Mitosis and meisos Watch

mistel
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Can some one explain to me both processes in a SIMPLE form yet including A grade content , I don't understand all this chromosome stuff and pairing etc.

I do understand the dna zipping part from the mitosis process though.

Thanks in advance
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go-study-hard
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Which exam board is this for, and what level, AS or A-Level?
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MarkProbio
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Indeed, let us know what level you're studying at.

As a basis, do you understand that each body cell has two of each chromosome: one from mum, one from dad?

This is vital in understanding mitosis and meiosis. I'd worry about mitosis first. Meiosis is similar but with a few extra (important) details.

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mistel
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(Original post by MarkProbio)
Indeed, let us know what level you're studying at.

As a basis, do you understand that each body cell has two of each chromosome: one from mum, one from dad?

This is vital in understanding mitosis and meiosis. I'd worry about mitosis first. Meiosis is similar but with a few extra (important) details.

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I'm doing gcse ocr gateway science B , I understand each chromosome is a pair and that half DNA from each parent
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MarkProbio
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(Original post by mistel)
I'm doing gcse ocr gateway science B , I understand each chromosome is a pair and that half DNA from each parent
Okay so have you any idea of the different phases of mitosis? To summarise:

1. Each chromosome replicates in S-Phase (before mitosis) so each cell has 96 chromosomes. The copies are called "sister chromatids" to the originals and are joined by a centromere.

2. Prophase is when the chromosomes supercoil, so we can view them under a microscope, and the nuclear envelope breaks down. Centrioles separate to opposite poles of the cell - these are what create spindle fibre to pull the sister chromatids.

3. Metaphase is when the chromosomes line up along the equator of the cell and attach to spindle created by the centrioles.

4. Anaphase is when the spindle fibres contract (shorten) and each sister chromatid is pulled to opposite poles of the cell. The centromere breaks in the process.

5. Telophase is when the cell begins to cleave into two daughter cells that are genetically identical to the original. The nuclear envelope reforms and the spindle fibres break down.

The process where the two new cells form is not actually mitosis but a process called cytokinesis shortly after telophase.

This is just mitosis, but learn this before meiosis. Remember: PMAT for the order of the phases.

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LilyZo
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Go onto YouTube and search 'Crash Course Meosis' and 'Crash Course Mitosis', absolutely brilliant visual explanation


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mistel
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I still don't get it all I need is a gcse explanation thankyou
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MarkProbio
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Mitosis produces two genetically identical body cells. They have two sets of chromosomes.

Meiosis produces four genetically different sex cells (sperm, egg and plant gametes) that are haploid - they have only one set of chromosomes.
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mistel
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(Original post by MarkProbio)
Mitosis produces two genetically identical body cells. They have two sets of chromosomes.

Meiosis produces four genetically different sex cells (sperm, egg and plant gametes) that are haploid - they have only one set of chromosomes.
Can you explain diploid and haploid please and other keywords involves In mitosis / meiosis. Thanks!
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MarkProbio
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(Original post by mistel)
Can you explain diploid and haploid please and other keywords involves In mitosis / meiosis. Thanks!
The diploid number of chromosomes is two sets of chromosomes - one set from mum, one set from dad. This is 46 in humans (23x2) and occurs in body cells eg skin cells, nerve cells. It's referred to as 2n.

Haploid is one set of chromosomes, this occurs in sex cells (gametes) such as sperm and egg in animals. When two sex cells combine in fertilisation the diploid number is restored. You can remember haploid as being half the number as haploid/half both begin with "ha".

Any other terms?

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mistel
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What do you mean as sets?
Do you mean pairs?
And for the gametes when you say single set do you mean a single set of two choromosomes or just one individual chromosome?

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MarkProbio
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(Original post by mistel)
What do you mean as sets?
Do you mean pairs?
And for the gametes when you say single set do you mean a single set of two choromosomes or just one individual chromosome?

Thanks
Each human body cell has 46 chromosomes, 23 from mum, 23 from dad. Gametes only have 23, so this is what I mean by sets.

When the gametes fuse in fertilisation, the body cell number of 46 is restored. There should be plenty of good pics online to explain it in a more visual manner.

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L'Evil Fish
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(Original post by MarkProbio)
Okay so have you any idea of the different phases of mitosis? To summarise:

1. Each chromosome replicates in S-Phase (before mitosis) so each cell has 96 chromosomes. The copies are called "sister chromatids" to the originals and are joined by a centromere.

2. Prophase is when the chromosomes supercoil, so we can view them under a microscope, and the nuclear envelope breaks down. Centrioles separate to opposite poles of the cell - these are what create spindle fibre to pull the sister chromatids.

3. Metaphase is when the chromosomes line up along the equator of the cell and attach to spindle created by the centrioles.

4. Anaphase is when the spindle fibres contract (shorten) and each sister chromatid is pulled to opposite poles of the cell. The centromere breaks in the process.

5. Telophase is when the cell begins to cleave into two daughter cells that are genetically identical to the original. The nuclear envelope reforms and the spindle fibres break down.

The process where the two new cells form is not actually mitosis but a process called cytokinesis shortly after telophase.

This is just mitosis, but learn this before meiosis. Remember: PMAT for the order of the phases.

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:lol: this is AS ish. GCSE is a lot simpler.
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courtnibro
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Asexual reproduction is mitosis. Sexual reproduction is meiosis


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