Unit #7: Meiosis Flashcards
Define genetics
Study of heredity and heredity variation
Define heredity
The generational passing of traits.
What is a locus?
A specific gene location on a chromosome
What is a homologous pair?
2 chromosomes of similar size and shape carrying the same genes.
What are some diplontic organisms and what makes them diplontic?
Humans, other animals, because we spend most of our lives as diploids and are only haploid when we are gametes.
What are some haplontic organisms and what makes them haplontic?
Fungi and protists, most of the time are haploid, only diploid when fertilized.
What are some diplontic organisms and what makes them diplontic?
Plants, because half their life they are diploid and half they are haploid.
What is the goal of Meiosis?
To reduce ploidy (diploid to haploid)
In G1, chromosomes have one chromatid, after DNA duplication, they have…
2!
What is a tetrad?
A pair of aligned homologous chromosomes.
In meiosis, we start with 1 diploid cell, we end with…
4 haploid cells.
What occurs in Prophase 1?
Chromosomes condense, tetrads come together and crossing over occurs.
What occurs in Metaphase 1?
Tetrads line up at the equator, spindle fibers attach to either side of the tetrad (1 per chromosome).
What occurs in Anaphase 1?
Spindle fibers shorten and the tetrad is pulled apart.
What occurs in Telophase 1?
Homologues are at opposite poles, chromosomes uncondense and cytokinesis occurs.
Is meiosis II the same as mitosis?
Yes except is happens 2x per one original diploid cell.
When is ploidy reduction complete in meiosis?
Anaphase 1
What is crossing over?
When sister chromatids get super close, and pieces of the chromatids snap off and reattach to the other.
What is a chiasmata?
The site where crossing over occurs.
What is independent assortment?
Tetrads align randomly and independently in Metaphase 1, meaning that which chromatid goes to which chromosome is independent of the others.
What is random fertilization?
The fact that there are 2^23 possible gametes that can be passed on per ova and sperm, therefore, which egg gets fertilized is random.
