Topic Seven - Genotypes and Phenotypes Flashcards
What is a genotype?
A genotype is the underlying genetic make-up of an organism that determines its characteristics or phenotypes. It consists of the specific alleles of a gene or genes that are present and active.
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What are autosomal genes?
Autosomal genes are genes located on autosomes, present in both males and females. Each individual has two alleles for an autosomal gene, one on each chromosome.
Hemizygous genotypes can only occur…
in males for x-linked and y-linked genes.
What is complete dominance?
Complete dominance occurs when the dominant allele fully masks the effect of the recessive allele in a heterozygous condition. The heterozygote’s phenotype is the same as that of the homozygous dominant genotype.
What is a phenotype?
A phenotype is the observable or measurable characteristics of an organism, resulting from the interaction between its genotype and the environment.
What is a carrier?
A carrier is a heterozygote that possesses the allele for a recessive trait but doesn’t display the trait in their phenotype. Carriers can have hidden recessive traits that don’t affect normal functioning or may carry alleles for recessive disorders.
What is codominance?
Codominance occurs when a heterozygote expresses both the dominant and recessive traits of a gene in its phenotype. It’s a form of partial dominance, and both alleles contribute to the phenotype. An example is the multiple alleles controlling flower color in rhododendron plants.
What is incomplete dominance?
Incomplete dominance is a gene interaction where both alleles are partially expressed, resulting in an intermediate phenotype. For example, in humans, it’s seen in hair type. In plants, it can be observed in snapdragons’ flower colors.
What are the differences between complete dominance, incomplete dominance, and codominance?
Complete dominance shows the dominance of one allele over the other, codominance involves both alleles expressing themselves, and incomplete dominance results in an intermediate or blending phenotype between parental traits.
What is the relationship between phenotype and alleles?
Phenotype is the observable characteristic determined by the interaction of an organism’s genotype and the environment. Different dominance patterns dictate how alleles are expressed in the phenotype.
How does the phenotype of an organism result from genotype and environment interaction?
Phenotype can be influenced by both genotype and environment. Some traits are a result of the interaction between the genetic makeup (genotype) and external factors (environment).
What is epigenetics?
(above genetics) Epigenetics is the study of how cells with identical genotypes can exhibit different phenotypes. It explores changes in gene expression that occur without altering the underlying DNA sequence.
What are epigenetic factors?
Epigenetic factors are external agents that act on DNA, switching genes permanently ‘on’ or ‘off.’ They modify DNA packaging and labeling, affecting gene expression without changing the DNA sequence itself.
How does epigenetic factors influence gene expression?
Epigenetic factors can affect gene expression by altering DNA packaging. Tightly packaged DNA segments are silenced, while open packaging allows genes to be active and produce proteins.
What is DNA labeling through epigenetic modifications?
DNA can be labeled with epigenetic tags, such as methyl groups. Methylation, the addition of methyl groups to specific bases in DNA, can change gene expression and permanently affect gene activity
