Mitosis and Meiosis and Sexual Reproduction in Plants/Animals

Meiosis I vs Meiosis II vs Mitosis

1.) Mitosis 2n to 2n

Meiosis I 2n to 1n

Meiosis II 1n to 1n

In meiosis I, homologous chromosomes separate, resulting in two haploid daughter cells with replicated chromosomes. In meiosis II, sister chromatids separate, resulting in four haploid daughter cells with replicated chromosomes.

synapsis

the pairing of homologous chromosomes during meiosis

crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Cohesion, separase, and shugoshin in meiosis and mitosis

cohesion holds the sister chromatids together. In anaphase, one homologous chromosome is on one side and one on the other. To be able to pull them apart, separase comes and degrades cohesion proteins holding them together. They can be pulled apart. Shugoshin wraps around the cohesions between them to protect those.

Prophase I

The chromosomes condense, and the nuclear envelope breaks down. crossing-over occurs.

Metaphase I (Meiosis)

Tetrads are lined up at the metaphase plate; Spindle fibers attach

Anaphase I (Meiosis)

Homologous chromosomes line up along the metaphase plate on opposite sides so that they can be split by the spindle fibers.

Telophase I

The cytoplasm divides in the cell, new membranes form to generate new cells.

homologous chromosomes

Pair of chromosomes that are the same size, same appearance and same genes.

nonhomologous chromosomes

chromosomes that do not match because they have different sets of genes

isogamous

gametes that appear the same size

heterogamous

gametes unlike in size

Spermatogenesis

Formation of sperm - genetically diverse haploid sperm, divided continually after puberty

Oogenesis

the production, growth, and maturation of an egg, or ovum - all made at birth.

Microsporocyte vs Megasporocyte, what does it form

micro - male sperm, mega - female ovum, forms a zygote, and then through mitosis a plant

What do the three haploid nuclei from the microsporocyte do?

2 will fertilize, while one will join the megasporocyte egg to form. the 2n nucleus embryo.

double fertilization

The embryo with a haploid nuclei from mom and dad is the first, and then the second fertilization with 2 haploid nuclei from sperm and 1 haploid from egg = triploid nucleus