Genetics Misconceptions

Genetics Misconceptions

Common Genetics Misconceptions

• Only certain people have disease genes.

  • False. The term "disease gene" is inaccurate; it should refer to specific alleles associated with disorders.

  • Everyone carries two alleles for each gene, including those associated with genetic disorders.

  • The likelihood of carrying a disease-causing allele is generally rare.

• Different body cells of the same person have different DNA sequences, which is why the cells are different.

  • False. With few exceptions (e.g., immune cells), all cells in a person's body have the same DNA sequence, derived from the original zygote through mitosis.

  • Cellular differences arise from transcriptional regulatory proteins and gene regulatory switches, leading to differential gene transcription and protein production in different cell types.

• Dominant traits are the most common traits in the population.

  • False. Dominance relates to the phenotype of a heterozygote (an individual with two different alleles).

  • Dominance varies depending on the gene, alleles, and phenotype in question.

  • Most traits exhibit significant variation in a population and are influenced by multiple genes (polygenic), unlike the single-gene traits studied by Gregor Mendel.

  • Predicting dominance requires controlled breeding; population traits show a mix of dominant, recessive, and neither.

• Only one of the two alleles or versions of a gene that a person has is expressed.

  • False. Both alleles in a diploid cell are typically expressed, meaning they are transcribed into mRNA and translated into protein.

  • Exceptions include certain mutations (e.g., deletions) or specific cellular conditions where only one allele is expressed.

• Genes make proteins.

  • False. Genes, which are DNA sequences in chromosomes, are information. They don't actively

Common Genetics Misconceptions

• Only certain people have disease genes.

  • False. The term "disease gene" is inaccurate; it should refer to specific alleles associated with disorders.

  • Everyone carries two alleles for each gene, including those associated with genetic disorders.

  • The likelihood of carrying a disease-causing allele is generally rare. Most people are carriers, meaning they have one normal allele and one disease-causing allele, and typically do not exhibit symptoms of the disorder.

• Different body cells of the same person have different DNA sequences, which is why the cells are different.

  • False. With few exceptions (e.g., immune cells undergoing somatic recombination), all cells in a person's body have the same DNA sequence, derived from the original zygote through mitosis. This ensures genetic consistency across all cells.

  • Cellular differences arise from transcriptional regulatory proteins and gene regulatory switches, leading to differential gene transcription and protein production in different cell types. These regulatory mechanisms determine which genes are active in each cell, dictating the cell's specific function and characteristics.

• Dominant traits are the most common traits in the population.

  • False. Dominance relates to the phenotype of a heterozygote (an individual with two different alleles).

  • Dominance varies depending on the gene, alleles, and phenotype in question. A dominant allele only needs to be present on one chromosome to be expressed, whereas a recessive allele must be present on both chromosomes.

  • Most traits exhibit significant variation in a population and are influenced by multiple genes (polygenic), unlike the single-gene traits studied by Gregor Mendel. Polygenic traits include height, skin color, and metabolic rate.

  • Predicting dominance requires controlled breeding; population traits show a mix of dominant, recessive, and neither. Observed frequencies of traits in a population are influenced by evolutionary pressures, mutation rates, and genetic drift.

• Only one of the two alleles or versions of a gene that a person has is expressed.

  • False. Both alleles in a diploid cell are typically expressed, meaning they are transcribed into mRNA and translated into protein. This is known as co-dominance or incomplete dominance, where both alleles contribute to the phenotype.

  • Exceptions include certain mutations (e.g., deletions) or specific cellular conditions where only one allele is expressed. Genomic imprinting and X-inactivation are examples of such exceptions, where gene expression depends on the parent of origin or the number of X chromosomes.

• Genes make proteins.

  • False. Genes, which are DNA sequences in chromosomes, are information. They don't actively make anything but rather provide instructions for protein synthesis. The process involves transcription (DNA to mRNA) and translation (mRNA to protein), facilitated by various enzymes and cellular structures such as ribosomes.