- Contains the "instructions" to put an organism together and make it work.
- It's found in the nucleus of and animal and plant cells.
- It's comes in really long molecules called chromosome.
- A gene is a section of DNA.
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Mitosis is asexual cell reproduction
- Body cells normally have two copies of each chromosome, however with mitosis they don't.
- When a body cell divides it needs to make new cells identical to the original cell.
- This type of cell division is called mitosis.
Process of mitosis:
- In a cell that's not dividing the DNA is in long strings.
- If the cell is going to divide it duplicates its DNA to form x-shaped chromosomes.
- The chromosomes then line up in the center of the cell, and get pulled apart.
- Membranes form around each of the sets of chromosomes. These become Nuclei of the two cells.
- The cytoplasm divides
- You have two new identical cells carrying the same DNA
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Meiosis is a sexual cell reproduction
During sexual reproduction, two cells called gametes combine to form a new individual.
- Gametes only have one copy of each chromosome.
- This is because you have a cell from the mother and a cell from the father and still have the same number of chromosomes, for example the human body cells have 46 chromosomes.
- The new individual will have a mixture of two sets of chromosomes, so it will inherit features from the mother and the farther.
Process of meiosis:
- Before the cell starts to divide, it duplicates its DNA. one arm of each chromosome is an exact copy of the other arm.
- In the frst devision in meiosis, the chromosome pairs line up in the center of the cell.
- The pairs are then pulled apart, so each new cell only has one copy of each chromosome.
- In the second division the chromosomes line up again in the center of the cell.like mitosis the arms are pulled apart.
- You get four gametes each with only a single set of chromosomes in it.
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- Differentiation is the process by which a cell changes to become specialised for its job.
- Some cells are undifferentiated. They can develop into different types of cell depending on what instructions they're given. These cells are called stem cells.
- Stem cells are found in early human embryos, they have the potential to turn into any kind of cell.
- Medicine already uses adult stem cells to cure diseases.
- Scientists can also extract stem cells from very earl human embryos and grow them.
- Some people are against stem cell research because they feel that human embryos shouldn't be used for experiments since each one is a potential human being.
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