Similarities and Differences of Mitosis and Meiosis

General Differences:

Mitosis

1. Process of reproduction where the cell divides in half, producing a replica. The number of chromosomes equal in the new daughter cells.
2. Second stage of the cell cycle.
   
3. Mitosis has six steps (interphase, prophase, metaphase, anaphase, telophase, and cytokinesis).
4. In mitosis, the cell divides once, producing two daughter cells.
5. Mitosis occurs in all organisms.
6. During mitosis, there is no crossover of DNA.
7. Is able to produce any cell (e.g. skin cells, bone cells, blood cells, etc) except for sex cells (sperm cells and egg cells).
8. The purpose is of mitosis is to allow multi-cellular organisms to grow and also repair damaged tissue.
   

Meiosis

1. Process of reproduction where the number of chromosomes is split in half and sex cells are produced. This is because when two sex cells meet to produce an organism, each contributes their half of chromosomes, and the new organism has one full set of chromosomes.
2. Meiosis has nine steps (interphase, prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II).
3. In meiosis, the cell divides twice, producing four daughter cells.
4. Meiosis only occurs in animals, fungi, plants, and humans.
5. During meiosis, there is at least one cross over of DNA.
6. Only produces sex cells (sperm cells and egg cells).
7. The purpose of meiosis is to allow the reproduction of organisms to take place.
   

General Similarities:

• Both are processes of reproduction
  

Mitosis and Meiosis Stages: Differences and Similarities

Before Mitosis: Interphase

During interphase, the cell grows to its fullest size and creates duplicates structures the future daughter cells will need. This is because the cell reproduces two daughter cells, both will need the sufficient amount of organelles. The cell also makes its DNA. This process is called replication, and is very important because each daughter cell must have a complete set of DNA. In animal cells, cylindrical structures called centrioles are also duplicated

Before the cell has replicated DNA

After the cell has replicated DNA. The centrioles are also duplicated.

Before Meiosis

Before meiosis, the cell replicates its chromosomes so that each one has a pair. After this, the chromosomes go through a process called "crossing over". Crossing over is when genes are exchanged between the chromosomes. This creates new gene combinations and more genetic diversity.

Before the cell has replicated its chromosomes

After the cell has replicated its chromosomes

Crossing over!

Similarities and Differences

Similarities: During both phases, DNA is replicated. The DNA is also replicated for the same reasons, being that at the end of the process the extra set(s) of DNA will go to the daughter cells produced.

Differences: During meiosis, genes cross over to create new gene combinations. This does not occur in before mitosis. Also, during interphase (the stage before mitosis in the cell cycle), the cell grows to its fullest size and creates new structures for its future daughter cells.

Mitosis Phase 1: prophase

During prophase, the chromatin condenses, forming chromosomes. Each chromosome has two chromatids, which are exactly the same. These chromatids are held together by centromeres. The centrioles move to opposite ends of the cell, and spindle fibers develop in between them, creating a 'bridge'. The nuclear envelope and nucleolus (an organelle that produces ribosomes in the nucleus) break down.

The centrioles are moving to opposite ends of the cell, and the spindle fibers are forming a bridge between them. Soon, the cell membrane, nucleolus, and nuclear envelope will break down.

Meiosis 1A

The centrioles move to opposite ends of the cell, and spindle fibers develop in between them, creating a 'bridge'.

As one can see, this picture is identical to the picture representing prophase. The only thing this picture (which represents the difference between these two stages) is that the chromosomes should be crossed over.

Similarities and Differences

Similarities: During both phases, the centrioles move to opposite ends of the cell and spind fibers form between them creating a bridge. Also, the cell membrane, nucleolus, and nuclear envelope all break down.

Differences: One difference between these two phases is that during mitosis, the chromatid condense into chromosomes. This doesn't happen in Meiosis 1A because the genes in the cell during meiosis are already in chromsome form. Also, when the chromatid condenses into chromsomes, there is no crossing over.

Mitosis Phase 2: Metaphase

During metaphase, each chromosome lines up in the center of the cell. Each spindle fiber then connects to one of the chromosomes by its centromere.

All of the chromosomes are lined up in the center of the cell, and each spindle fiber has attached itself to the centromere of a chromosome.

Meiosis 1B

During meiosis 1B, chromosomes line up in the center of the cell, and the pairs facing each other. Then the spindle fibers attach themselves to the centromere of each chromsome.

The chromosome pairs are facing each other in the center of the cell and a spindle fiber is attached to every chromosome.

Similarities and Differences

Similarities: In both phases, the chromosomes have lined up in the center of the cell. Also, each spindle fiber has attached to each of the chromosomes by their centromere.

Differences: During metaphase, the all of the chromosomes line up in the center of the cell side by side. On the contrary, during meiosis 1B, the chromosome pairs are lined up in the center of the cell side by side, whereas the individual chromsomes face their pairs, creating two 'lines' of chromosomes.

Mitosis Phase 2: Anaphase

During anaphase, the centromeres (the part of the chromosome that holds the two chromatids together) split. This is caused by the spindle fibres, which are bringing one chromatid from each chromosome to opposite ends of the cell. The force of the opposite ends pushing apart results in the cell stretching.

Centromeres split from the force of the spindle fibers bringing the chromatids to opposite ends of the cell. The cell is also stretched out during this process.

Meiosis 1C

Assisted by the spindle fibers they are connected with, the chromosome pairs separate from each other and move to opposite ends of the cell. During this process, the cell is stretched because of the force the spindle fibers are exerting to bring the chromosomes to opposite ends of the cell.

Chromosome pairs are being taken away from each other, but centromeres do not split. The cell is also stretched out during this process.

Similarities and Differences

Similarities: During both processes, spindle fibers bring chromatid(s) to opposite ends of the cell. The force the fibers exert also cause the cell to stretch.

Differences: During anaphase, the centromeres split, and each spindle fiber only brings one chromatid to its end of the cell. During meiosis 1C, the centromeres do not split, but the chromosome pairs are separated from each other and brought to opposite ends of the cell, with each spindle fiber essentially bringing two chromatids to their end of the cell.

Mitosis Phase 3: Telophase

During telophase, the chromosomes start to stretch out. This causes them to lose their rod-like shape. A new nuclear envelope forms around the two chromosome areas. This is the last stage of mitosis. After telophase come the third and final stage of the cell cycle, called cytokinesis. During cytokinesis, the actual division of the cell occurs.

The new nuclear envelopes have formed around the two areas the chromosomes occupy, and the actual chromosomes do not look as rod-like anymore.

Meiosis 1D

During meiosis 1D, two new cells form. Each cell has half the amount of chromosomes as the original cell, but the chromosomes still have two chromatids. Nuclear envelopes reform in each cell.

The two cells have formed, each with a nuclear envelope. As one can see, the chromosomes each have two chromatids.

Similarities and Differences

Similarities: One similarity between these two phases is that nuclear envelopes form around each area the chromosomes occupy. Also, inside each nuclear envelope there is half of the amount of chromosomes that the original cells initially had.

Differences: A difference between these two phases is that during meiosis 1D, the cell actually forms two new cells. During telophase, the cell stretches out even more but does not form two new cells.

~There are no more phases in mitosis~

Meiosis 2A

During the 2nd section of meiosis, the chromosomes line up in the center of the cell. The spindle fibers attach to the chromosomes' centromeres.

As one can see, both cells are undergoing the same procedures.

Similarities and Differences

Similarities:  Evidently, this phase is almost exactly the same as the previous phase 1B in meiosis and metaphase in mitosis.

Differences: The main difference between this stage and mitosis is that mitosis does not have repeat its metaphase because meiosis is a lengthier process than mitosis. During meiosis, four cells are produced, while in mitosis, only two cells are produced. This means that there is no need for mitosis to repeat it's previous steps, which is what happens during meiosis.

~There are no more phases in mitosis~

Meiosis 2B

During this phase, the centromeres of each chromosome split. Then the individual chromatids are pulled to opposite ends of the cell by the spindle fibers, simultaneously stretching out the cell.

Similarities and Differences

Similarities: This phase is almost identical to the previous stage 1C in meiosis, and even more similar to anaphase during mitosis!

Differences: This stage does not occur in mitosis.

~There are no more phases in mitosis~

Meiosis 3

Meiosis 3 is the fina phase of meiosis! During this phase, four sex cells are produced. Each cell has half of the number of chromosomes the original cell/ parent cell had. Also, each new cell has only one chromosome from each original pair the parent cell had.

Similarities and Differences

Similarities: During both ending phases of mitosis and meiosis, the nuclear envelopes each contain half of the amount of chromosomes the original parent cell had.

Differences: A difference between Meiosis 3 and mitosis is that during mitosis, the actual forming of the daughter cells does not occur, and everything the phases of mitosis build up to stays in one cell.