister chromatids.
Metaphase II
Double stranded chromosomes become attached to the spindle, each chromosome is aligned at spindle equator.
Anaphase II
Each chromosome splits; sister chromatids are now on their own and migrate to opposite poles.
Telophase II and cytokinesis
Four daughter nuclei; after cytokinesis each gamete has a haploid number of chromosomes.
Mitosis vs Meiosis production
Mitosis produces clones- 2 daughter cells
Meiosis produces variation- only occurs in germ cells.
Compare mitosis vs meiosis in synapsis and crossing over
Mitosis: no synapsis and no crossing over
Meiosis: Synapsis occurs and crossing over in prophase I
Mitosis vs meiosis purpose
Mitosis: produces cells for growth and repair
Meiosis: produces gametes
Chromosomes are photographed when most condensed in ____ for a karyotype
Metaphase
Fertilization is also called __ ( Mitosis).
Syngamy
Mitotic Phase Chromosome # vs Chromatid #
Through PMAT, chromatid # is always 92. From metaphase to anaphase chromosome # changes from 46 to 92.
Meiosis I Chromosome # vs Chromatid #
PMAT I Chromosome #3 and chromatid # stays the same at 46 and 92. After End of Meiosis I then chromosome and chromatid # is divided by 2.
Meiosis II
Chromatid # is 46 until end of Meiosis II, 23. Chromosome # changes Metaphase II 23 to anaphase 46 and halves at the end of meiosis II.
Spermatogenesis
Seminiferous tubules of testes. Continuously be made. Meiosis and differentiation to yield 4 mature spermatozoa. LH and FSH work together.
Primary spermatocyte vs secondary spermatocytes and spermatids
Primary 2N, Secondary and spermatids N.
Sperm
Head of sperm is the acrosome. It contains hyaluronidase which breaks down the zone pellucida (outer membrane of ova), allowing for syngamy (fertilization).
