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MITOSIS, MEIOSIS AND BINARY FISSION
Terms in this set (34)
Nuclear division in somatic cells.
Produces 2 diploid daughter cells which are exact clones of parent cell.
the phase in which a cell grows, performs its normal functions, replicates the DNA, and prepares for mitosis.
The first stage of mitosis. The chromatin condenses into chromosomes and the nuclear envelope dissolves
The chromosomes line up across the middle of the cell.
The chromosome pairs seperate and move to opposite poles of the cell.
A new nuclear envelope forms around each set of chromosomes at opposite poles of the cell.
The final stage of the cell cycle that takes place immediately after mitosis. The cell's cytoplasm divides, distributing the organelles into each of the two daughter cells before they seperate completely
Semi - permeable membrane surrounding the nucleus.
Microtubule structure that seperates chromosomes during mitosis.
Structure that helps to form spindle fibres.
One of the two strands that make up a chromosome.
Coils of DNA that condense to form chromosomes.
Distinct worm-like, linear structure formed from chromatin during cell cell reproduction.
A reduction division that produces gametes for sexual reproduction. Produces 4 genetically unique daughter cells.
MEIOSIS STAGE 1
Chromosome pairs seperate
Chromosomes begin to condense
- Homologous chromosomes pair
- Crossing over occurs
- Spindle fibres attach to cell
- Chromosomes line up across the middle of the cell.
Chromosomes start to move to opposite poles of the cell as spindle fibres begin to shorten
Chromosomes reach opposite ends of the cell
Cellular membrane forms
Final division for 2 cells to be formed, the two new daughter cells are both haploid.
MEIOSIS STAGE 2
- nuclear membrane dissolves
- Spindle fibres form
(Same as metaphase I) Spindle fibres attach to cell and chromosomes line up across the middle of the cell.
Chromosomes divide and sister chromatids move to opposite ends of the cell as spindle fibres shorten.
(same as telophase I) Chromosomes reach opposite ends of the cell and cellular membrane forms.
Chromosomes divide into 4 gametes that each have single chromosomes and a new mix of genetic material.
WHY IS MEIOSIS IMPORTANT?
The long term surivival of a species depends on its ability to adapt to a constantly changing environment. Therefore, the offspring nned to be different from their parents, as well as each other. Meiosis gives variation to a population and this gives species the potential to evolve.
WHY IS MITOSIS IMPORTANT?
Produces daughter cells which are exact copies of the parent cell.
- Asexual reproduction.
Specialised cell involved in sexual reproduction
process by which homologous chromosomes exchange pieces, resulting in greater genetic variety
VARIETY IS BROUGHT ABOUT BY
-The production and fusion of haploid gametes (mixing of the genotypes)
-The creation of genetic variety by crossing over between homologous chromosomes during prophase I.
Division of a cell into two without mitosis. A prokaryotic cell splits to form two daughter cells.
HOW DOES BINARY FISSION HAPPEN?
-A single DNA molecule attached to the plasma membrane at a specific point.
-DNA molecule replicates
-2 copies seperate by expansion of the plasma membrane
-The plasma membrane and cell wall dent inwards to divide the cytoplasm resulting in 2 daughter cells
DIFFERENCESB/W MITOSIS AND MEIOSIS
Single division of the nucleus
Number of chromosomes remain the same Crossing over never occurs
2 daughter cells formed
Daughter cells are identical to parent cells MEIOSIS
Double division of the nucleus
Number of chromosomes is halved (reduction division)
Crossing over may occur
4 Daughter cells formed
Daughter cells are genetically different from the parent cells.