18 Questions
Which blood type demonstrates incomplete dominance in human genetics?
Blood type AB
What type of dominance is exhibited when heterozygotes show a mixture of phenotypic characters of both homozygotes?
Incomplete dominance
What do lethal genes cause in an organism?
End of life
How many alleles are involved in determining human blood type?
3
What term refers to traits controlled by two or more genes?
Polygenic traits
Which genetic concept involves the interaction of more than one gene to determine a trait?
Polygenic inheritance
What term refers to the physical expression of a trait?
Phenotype
Which of the following accurately describes a homozygous organism?
It has the same two copies of a gene for a particular trait.
What happens if an organism is heterozygous for a particular trait?
It carries two different copies of a gene for that trait.
In Mendel's Law of Inheritance, what is the Punnett square used for?
Predicting the genotypical outcome probabilities of offspring.
Which genetic material refers to the set of genes in our DNA responsible for a particular trait?
Genotype
Which term describes an individual that has one dominant and one recessive allele for a trait?
Heterozygous
What is the key difference between a monohybrid cross and a dihybrid cross?
Number of traits being crossed
What does the Law of Segregation state?
Each pair of alleles segregates during meiosis
In Mendel's experiments, what does it mean when he crossed parents with 'pure, contrasting traits'?
Both parents were homozygous recessive
Which allele is considered dominant?
Trait-controlling allele
What happens during the Law of Independent Assortment?
Alleles for different genes segregate independently
How do homozygous organisms differ from heterozygous organisms?
Heterozygous organisms have two identical alleles
Study Notes
Genetic Terms
- An individual inherits two alleles for each gene, one from each parent.
- Genotype: the set of genes in our DNA responsible for a particular trait.
- Phenotype: the physical expression, or characteristics, of that trait.
- Examples: PP and pp are alleles of the pea plant flower color, with PP representing purple flowers and pp representing white flowers.
Genetic Traits
- Homozygous: an organism with the same two copies of a gene for a particular trait.
- Heterozygous: an organism with different copies of a gene for a particular trait.
- Examples: TT/TT and TT/tt are genotypes, with TT/TT being homozygous and TT/tt being heterozygous.
Dominant and Recessive Traits
- Dominant: the allele that is expressed and overrules the recessive gene, denoted by capital letters.
- Recessive: the allele that is expressed only if both connected alleles are recessive, denoted by lower case letters.
- Examples: dominant traits include dark hair, curly hair, and freckles, while recessive traits include blonde or red hair, straight hair, and blue eyes.
Mendel's Law of Inheritance
- Punnett Square: a tabular summary of possible combinations of maternal alleles with paternal alleles.
- Law of Segregation: each pair of alleles segregates, or separates, during meiosis.
- Law of Dominance: when parents with pure, contrasting traits are crossed together, only one form of trait appears in the next generation.
- Law of Independent Assortment: the alleles of two (or more) different genes get sorted into gametes independently of one another.
Non-Mendelian Patterns of Inheritance
- Incomplete Dominance: a mixture of the alleles in the genotype is seen in the phenotype, such as pink flowers of 4'o clock plant.
- Lethal Genes: alleles causing the end of an entity which carries it, such as Huntington's disease.
- Sex-Linked Inheritance: transmission of traits or characters from parents to offspring through sex chromosomes, such as X-linked hemophilia and Y-linked Hypertrichosis.
- Multiple Alleles: an excellent example is human blood type, with four possible phenotypes: A, B, AB, and O.
- Polygenic Traits: traits controlled by two or more genes.
- Monohybrid vs Dihybrid Cross: a monohybrid cross involves parents differing in one trait, while a dihybrid cross involves parents differing in two traits.
Additional Concepts
- Codominance: two dominant alleles are present and combined.
- Tetrahybrid Cross: a breeding experiment between two organisms that are identical hybrids for four traits.
Test your knowledge on genetics concepts like incomplete dominance and lethal genes. Learn about how traits associated with each allele are displayed simultaneously and how lethal genes can lead to the end of an entity. Perfect for students studying genetics or biology!
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