BIO 327 Study Guide - Quiz Guide: Semiconservative Replication, Epistasis, Frederick Griffith
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Exam #5: genetics review: phenotype: physical trait. Genotype: the combination of the information of the two alleles. Homozygous: both genes in genotype are the same. Allele: different forms of a gene that occupy the same loci homologous chromosome. Genes is a stretch of a dna sequence that determines a particular trait. Genes mutate and take two or more forms, called alleles. Locus: alleles are variants of the same genes that occur on the same place on a chromos. Pure bred peap plants always have offspring with the same genotype. Therefore, when two homozygous plants with differing genotypes are mated/crossed, if only one trait is expressed it is known as the dominant trait: the separation of homologous chromosomes during meiosis is known as disjunction or. __________ of alleles: a tall pea plant is crossed with a short pea plant. Fifty percent of the offspring are short and fifty percent are tall.
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These all relate to exceptions to the inheritance patterns encountered by Mendel.â
Why do multiple and lethal alleles often result in modifications of the classic Mendelian monohybrid and dihybrid ratios?
Select the four correct statements.
-When an essential gene is mutated, it can result in a lethal phenotype. There are no classic Mendelian monohybrid and dihybrid ratios. |
-In the case of codominance, heterozygotes produce gene products from both alleles of a gene. Classic Mendelian monohybrid and dihybrid ratios are modified by codominance. |
-In the case of incomplete dominance, the phenotype of the heterozygote is distinct from and often intermediate to the phenotypes of homozygous individuals. Classic Mendelian monohybrid and dihybrid ratios are modified by incomplete dominance. |
-Genes exist in a large number of allelic versions and a diploid organism has two homologous gene loci that may be occupied by different alleles of the same gene. This can result in many different phenotypes for traits, which may not follow typical Mendelian ratios. |
-When an essential gene is mutated, it can result in a lethal phenotype. This results in a modification of classic Mendelian ratios. |
-The phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous genotypes. The joint expression of both alleles in a heterozygote is called codominance. There are no classic Mendelian monohybrid and dihybrid ratios. |
-Genes exist in a large number of allelic versions, but in a diploid organism, only one allele of the gene can occupy one homologous gene loci. Classic Mendelian inheritance cannot explain this phenomenon. |
-Each gene produces a unique gene product. The effect of one allele in a heterozygote completely masks the effect of the other. Classic Mendelian genetics cannot explain this phenomenon. |