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Explain the concept of dominance and give an example.
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Dominance refers to an allele that masks the effect of a recessive allele. Example: T (tall) is dominant over t (short). TT or Tt results in tall phenotype.
What is the hierarchical organization of the body starting from cells?
Cells → Tissues → Organs → Systems
What are the three main components of DNA?
Sugar backbone (deoxyribose), phosphate, nitrogenous bases
What are the possible genotypes for a person with blood type A?
AA or AO
What does it mean for an individual to be homozygous for a trait?
An individual with two identical alleles for a trait, e.g., TT or tt.
What does it mean when alleles IA and IB show co-dominance?
IA and IB alleles both express their traits when present together, resulting in blood type AB (both antigens present).
What is the genotype-phenotype relationship in blood type O?
Genotype OO results in blood type O, which means no antigens are present on the red blood cells.
Define locus in the context of genetics.
Locus is the specific location of a gene on a chromosome.
Give an example of how co-dominance works in human blood types.
In blood type AB, both IA and IB alleles are expressed equally, resulting in the presence of both A and B antigens on red blood cells.
What is expressivity, and how does it contribute to genetic variability?
Expressivity is the degree to which a genotype is expressed in an individual, contributing to varying degrees of trait manifestation, such as in neurofibromatosis.
How does penetrance affect the manifestation of a genotype?
Penetrance measures the proportion of individuals with a genotype that displays the expected phenotype. For example, 50% penetrance means only 50% of individuals show the trait.
What is the difference between a gene and an allele?
A gene is a segment of DNA on a chromosome; an allele is a form of a gene, with one allele inherited from each parent.
Explain the difference between genotype and phenotype.
Genotype refers to the genetic makeup of an individual (the alleles they possess), while phenotype is the observable physical traits resulting from the genotype.
How many chromosomes do humans have in their somatic cells?
46 chromosomes
What does it mean for an individual to be heterozygous for a trait?
An individual with two different alleles for a trait, e.g., Tt.
What transformation processes take place from DNA to enzyme synthesis?
Replication (DNA copying), Transcription (DNA to RNA), Translation (RNA to proteins)
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