Meiosis Flashcards
(20 cards)
What is Meiosis?
The process of creating haploid cells that are known as gametes, that are used in sexual reproduction.
What are the two main phases of Meiosis?
Meiosis I and Meiosis II.
What is sexual reproduction?
The combination of two different gametes to make a new organism.
What is asexual reproduction?
The process of creating a genetically identical offspring, otherwise known as a clone.
Which stages occur during Meiosis I
Long Prophase, Metaphase I, Anaphase I, and Telophase I.
What parts make up Long Prophase (Prophase I)?
Early, Middle, and Late prophases.
What happens during early prophase?
The chromatin condenses after interphase.
What happens during middle prophase?
Synapsis occurs in this part.
What is synapsis?
It is the process in which two homologous pairs of chromosomes connect and adhere to each other along the entire length of their chromosomes.
What happens during late prophase?
After the homologous pairs fuse, chiasmata form and crossing over occurs. The end product is 4 recombinant chromatids.
What are chiasmata?
Bridges that form between two homologs, where random sections of DNA are exchanged.
What is crossing over?
It is one of the processes of increasing genetic diversity. Two homologs connect with chiasmata and solve the cohesion problem by exchanging random sections of each chromatid. This forms recombinant chromatids.
What are recombinant chromatids?
Chromatids that have exchanged genetic information within their homologous pair.
What occurs during Metaphase I?
The process is the same as mitosis, except homologous pairs are separated, but sister chromatids are not. The chromosomes are also randomly lined up and taken to either cell (the same number of chromosomes go to each dipole).
What happens during Anaphase I?
This process of separation is the same as mitosis, but independent assortment has occurred, so the diversity of gametes is even greater.
How does Independent Assortment increase genetic diversity?
It has 2^n combinations, n being the number of types of chromosomes. It makes it so that there are over 8 million different combinations.
What happens during Meiosis II?
Prophase II, Metaphase II, Anaphase II, and Telophase II.
What functions are the similarities and differences in the sub- processes of Meiosis I in Meiosis II?
Prophase II - Chromosomes condense, but DNA does not replicate
Metaphase II - Same as metaphase I
Anaphase II - Chromatid finally separate, but due to crossing over, each cell has a different genetic makeup.
What happens in Telophase II and what are the products?
Cell division occurs again, turning diploid cells into haploid cells, each with their own nuclei. This produces 4 cells that are ready to be packaged into gametes and used in sexual reproduction.
What is disjunction?
An error in division during meiosis that causes a genetic abnormality. This often leads to unsuccessful offspring that cannot reproduce and typically have other physical or mental disadvantages or disorders.
