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Genetics - Coggle Diagram
Genetics
Mitosis
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Mitosis creates 2 identical daughter cells form each parent cell. Each of these cells maintain a full set of identical chromosome ( diploid)
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Meiosis
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Meiosis divides one parent cell into 4 gamete cells. Each gametes has half the number of chromosomes of the patterns cell ( haploid ). Male and a female gamete recombine during fertilization to form a cell with the complete set of chromosomes.
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Meiosis
During meiosis there are three opportunities for increased variation firstly when the homologous pairs line up.
It's different each time meiosis occurs as one chromosome from each pair will go to each new gameete
( called independent assortment) and each contain a different collection of alleles ( although they both have t
he same genes ) .
Secondly portions from each homologous pair swap ( called crossing over ) creating different combinations of alleles in once identical copies .
Thirdly one half of each doubled chromosome is pulled apart and combined with one of other chromosomes.
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Haploid and diploid
Gametes contain only one set of chromosomes known as haploid ( or half ) . All other cells in an organism contain the usual two sets of chromosomes inherited from both parents and are known as diploid ( 2 or double ).
Test Crosses
The test cross is used to determine the phenotype of an unknown individual that displays the dominant phenotype.
The individual is crossed with a known homozygous recessive.
When you do a test cross , if you produce any offspring with a recessive trait , the individual is heterozygous.
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Phenotype and genotype
The genotype is the combination of alleles that an organism contains. For any particular trait they can be heterozygous (different : Tt ) or homozygous (same : recessive is tt and dominant is TT). The phenotype is the physical trait that occurs because of the alleles.
When the phenotype is recessive then the genotype can only be homozygous recessive as well. If the phenotype is dominant then the genotype can either be heterozygous or homozygous dominant, as long a one dominant allele is present in the genotype
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