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Law of Independent Assortment
Explains how traits are inherited independently.
Father of Genetics
Gregor Mendel is known as the 'Father of Genetics'.
Dominant allele
Expressed when only one copy is present.
Fundamental unit of heredity
Gene is the fundamental unit of heredity.
Codominance
In codominance, the heterozygous phenotype shows both traits equally.
Alternative forms of a gene
Alleles are alternative forms of a gene.
Incomplete dominance
A red flower crossed with a white flower produces pink flowers.
Observable traits
The observable traits of an organism are referred to as its phenotype.
X chromosome
Carries most sex-linked traits.
Homozygous
If an organism has two identical alleles for a trait, it is homozygous.
X-linked recessive traits
Males are more likely to express X-linked recessive traits because they have only one X chromosome.
Law of Segregation
States that alleles separate during gamete formation.
Punnett square
Used to predict genetic outcomes.
Monohybrid cross
Examines one trait.
Expected phenotypic ratio for a heterozygous monohybrid cross
Is 3:1.
Dihybrid cross
Involves two genes.
Expected phenotypic ratio for a heterozygous dihybrid cross
Is 9:3:3:1.
Main source of genetic variation
Is mutation.
Gene recombination
Occurs during meiosis.
Down syndrome
Is caused by chromosomal abnormalities.
Gene flow
Refers to genetic exchange between populations.
Environmental factor affecting phenotype
Temperature is an environmental factor affecting phenotype.
Genetic counseling
Is based on Mendelian principles.
Chromosomal variation involving loss of a segment
Is deletion.
Chromosomal variation resulting in an extra copy
Is duplication.
Chromosomal variation involving rearrangement
Is translocation.
Down syndrome
A genetic disorder caused by the presence of an extra chromosome 21.
Crossing over
A process that results in a new combination of alleles during meiosis.
Mendel's work
Laid the foundation for modern genetics.
Homozygous
An organism with two identical alleles for a trait.
Phenotype
The observable characteristics of an organism.
Alleles
Different versions of a gene.
Incomplete dominance
A genetic situation in which one allele does not completely dominate another allele, resulting in a new phenotype.
Codominance
A genetic scenario where both alleles are equally expressed in the phenotype.
Genotypic ratio of F2 generation in incomplete dominance
1:2:1.
Expected phenotypic ratio when crossing two pink snapdragon flowers (Rr)
1 red : 2 pink : 1 white.
Probability of getting a red-flowered offspring
50% when a heterozygous pink flower is crossed with a red flower.
Percentage of offspring that will be pink when two heterozygous pink flowers (Rr) are crossed
50%.
Example of incomplete dominance
Red and white snapdragon flowers producing pink offspring.
Phenotype of an Rr individual in snapdragons
Pink.
Mendelian principles
Basic rules of inheritance established by Gregor Mendel.
Trisomy 21
Another term for Down syndrome, characterized by the presence of an extra 21st chromosome.
Law of Independent Assortment
Mendel's principle that states alleles for different traits are distributed to sex cells (& gametes) independently of one another.
Temperature's effect on genetic expression
Can influence the phenotype of certain traits.
Blood type AB
An example of codominance in humans where both A and B alleles are expressed.
Intermediate phenotype in incomplete dominance
The heterozygous phenotype is a blend of the dominant and recessive phenotypes.
Genetic exchange between populations
Occurs when alleles are shared between different groups, contributing to genetic diversity.
Mutation
A change in the DNA sequence that can lead to different traits.
X-linked inheritance
Traits that are determined by genes located on the X chromosome.
F1 generation
The first filial generation, which is the result of a cross between two parental organisms.
Expected offspring from a pink and white flower cross
50% pink and 50% white.
Alleles separate during gamete formation
A principle of Mendel's law of segregation.
Complete dominance
One allele is completely dominant over the other.
Incomplete dominance
The heterozygous phenotype is an intermediate of both alleles.
Codominance
Both alleles are expressed equally in the heterozygote.
Recessive allele
The recessive allele is not expressed.
Eye color
An example of a trait influenced by multiple alleles.
Blood type AB
A blood type resulting from the genotype IAIB.
Skin color
An example of a polygenic trait influenced by multiple genes.
Hair type
An example of a trait that can show multiple phenotypes.
Genotype for blood type AB
IAIB.
Genotype for type O blood
ii.
Phenotypic ratio of offspring from heterozygous codominant individuals
1:2:1.
Possible blood types of offspring from IAIA and IBi parents
A, B, and AB.
Probability of type O child from IAi and IBi parents
25%.
Blood type A
Has only A antigens.
Blood type B
Has only B antigens.
Blood type AB
Has both A and B antigens.
Inheritance pattern of red and white spotted petals
Codominance.
Third phenotype distinct from both parents
Polygenic inheritance.
Blood type AB donation
Can donate to any blood type.
Statement about incomplete dominance and codominance
Incomplete dominance shows a blended trait, codominance shows both traits distinctly.
Outcome of codominance in flower color
The flower would have both red and white patches.
Parents' blood types for a child with blood type AB
Cannot be AB and O.
Percentage of white offspring from roan cattle
25%.
Heterozygous genotype in codominance
Both alleles being equally expressed.
Phenotype
The observable characteristics of an organism resulting from the interaction of its genotype with the environment.
Heterozygous phenotype
An intermediate of the two alleles.
Blood type AB
A blood type characterized by the presence of both A and B antigens.
IAIB
The genotype for blood type AB.
Lethal allele
An allele that causes death when homozygous.
Dominant lethal allele
An allele that is always dominant and can cause death before reproductive age.
Recessive lethal allele
An allele that is only lethal in homozygous individuals.
Multiple alleles
A gene that has more than two allelic forms.
Universal recipient
A person with blood type AB who can receive blood from any type.
Survival ratio for recessive lethal allele
Typically 2:1 when heterozygous carriers are crossed.
Sickle-cell anemia
An example of a disease caused by a lethal allele.
Huntington's disease
An example of a dominant lethal allele.
Polydactyly
An example of a lethal allele.
Pedigree chart
A diagram used to show the genetic relationships among a group of individuals.
Type O blood
A blood type characterized by the absence of A and B antigens.
Genotype for blood type O
ii.
Possible genotypes for type B blood
IBIB and IBi.
Possible blood types of parents for a child with blood type AB
A and B.
Expected survival ratio for a cross between two heterozygous carriers of a recessive lethal allele
2:1.
Flower phenotype in codominance
The flower would have both red and white patches.
Blood type characteristics
Type A and B can be present in the same individual.
Example of a trait controlled by multiple alleles
Blood type.
Inheritance of lethal alleles
They are passed down through dominant inheritance.
Probability of inheriting a lethal allele from a heterozygous parent
25%.
