Chapter 12.2: Monohybrid Crosses: The Principle of Segregation Flashcards
What is a monohybrid cross?
• A monohybrid cross is a cross that follows only two variations on a single trait
Define first filial (F1) generation
the offspring resulting from a cross between a parental generation (P); in experimental crosses, these parents usually have different phenotypes
What is the offspring resulting from a cross between a parental generation (P); in experimental crosses, these parents usually have different phenotypes?
first filial (F1) generation
Define dominant allele
an allele that is expressed when present in either the heterozygous or the homozygous condition?
What is an allele that is expressed when present in either the heterozygous or the homozygous condition?
dominant allele
Define recessive allele
an allele that is only expressed when present in the homozygous condition, but being “hidden” by the expression of a dominant allele in the heterozygous condition
What is an allele that is only expressed when present in the homozygous condition, but being “hidden” by the expression of a dominant allele in the heterozygous condition?
recessive allele
Define Mendelian Ratio
the characteristic dominant-to-recessive phenotypic ratios that Mendel observed in his genetic experiments
What is the characteristic dominant-to-recessive phenotypic ratios that Mendel observed in his genetic experiments?
Mendelian Ratio
Define allele
one of two or more alternative states of a gene
What is one of two or more alternative states of a gene?
allele
Define homozygous
having two identical alleles of the same gene
What is having two identical alleles of the same gene?
homozygous
Define heterozygous
having two different alleles of the same gene
What is having two different alleles of the same gene?
heterozygous
Define genotype
the genetic constitution underlying a single trait or set of traits
What is the genetic constitution underlying a single trait or set of traits?
genotype
Define phenotype
the realized expression of the genotype; the physical appearance or functional expression of a trait
What is the realized expression of the genotype; the physical appearance or functional expression of a trait?
phenotype
What does the Principle of Segregation state?
The two alleles for a gene segregate during gamete formation and are rejoined at random, one from each parent during fertilization
Define punnet square
a diagrammatic way of showing the possible genotypes and phenotypes of genetic crosses
What is a diagrammatic way of showing the possible genotypes and phenotypes of genetic crosses?
punnet square
Define pedigree
a consistent graphic representation of matings and offspring over multiple generations for a particular genetic trait
What is a consistent graphic representation of matings and offspring over multiple generations for a particular genetic trait?
pedigree
Is albinism a dominant or recessive trait?
recessive
Is Alkaptonuria a dominant or recessive trait?
recessive
Is Duchenne Muscular Dystrophy a dominant or recessive trait?
recessive
Is Hemophilia a dominant or recessive trait?
recessive
Is Sickle Cell Anemia a dominant or recessive trait?
recessive
Is Middigital Hair a dominant or recessive trait?
dominant
Is Brachydactyly a dominant or recessive trait?
dominant
Is Huntington Disease a dominant or recessive trait?
dominant
Is Phenylthiocarbamide (PTC) sensitivity a dominant or recessive trait?
dominant
Is Camptodactyly a dominant or recessive trait?
dominant
Is Hypercholesterolemia a dominant or recessive trait?
dominant
Is Polydactyly a dominant or recessive trait?
dominant
Is Red-green color blindness a dominant or recessive trait?
recessive
What is the phenotype for albinism?
Lack of melanin pigmentation
What is the phenotype for Middigital Hair?
Presence of hair on middle segment of fingers
What is the phenotype for Alkaptonuria?
Inability to metabolize homogentisic acid
What is the phenotype for Brachydactyly?
Short fingers
What is the phenotype for Red-green color blindness?
Inability to distinguish red or green wavelengths of light
What is the phenotype for Huntington Disease?
Degeneration of nervous system, starting in middle age
What is the phenotype for Cystic Fibrosis?
Abnormal gland secretion, leading to liver degeneration and lung failure
What is the phenotype for Phenylthiocarbamide (PTC) sensitivity?
Ability to taste PTC as bitter
What is the phenotype for Duchenne Muscular Dystrophy?
Wasting away of muscles during childhood
What is the phenotype for Camptodactyly?
Inability to straighten the little finger
What is the phenotype for Hemophilia?
Inability of blood to clot properly, some clots form but the process is delayed
What is the phenotype for Hypercholesterolemia ?
Elevated levels of blood cholesterol and risk of heart attack
What is the phenotype for Sickle Cell Anemia?
Defective hemoglobin that causes red blood cells to curve and stick together
What is the phenotype for Polydactyly?
Extra fingers and toes
