Unit A Section 3.2 Flashcards
When a unicellular paramecium splits…….
When a unicellular paramecium splits to form two new organisms during binary fission, its cell contents are divided equally between the two new cells.
What happens if its DNA molecule were divided between the two organisms?
When each new individual would have only half the DNA of the parent cell, and half the genetic information it would need to function.
How do you avoid this?
- the parent cell first makes an exact copy of its DNA, and each chromosome doubles.
- For a short time, the parent cell has twice the amount of DNA it usually has. When the cell eventually divides, each new cell gets one complete copy of the DNA.
What is mitosis?
- In multicellular organisms, it is the process that produces two new cells with the same number of chromosomes
- Mitosis occurs in the body cells of multicellular organisms
- is responsible for the growth and cellular repair of a multicellular organism.
What if the sex cells contained the same amount of DNA as every other cell?
then the zygote would receive twice the amount of DNA it needs.
What is Meiosis?
Meiosis is a type of cell division that produces cells with only half the DNA of a normal cell.
Because each gamete has only half the DNA of a normal cell, when the male and female gametes unite, the zygote has a complete set of DNA.
What does Meiosis process involve?
- Meiosis involves two cell divisions, not just one.
- Each chromosome in the pair contains the same set of genes but may contain different alleles (forms) of those genes. A gamete must contain only one copy of each different chromosome.
- To do this, cells must divide twice
What is the difference between meiosis and mitosis?
- Mitosis produces two offspring cells with the same number of chromosomes as the parent cell.
- Meiosis produces four sex cells that have half the number of chromosomes as the parent cell.
How many times can human body cells divide?
human body cells can divide only about 50 times in the laboratory before they die.
