A segment of DNA on a chromosome that codes for a specific trait
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allele
Different forms of a gene
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Dominant allele
one whose trait always shows up in the organism when the allele is present
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Recessive allele
An allele that is hidden whenever the dominant allele is present
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Punnett square
A chart that shows all the possible combinations of alleles that can result from a genetic cross
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Phenotype
An organism's physical appearance, or visible traits.
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Genotype
genetic makeup of an organism
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homozygous
An organism that has two identical alleles for a trait
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Heterozygous
having two different alleles for a trait
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incomplete dominance
occurs when one allele is only partially dominant
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codominance
occurs when both alleles for a gene are expressed equally
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meiosis
the process by which the number of chromosomes is reduced by half to form sex cells
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polygenic inheritance
occurs when more than one gene affects a trait
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what does polygenic inheritance result in?
A broad range of phenotypes
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What is an example of codominance?
AB blood type
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What is an example of incomplete dominance?
red flower + white flower \= pink flower
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What is the percentage of heterozygous genotypes if Both parents are heterozygous? (Use Punnett Square)
50%
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What is the difference between incomplete dominance and codominance?
In codominance, both alleles in the genotype are seen in the phenotype. In incomplete dominance, a mixture of the alleles in the genotype is seen in the phenotype.
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Why would a pea plant be tall when it's a hybrid for stem height?
Hybrid pea plant is stem height tall because it has one dominant and one recessive allele. In a situation like this, the dominant allele covers up the recessive allele for short stems.
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what happens during meiosis
During meiosis, the chromosome pairs separate into two different cells. The sex cells that form later have only half as many chromosomes as the other cells in the organism.
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