Mitosis Vs. Meiosis
In humans, the end result is(are) cells with 23 single-stranded chromosomes, what is the process?
the process is meiosis
Is Mitosis sexual or asexual reproduction?
Mitosis is asexual reproduction.
How many times does Meiosis divide?
Mitosis goes through 2 rounds of division
What is the longest phase in the cell cycle?
The longest phase in the cell cycle is interphase.
What is a centromere?
A centromere is a structure that holds 2 chromatids together
What process of cell reproduction is used for asexual reproduction?
The process is mitosis
The product of Mitosis. How many chromosomes did the cells start with before they went through the cell cycle, in humans?
2 identical diploid cells. It started with 46 chromosomes.
The product of Meiosis. And how many chromosomes are within each one, for humans?
4 unique haploid cells that have 23 chromosomes each.
What are the 3 main steps in the cell cycle?
Interphase
Mitosis/meiosis
Cytokinesis
What forms spindle fibers during prophase?
Centrioles form spindle fibers
Describe why crossing over does not happen in a.) mitosis or b.) meiosis.
Crossing over does not happen in mitosis. This is because Mitosis produces 2 daughter cells that are identical to each other and the parent cell so if crossing over happened they would not be identical.
Name the four phases of mitosis in a cell.
Prophase
Metaphase
Anaphase
telophase
What is a haploid cell? Outline their uses in animals.
A haploid cell is a cell that has half the number of chromosomes as a somatic cell. In animals, haploid cells are the gametes ( eggs, sperm) and they are used in sexual reproduction because they only have half of the genetic material so it is able to fuse with the other gamete.
Outline the G0 phase.
The G0 phase is a resting phase for cells that exit the G1 phase. It can also be a permanent state for cells such as nerves cells. When a cell is in the G0 phase it means that the cell is not actively trying to divide and instead is just doing its job.
Difference between a chromatin and a chromosome.
Chromatins are loosely coiled whereas chromosomes are more tightly wrapped therefore have a more distinct shape.
How are the purposes of mitosis and meiosis different?
The purpose of mitosis is for cell regeneration and asexual reproduction whereas meiosis is used for the production of gametes for sexual reproduction.
Name and outline the process after Mitosis is completed.
The process is called cytokinesis. Cytokinesis is the division of materials outside of the nucleus. It divides the materials into roughly 2 halves.
Outline why can cells produced from meiosis not go through division/asexual reproduction.
Cells that are produced from meiosis can not go through division/asexual reproduction because they only have half of the genetic material, so they can not go through mitosis as they do not have the full DNA requirement.
Outline what happens in each of the stages of interphase.
In G1 the cells increase in size because the cells produce more ATP. In the S phase, the DNA is replicated. In G2 more enzymes and proteins that are used in Mitosis and Meiosis are produced, as well as final checks of the DNA are made to make sure the DNA was replicated properly.
Why is variation important?
If there is no genetic variation it leaves a species at risk of being wiped out. This is because genetic variation allows for a species' fitness because changing environments and what species are exposed to will not affect every individual the same allowing for better survival rates.
State and explain the difference between mitosis and meiosis.
The difference between mitosis and meiosis is that mitosis produces 2 exact replicas of the parent cell with the same amount of chromosomes whereas meiosis produces 4 genetically different cells with half the number of chromosomes than the parent.
Explain why homologous chromosomes do not pair up in mitosis.
Homologous chromosomes do not pair up in mitosis because the aim of mitosis is to create genetically identical cells, and if the homologous chromosomes are paired up, crossing over will occur. If crossing over occurs, then the daughter cells produced will not be genetically identical to each other.
Where does variation occur, give 2 examples and explain how it leads to variation.
In prophase 1 when crossing over between the homologous pairs of chromosomes from the parents switch genes. This creates variation because now each chromosome can have characteristics from both parents instead of only containing one. In metaphase 1, the 2 pairs of homologous chromosomes randomly align along the cell's equator before it splits. This gives variation because when the cell splits in half it can have chromosomes from both parents because it is not an even split where one parent's genetic information goes to one side.
Why are checkpoints during the cell cycle important?
Checkpoints throughout the cell are important because the checkpoints are there to identify if there are mutations in the cell or if the cell has not been developed as much as it should have ( short of nutrients and if DNA was not replicated) If there were no checkpoints then cells would be able to divide and may produce damaged cells that would harm the individual. An example would be a cancer mutation.
Explain why you can see chromosomes more clearly than chromatins when dye is added.
This is because chromosomes are more tightly coiled. Therefore when dyed it is clearer to see because it has a clear shape. Whereas chromatins are more loosely coiled so there is no defined shape, so even when dyed it is difficult to see.