Mitosis and Meiosis Flashcards
What’s the difference with diploid and haploid cells?
Diploid: 2 sets of chromosomes (one from dad and one from mom)
Haploid: 1 set of chromosome (gametes/sex cells where you need only one set of chromosomes (23 chromosomes in total) so that when the sperm combines with the egg, it can form a diploid cell of 46 chromosomes
What does it mean when they say a diploid cell with 5 chromosome pairs , how many centromeres will be found at G2 phase of cell division cycle?
Diploid cell of 5 chromosome pairs mean that there are 5 chromosome from dad and 5 chromosomes from mom.
After they have been duplicated in S phase and form sister chromatids, in G2 phase, there would still be 10 chromosomes but each that have their own sister chromatid. Hence, if there are 10 chromosomes then there are 10 centromeres.
What are homologous chromosomes?
YK how chromosomes are just like pieces of the different parts of the whole genome?
Well so homologous chromosomes just consists of 1 chromosome from the mom and 1 chromosome from the dad in a diploid cell. However, those chromosomes code for the same thing for example, eyes.
However, they could vary from each other through alleles of the same gene like the father’s chromosome codes for green eyes while the mom codes for brown.
You can observe homologous chromosomes through a karyotype. The chromosomes should have the same banding, same length, and same loci of genes.
What happens to homologous chromosomes in the full cell cycle and mitosis?
Well throughout mitosis and even the cell cycle, somatic cells already have 46 chromosomes where 23 is from each parent. Hence there are already homologous chromosomes.
Even after/during the S phase, each individual chromosome is duplicated and each chromosome will now have sister chromatids. However, homologous chromosomes still exist just now, each of the homologous chromosome pairs will have like chromosomes that look like an “X” instead of just a “I”.
What is siter chromatid cohesion?
This is the same in mitosis and meiosis where when chromosomes get duplicated, the sister chromatids are attached together.
What happens in meiosis 1 and 2?
Meiosis 1 is when the two chromosomes (don’t have sis chromatids yet) get duplicated and have sis chromatids. Then, each chromasome separates into two daughter cells.
In meiosis 2, those daughter cell split into 4 other daughter cells with each daughter cell having one sister chromatid instead of a “X” as they are now known as haploid cells with unduplicated chromosomes of “I”.
WHat happens in prophase I?
The homologous chromosomes pair up with each other and then crossing over happens.
Crossing over is when the non sis chromatids of the homologous chromosomes cross over each other to form a mini x shape. Then, they literally give part of them in exchange for a part of the other non sis chromatid.
the mini x is called a chiasmata
This is what causes genetic variation in gametes.
what happens in prophase of mitosis?
The centroiles start to form and the nuclear envelope starts to break down. Chromatin is still turning into chromosomes
What happens in metaphase 1 of meiosis?
homologous pairs line up in the center and microtubules attatch to them.
What happens in metaphase of mitosis?
so chromosomes line up at the plate of the cell (center) and mitotic spindles attatch to their kinetochores.
What happens in Anaphase 1 of meiosis?
homologous pairs separate to different poles however their sis chromatids remain attatched.
What happens in anaphase of mitosis?
sister chromatids of chromosomes are split apart as they are pulled to opposite poles through microtubules.
What happens in Telophase 1 and cytokinesis of meiosis?
There are now two daughter cells that are haploid where the chromosomes have two sister chromatids.
In animal cells, it forms a cleavage furrow while in plant cells, it forms a cell plate
what happens in telophase and cytokinesis of mitosis?
chromsomoes condense into chromatid and the cells are still diploid
